NOVEMBER 2020
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MOTION SYSTEM APPLICATIONS
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Spotlight on motion system applications IT’S
here – our annual Motion System Applications special issue. Each year our editorial team here at Design World puts together four special issues on motion control, with the last one of the year focusing on the many and varied applications for motion systems.
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This special issue highlights some top application examples and how many of the vast array of motion control components, separate or together, are used to tackle some of the most challenging applications. These span a range of industries across manufacturing including medical devices, but also in packaging and material handling as well as the booming robotics field. In fact, it’s clear that one of the most common applications driving the development and evolution of many motion components is robotics. The reverse is true too, of course – as controllers have shrunken in size they’ve packed more processing power, and the motors and actuators that robots rely on continue to pack more power in smaller frames. Case in point; a soft robotic glove that aids in strengthening the gripping force of human workers. The micro motors used in the glove capitalize on the trend in motor design for powerful rare-earth magnetic materials that increase power density and decrease size. Such small, powerful motors are also common in many medical devices. Included in this issue is a short guide to selecting the right motor for medical device applications – specifically, choosing between brushless dc motors and brushed dc motors in reusable and disposable medical tools. Besides motors, motion controllers and networking combined are tackling some big projects. For instance, the giant Magellan telescope in the Chilean Andes. The rotation and movements of the telescope’s mirrors and the giant enclosure housing the telescope are controlled by motion controllers. Together with an FSoE (Fail Safe over EtherCAT) safety network link, they also control the telescope’s interlock and safety system. This special issue also highlights linear technology of various kinds, including linear electric actuators used in a shampoo bottle filling line that replaced older pneumatic actuators, which tended to cause some spills that required additional clean up operations. As always, we hope you find what we’ve assembled in this special issue on motion system applications useful. Do you have any interesting challenges that you or your company overcame? Want to share it with our readers? Get in touch with me via email at mbudimir@wtwhmedia.com or on Twitter at @DW_Motion. And don’t forget that you can find all of the latest motion control news at our motionspecific sites motioncontroltips.com and linearmotiontips.com, as well as bearingtips.com and couplingtips.com.
MILES BUDIMIR • SENIOR EDITOR
(408) 460-1345
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11 • 2020
THINK INSIDE THE BOX Exceptional designs deserve superior components. The developer of the original world-class linear motion systems, THK continues to redeďŹ ne industry standards and to meet an ever-growing range of needs. From aerospace and machine tool to packaging and medical, THK products play a vital role in the advancement of technology and capability.
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2014 Winner
2014 - 2016
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VO LU M E 6 N U M B E R 4
CONTENTS 2 6 12 16 18 22 26 29 32 35 42 46 51 56 58 62 64
Editorial Linear actuators & guides Brakes & clutches Bearings Cables & connectivity Motion controls & drives Conveyors Couplings Encoders Gears & gearsets Motors Brushless & brush dc motors & drives Stages • Gantries • Hexapod platforms Sensors Shocks • Damping • Gas springs Retaining rings Ad index
O N T H E C OV E R Mikron machines (which make up to 100 face masks a minute) use an array of components from Festo — including CMMT servo drives and EMMT electric motors, DFM guided drives, ADN pneumatic cylinders, MPA and MS6-SV-E valves, and DSNU round cylinders … all components in stock worldwide and available within 24 hours. Such availability is key in systems for addressing COVID-19. The Mikron machines can be transported (and operated in) standard shipping containers. motioncontroltips.com | designworldonline.com
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Festo CMMT-ST/AS servo drives used in the mask-making machine are compatible with higher-level controllers from Beckhoff, Siemens, and Rockwell … and Festo Automation Suite software speeds integration and commissioning.
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MOTION SYSTEM APPLICATIONS
Applications for Electric actuators
ELECTRIC
actuators come in versions as small as syringes for medical applications to those big enough to drive industrial presses. These muscles of precision motion usually incorporate an electric motor and rotary-to-linear device for conversion of torque to linear force. No matter the application, electric actuators deliver repeatability that’s indispensable for moving loads to a given positions. Often they’re also more controllable than fluid-power actuators,
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giving engineers a way to shape speed, force and acceleration of machine-axis moves. Another benefit for applications that need multiple outputs over time is that most electric actuators are programmable so adapt to changing conditions. Applications with similar dynamics often make use of the same actuator types — those that pair motors with ballscrews or leadscrews; incorporate brushless dc motors and beltand-pulley setups; take a rod-style morphology; use motors with planetary roller screws; or integrate built-in guides. Electric actuators running closed-loop or with a micro-stepping motor can match force and speed output commands best with feedback to overcome most of the mechanical limitations of rotary-to-linear devices. Some application tips: Establish the design’s power draw and determine whether the machine will draw power continuously or intermittently or both, as that ultimately
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MOTION SYSTEM APPLICATIONS
between the nozzle ends and liquid surfaces prevents the shampoo from foaming. After filling, the bottles continue onward to labeling and capping. One plant employing such machines fills 10,000 bottles per day. Until recently, its machines included pneumatic cylinders to lower the dispensing nozzles to the fill-start bottle depth … and then raise them during filing until the nozzle tips exited the bottle openings. Here’s the challenge: Shampoo dispenses from the nozzles at a constant rate … and the speed of liquid-surface rise is inconstant. The latter is unavoidable because narrower bottle portions fill more quickly than those with larger cross sections. So with the pneumatic system, the liquid rise speed would sometimes outpace nozzle ascent and submerge the nozzle tips — in turn causing (upon nozzle withdraw from the bottles) shampoo drips. These drips required cleanup of the bottle exteriors and conveyor. Now the bottle-filling equipment uses electric actuators
determines actuator size and type. Remember that overly large electric actuators are often less responsive than well-sized units. That said, appropriate safety factors ensure that electric actuators run coolly. Plus, lighter loads on the mechanical components can extend life. Halving load on a leadscrew can extend its life eightfold, for example. Also account for where the actuator will operate. Will it need to withstand exposure to dirt, chemicals and liquids? If so, its O-rings and seals must be made of materials to withstand application contaminants. Another tip: Analyze the final installation point to ensure that the electric actuator can handle side, radial and axial loads.
LINEAR ACTUATORS AUTOMATE SHAMPOO-BOTTLE FILLIN G
Consider the equipment that fills shampoo bottles. Such filling machines use conveyors to transport empty bottles to sensortracked wait positions. Then they insert shampoo-dispensing nozzles into the bottles and slowly raise those nozzles as the liquid rises during dispensing. Holding a constant distance
There were a lot of problems with using pneumatic cylinders to lower shampoo：液面速度 dispensing nozzles to the fill-start bottle depth 変動を見越 and then raise them during filling. For starters, して一定以 内の距離を 確保する。the nozzle tips often dribbled shampoo upon exiting the bottle openings. Electric actuators from IAI America perform far better. ：ノズル速度
Pneumatic cylinders did not allow real-time matching of speeds. Sometimes that caused drips.
Electric actuators do allow real-time matching of speeds.
NOZZLE SPEED LIQUID SURFACE SPEED
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MOTION SYSTEM APPLICATIONS from IAI America for vertical nozzle motion. There are no shampoo drips to clean because the electric actuator continually adjusts its ascent speed to maintain a constant and optimal distance between the nozzles and liquid surfaces. That prevents the nozzles from inadvertently plunging into the liquid (and dripping shampoo upon exiting the bottle). Quality control is also higher as there are no more products rejected on the basis of being underweight due to the presence of bubbles. Finally, the elimination of cleanup saves the shampoo plant labor worth thousands of dollars per year.
AUTOM ATE D FAR M E QU I PME NT US E S RU GG E D LI N E A R C OMP O N E NT S Precision agriculture is the discretization of farming — defined as the analysis of highly variable (and often unpredictable) landscapes to: • Break larger agricultural fields into smaller discrete sections • Quantify the characteristics (such as soil composition, light, and seed spacing) of each section • Adapt to the variations between sections with automated farm equipment to maximize crop yield.
Fully adaptive farming relies on automated equipment. | courtesy of Bishop-Wisecarver
In fact, discretized farming generates lots of data during its mapping and analysis of variations as well as its generation of information about how equipment should compensate for field variations. So only automated (not manual) equipment is practical to execute the highly repetitive, menial, and dangerous tasks required to give individualized attention to each portion of land or crop. Such automated farm equipment often incorporates linear actuators and guided motion components to perform cutting-tool manipulation and crop conveyance, among other tasks. The main caveat is that unreliable components not rugged enough for outdoor farming settings undermine the goals of automation and can even introduce additional complications … including additional maintenance work for farmers. DualVee Motion Technology from Bishop-Wisecarver is designed for durability first — to reliably perform in these harsh outdoor agricultural environments.
AUTOM ATE D V E RTI C AL FAR MS AL SO US E LI N E AR C OMP O N E NTS With a world population of 7.8 billion, food production is a challenge that will only intensify. That’s because the global population is expected to reach 8 billion by 2023 (and 10 billion by 2057) and more than half of the world’s population lives in cities and metropolitan regions. In these settings, agricultural space is scarce, so food must be transported to urban areas from distant regions. Vertical farming is one solution to this compound problem. In vertical farming, enclosed buildings containing vertical racks are used for food production. Such operations reduce production costs as well as CO2 emissions associated with food transport. The vertical arrangements use
Some tractors use linear components from Bishop-Wisecarver — specifically designed to maintain high reliability — in their GPSguided steering systems.
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LINEAR ACTUATORS & GUIDES small spaces in urban areas to generate the greatest possible agricultural yield from a small surface area. The caveat is that the automated machinery for vertical farming must work in a tightly controlled environment that doesn’t lend itself to frequent servicing. Here, engineered plastic components from igus minimize maintenance requirements. Their lubrication-free nature supports FDA compliance and adherence to tight hygiene standards to keep vegetables and fruit meant for human consumption uncontaminated. In fact, the tribo-polymers in igus components are corrosion-free and low-maintenance as well as resistant to dirt, dust, and soil. Taking vertical farming one step further are fully autonomous operaitons. Here low-cost automation systems enable cost-effective vertical planting, harvesting, or packaging throughout the year — along with a quick return on investment. Just consdier Living Greens Farm based in Minnesota. The company converts vacant skyscrapers into vertically arranged farms. These cultivation techniques require special machinery for nutrient supply and irrigation of the plants. A patented traverse system equipped with igus e-chains carries enriched water directly to the plant roots. In on old warehouse in Minneapolis, about 4,000 m2 of space now yields the same quantity of food produced from more than 100 acres of conventional agriculture. Intelligent Growth Solutions (IGS), which is located in Scotland, also uses motion components from igus for automation in vertical farming. One of the goals is to make vertical farming more economical by improving productivity, yield, quality, and consistency and by drastically reducing electricity and labor costs. Vertically arranged IGS systems must be reliable yet low-friction and easy to maintain ... igus drylin linear-guide systems meet all these requirements and ensure trouble-free operation of the system. More than a year after installation of the lubrication-free components, no noticeable wear of the bearing shell is detectable.
Linear components from Bishop-Wisecarver are also found in indoor farming operations.
Vertical farming is considered a promising alternative to conventional agriculture in metropolitan areas. Plastic linear-motion components from igus reduce downtime. | Courtesy of igus GmbH
motioncontroltips.com | designworldonline.com
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MOTION SYSTEM APPLICATIONS
Safety first with friction-element action triggered by spring engagement FRICTION-BASED
brakes and clutches that use springs (typically axialcompression coil springs) for engagement are an exceptionally important class of components. No wonder their variations often justify unique designations that underscore their very specific and essential functions in machine designs. These include certain: • Spring-set brakes • Failsafe brakes • Slip clutches • Safety and e-stop brakes • Holding brakes • Servomotor brakes The power-off designation emphasizes how these particular components default to a spring-loaded condition that brings attached loads to a nonmoving state upon removal of release power. That means the mode of disengagement for these units is quite important as well. In most cases, these brakes and clutches are released in one of two ways: • They are electromagnetically released • They are pneumatically released
The electrification of off-road vehicles propelled by motor-based direct drives (spurred by the advancement of longerlife battery technologies) has prompted innovation in brake and clutch technology as well. RANGER Pursuit EV vehicle image courtesy Polaris
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During electromagnetic disengagement, application of a field on an assembly armature counteracts the spring force clamping together the friction elements and separates friction elements. During pneumatic disengagement, application of power occurs via air pressure in a piston chamber — which in turn counteracts the spring force clamping together the friction elements and releases the friction-based hold … for independent rotation of the axis output. 11 • 2020
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BRAKES & CLUTCHES
SPRING-SET ELECTROMAGNETICALLY RELEASED FRICTION-DISC CLUTCH BRAKE
ARMATURE
FLOATING HUB ATTACHES TO MOTOR
COIL
SPRING ARRAY
In power-off friction brakes, spring pressure forces the friction discs (or elements) into engagement to stop and hold the load. Then an electromagnetic or pneumatic release system spreads the elements apart to disengaging the unit. Such spring engagement offer a key advantage — the ability to serve as failsafe brakes even during power loss. That contrasts with the electromagnetically engaged brakes.
FRICTION PLATES ON ROTOR
Spring-set hub-style brakes mount on the ends of electric motors. In contrast, coupling-type brakes install between the motor and driven load. Where the hub-style brake operates on a precision motion axis (and the braking function affectsperformance) a mode of attachment having minimal backlash is paramount.
Spring Applied Brakes
SPLINE IS ESPECIALLY SECURE
Clutches based on spring force and friction-plate action are often used to transmit mechanical power from a constantly rotating motor-output shaft to some end-of-axis process requiring only intermittent rotation. One of two common variations (in which a clutch hub assembly directly attaches to the motor drive shaft and not the output) includes: • A fixed cylinder or housing with pressure-applying springs and (to apply lateral force for disengagement) either a pneumatic inlet and internal circuit (as well as an exhaust port for quick response) or wiring and a coil for electromagnetic action • A moving (rotating) axis-output sleeve assembly containing friction discs and upon which an output pulley, pinion gear, or sheave bolts • A drive hub enclosed by the housing and sleeve — and having one or more fins (for engagement with the sleeve’s friction elements) as well as an armature if a typical electromagnetically released unit
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MOTION SYSTEM APPLICATIONS
Without any external power, the housing assembly’s springs push together the sleeve’s friction discs and the hub’s fins. Then for disengagement, either electromagnetic or pneumatic-cylinder force compresses the springs to allow the fins and friction discs to disengage. Brakes based on spring force for frictionplate action are by default locked, because in the absence of any external power, mechanical springs hold stationary-side plates, fins, or friction discs in engaged contact with drive-side friction discs. No wonder the failsafe function of many of these brakes is indispensable in medical diagnostic equipment as well as general automation relayed to discrete motion control and servomotor designs such as robotics and mobile equipment complemented by holding brakes.
Don’t eat up valuable time searching for friction brakes, clutches and torque limiters. For more than 45 years, machine designers have relied on us for made-to-order products that meet their exact requirements. We are easy to reach, quick to respond, and deliver both catalog and custom products within reliable lead times. › Pneumatic and mechanical models › Torque capacities to 60,000 lb.in. › Experienced application assistance One call or email connects you with an engineer: USA 859-291-0849 engineering@machiii.com
BRAKES • CLUTCHES • TORQUE LIMITERS
“
“
TOO MUCH ON YOUR PLATE?
Innovations in new and advancing applications are spurring a widening array of brake uses — as well as increased safety for end users. That’s especially true of spring-set electrically released brakes.
These have undergone significant innovation over the past several years as developments in friction materials and spring designs have enabled use in myriad new applications — especially in medical and personal-mobility industries.
Strengths: Spring-set brakes are a top choice for emergency-braking applications on the motor-driven axes of robotic arms, vertical axes, and machines that have the capacity to injure personnel should a power failure occur. That includes escalators, airport-baggage handlers, and elevators. They also benefit motion designs that slow loads with the
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BRAKES & CLUTCHES
motor before the brake engages … and they’re suitable as holding mechanisms as well. There are also countless variants of spring-set brakes and clutches specifically for use on precision motion and servo applications. Many of these have low-backlash hub coupling morphology. That means they have a female spline subcomponent on their friction-element assembly that precisely mates with a matching square, D-shaped, polygon, or hexagon-shaped spline on the electric motor output shaft (or in some cases the driven shaft). Precision-machined splines help minimize (and avoid amplification of unavoidable) radial backlash associated with the internal clearances needed to let the friction elements run free (unengaged) upon application of pneumatic or electromagnetic power. Some units even incorporate diaphragm springs for zero-backlash operation. Otherwise, typical no-load backlash (depending on the component diameter) might be 0.2° to 0.8° or so.
motioncontroltips.com | designworldonline.com
Constraints: The force applied by the springs in spring-set units is a factor that limits the maximum torque rating. In addition, the maximum force of the disengaging system in a spring-set unit must be well matched to the spring force to be overcome during power-on release situations. More basic spring-set brakes and clutches can also introduce excessive impulse and shock loading on precision operations. Case in point: Consider an inclined conveyor with regularly spaced on-off cycles. Here, a power-off brake that is spring-set may suffice to prevent load crashes during power failures. But advanced conveyor installations working to position discrete product of varied size (without jerking) may need multiple deceleration rates via more sophisticated spring-set or other brakes complemented by an advanced motor-and-drive pairing.
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MOTION SYSTEM APPLICATIONS
This FMB rotary table bearing is specifically developed for high-precision rotary-motion tables. It’s less costly than other rotary bearings because it contains fewer components — and necessitates consideration of fewer less tolerances for | courtesy of PM B.V. installation.
Rotary bearings in everything — from miniature tables to railcars BEARING
variations abound to satisfy an array of loads, environments, speeds, expected design life, and more. Consider the bearings and slewing rings in wind turbines. These can reach 2 m in diameter and must sometimes bear hundreds of tons. In contrast are miniature bearings for medical applications. These often go into tiny handheld devices and other compact equipment necessitating bearings of just a couple millimeters in diameter (with rollers that are even smaller).
Shown here is the FMB rotary table bearing once installed. | courtesy of PM B.V.
Some bearings going into equipment subject to washdown have treated steel subcomponents; others for disposable or quiet designs are made of plastic. Industrial machines that endure hot, fast, or lubrication-starved conditions pose their own bearing-design challenges. Some of these benefit from the use of hybrid bearings — those with steel raceways and rollers or balls made from ceramic. No matter the design, each bearing type satisfies specific parameters. Ball bearings use balls to provide low-friction motion between bearing races. When selected properly, they require little maintenance. This feature and their limited heat generation make them indispensable. They are found in everything from skateboard wheels to turbine engines — in aerospace applications, medical equipment, and home appliances.
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BEARINGS On the opposite end of the application spectrum is this SMB188 stainless steel bearing for railway applications — one that includes a magnetic pulsegenerator ring for IIoT functionality. In the railway industry, adding smart bearings will provide operators with real-time, on-board information on bearing health, and allow the detection of early bearing damage. Because train bearings are key elements in the integrity of railway wheelsets, the integration of condition monitoring can significantly impact railway operating costs and train safety. | courtesy of SMB Bearings Roller bearings have cylindrical rollers instead of balls to transmit loads and reduce friction. Thanks to this shape, roller bearings have greater surface contact than ball bearings, so handle larger loads without deforming. Their shape also allows for a moderate amount of thrust load because weight is distributed across cylinder line contacts instead of point contacts. These bearings are common in conveyor belt rollers, turbine engines, transmissions and gearboxes, as well as the mining, food and beverage, pulp and paper, waste-water and marine industries. Needle roller bearings have rollers with lengths at least four times their diameter. The large surface area accommodates high radial loads even in compact designs. Needle bearings often go in compressors, rocker-arm pivots, pumps, transmissions, and other automotive designs. Needle bearings are also common in construction and agricultural equipment, two-cycle engines, outboard engines, and paper-moving equipment. Thrust ball bearings go in applications with mostly axial loads and can handle shaft misalignment. These bearings excel in high-speed aerospace, automotive, and oil and gas applications. Thrust ball bearings also work in machine tools, fluid-control valves, and spindles. Thrust roller bearings transmit load from one raceway to the other to accommodate radial loads. Bearings like these also have a self-aligning capability that makes them immune to shaft deflection and alignment errors. Typical applications include crane hooks, pulverizers, cone crushers and other heavy-load, mediumspeed applications. Tapered roller bearings have tapered inner and outer ring raceways with tapered rollers between them. The rollers are angled so their surfaces converge at the bearing’s axis. These bearings can handle axial and radial loads. Common applications include helicopter transmissions, fuel pumps, and agricultural equipment. Plain bearings don’t have rolling elements. They’re compact and lower-cost bearings for many applications, but automotive and construction are some of the most common. Plain bearings go in automated machine axes and more rugged applications such as hydraulic excavators and more.
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MOTION SYSTEM APPLICATIONS
Contactless energy transfer, cable-free communication open up new possibilities for machine builders ONE
of the more promising recent developments in connection technology is contactless energy and data transfer and its use in the industrial world. Such technology can replace wiring and cables and cable carriers, lowering costs and streamlining designs. For instance, robotic systems are sometimes limited by constraints in automation and drive technology. However, consider the case of a gantry robot that uses contactless energy and data transfer instead of fixed wiring runs and cable carriers. Gantry robots are a tried-and-tested solution for intralogistics material flows within a machine or application. They’re commonly used to detect products automatically, grip them securely and quickly, and take them to their destination. This type of robot is useful in many industries, and can be used for a wide range of product sizes and weights, and distances to be covered. Oftentimes, the lengths of power and communication cables and cable carriers limit the flexibility and adaptability of an existing machine to a new production scenario. But adding contactless energy and data transfer opens up new possibilities.
wear, increase inertia, and have an overall negative impact on both dynamics and energy efficiency due to the friction they generate. Another benefit of contactless energy and communication transfer is that there are no restrictions regarding installation space, cable breakage or limited cycle rates. It’s all made possible by a contactless inductive energy transfer system, including a decentralized power supply module. Depending on the design, this module delivers transmission power between 5 and 11 hp. Another benefit is that throughout the entire load cycle, the robot consumes less than 0.7 hp via the pick-up – even though the horizontal axis alone requires more than 5 hp of acceleration power. The short-term energy requirements are met by the energy storage
LESS NOISE, ENHANCED DYNAMICS, GREATER FLEXIBILITY Contactless energy and data transfer combined with intelligent software and reliable mechatronics can form a fully integrated solution. Using contactless energy transfer, multiple robots can move freely on the same horizontal stretch of rail, greatly increasing the flexibility of the gantry robot. This regularly leads to overlapping sections between robots – ultimately offering a great deal of freedom in terms of machine design and operations. Logistics processes of this kind would not be as easy to implement with cable carriers, because of the additional area that carriers use along the entire distance of the system. Plus, cable carriers generate noise, are subject to
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Real-time communication on the robot gantry takes place via an optical connection using EtherCAT.
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MOTION SYSTEM APPLICATIONS
units that draw their power with cables, in contrast, are tied to their section. As a result, the associated resources become movable and systems as a whole are more flexible and productive. Entirely new machine concepts can be created based on this approach.
The intelligent energy supply with the dc link buffer via double-layer capacitor packages ensures the robots can be hooked up to a 230-V connection.
unit, a double-layer capacitor package that takes care of the primary energy supply to the robot with a dc link voltage of 100 V. The typical travel profiles of a gantry robot, which involve alternating acceleration and braking phases, led to the idea of retaining the regenerative energy generated during braking within the process instead of dissipating it via resistors. The energy storage unit absorbs this braking energy and also functions as a booster when the gantry’s drives accelerate at 20 ft/ sec2. The contactless energy transfer and storage system only has to compensate for the system’s mechanical efficiency losses, which amount to around 0.7 hp. Unlike the familiar dc link connection of multi-axis applications, which is located in the central control cabinet, each unit is enabled to store energy independently. This makes it easy and convenient to scale the system.
OPTICAL REAL-TIME COMMUNICATION
The automation provider opted to use the real-time Ethernet protocol EtherCAT in the gantry – once again dispensing with cables by implementing an optical connection to the mobile units. The drive data can be delivered to the robots via data light barriers. There are no separate motion controllers in each robot as one does the job of running the whole robotic system. With each cycle taking 1 msec, the optical system has practically no latency periods when transmitting the interpolated position setpoints to the inverters or feeding back the relevant actual values. Communication for the functional safety technology works in the same way. The application uses a central safety controller for all robots and the machine as a whole. This safety controller communicates directly with the SEW Eurodrive MOVI C automation controller via EtherCAT using the EtherCAT FSoE (Fail Safe over EtherCAT) protocol. This setup lets both controllers share data with ease, simplifies programming considerably, and offers excellent conditions for diagnostics and debugging. The seamless integration of the FSoE safety master and the EtherCAT data light barrier are integrated into a comprehensive automation solution including motors, electronics and visualization.
C ABLE-FREE C OMMUNIC ATION The robot gantry’s contactless energy transfer system, which eliminates the need for restrictive cables, also extends to the communication processes. Here, an EtherCAT data light barrier transfers the interpolated position setpoints from the central motion controller to the four servo inverters in the moving housing box at 1 msec intervals. A motion controller calculates the complex robot motion control – and can do so for up to four robots at once. Motion control involves performing calculations and coordinating the robots to prevent collisions. If a machine in a production network requires double the material flow output, the gantry system gives users the option to move a robot from another section on a flexible basis. Handling
In the MOVI C automation controller from SEW Eurodrive, data from the FSoE (Fail Safe over EtherCAT) master is routed and mapped to the relevant robot axes.
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Your Designs, On Time Shorten your lead times—even for custom cylinders
FABCO-AIR A member of Festo Group
F Series
Pancake II
OEM NFPA
• Configurable general purpose cylinder • Twelve bore sizes (5/16 to 3”) and standard strokes to 32” • Options include adjustable air cushions, Viton® seals, rod wipers and more • Support for food packaging or washdown environments
• Robust compact actuator • Eight bore sizes (1/2 to 4”) and up to 9” stroke standard • Composite body enables impact resistant, self-lubricating operation • Composite rod bearing for reduced wear and increased load capacity
• Cost-optimized NFPA interchangeable pneumatic cylinder • Five bore sizes (1-1/2 to 4”) and strokes up to 48” standard • Adjustable air cushions and magnet for position sensing standard • Variety of NFPA mounting options
www.fabco-air.com
MOTION SYSTEM APPLICATIONS
MELSERVO-J5 components from Mitsubishi Electric support fast communications and a 3.5-kHz response rate for precise and responsive motion with short settling times. Use of CC-Link IE TSN facilitates IoT functions and time synchronization across all connected devices at 1 Gbps. Series components also satisfy single-axis to 256-axis systems — with all motion modules programmable in a single software environment.
controls and drives address covid and more MOTION
controllers range from single-axis smarts to programmable automation controllers (PACs) that synchronize hundreds of axes and plant data communications. These precision command centers are central to today’s motion-system innovation. Just consider how controls deliver flexibility to packaging applications ...
Bosch Rexroth’s ctrlX open automation platform now includes advanced I/O to accommodate various field and control interfaces. That in turn supports horizontal and vertical integration and expands the functions of ctrlX CORE controls.
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Simplified Motion Series
The simplicity of pneumatics combined with the advantages of electric automation The Simplified Motion Series is ideal for movements between mechanical end positions with a reduced number of parameters. • Operation without any software based on the plug and work principle • Easy and quick commissioning without a computer, software or other accessories • Connection via IO-Link for enhanced functionality including diagnostics • Simple control with 2 digital inputs for basic functions or enhanced control with IO-Link for additional functions
festo.us
MOTION SYSTEM APPLICATIONS
This Mikron mask-making machine (which fits in a 20-ft shipping container) can produce 50 to 100 protective masks a minute. CMMT servo drives and EMMT electric motors from Festo connect to the machine’s central controls. Other Festo components on the machine include DFM guided drives (shown here preparing the earloops) as well as ADN pneumatic cylinders, MPA valves, MS6-SV-E safety valves, and DSNU round cylinders … all components in stock worldwide and available within 24 hours. Such availability is key in systems for addressing COVID-19.
MELSERVO-J5 ac servomotors, amplifiers, and motion controls from Mitsubishi Electric Automation allow (among other things) a quick-tuning function for tuning of servo mechanisms in about 0.3 seconds. Here, the servo amplifier sets the speed loop gain and suppresses machine resonance through the servo on command. No tuning experience is required because gain values are
automatically generated … reducing machine setup time and effort. Additional functions and features include an advanced vibration suppression function, multi-axis servo amplifiers, expanded predictive maintenance capabilities (powered by Maisart AI) and a 31.25-μsec communication cycle time with multi-network compatibility with CC-Link IE TSN and EtherCAT.
In fact, EtherCAT (with PC-based control) will also support the advanced motion of more than 3,000 axes on the Giant Magellan Telescope (GMT) in the Chilean Andes once the telescope construction is completed in eight years … and prevent obsolescence with standardization and upgradability. The GMT will capture images of astronomical objects sharper
Supporting the advanced motion systems of the Giant Magellan Telescope (GMT) optics will be a 1,300-ton precision base structure from Ingersoll Machine Tools and MT Mechatronics of the Camozzi Group. The precision steel optical support structure will allow frictionless movement using hydrostatic technology.
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MOTION CONTROLS & DRIVES
Precise. Efficient. Quiet. Economical.
Engineers building the GMT are using off-the-shelf industrial components in their telescope design — including Beckhoff CX2020 CPU and EtherCAT I/O modules as well as AS1020 stepper motors. EtherCAT will support the GMT’s systems for its primary mirrors, atmospheric dispersion compensator, enclosure, mount, and building automation. than currently possible by reducing distortions introduced by the terrestrial atmosphere. Besides rotating the telescope’s 22-story-tall enclosure, flexible mirrors must be moved with the utmost precision to implement adaptive optics and collect images with the highest possible resolution. 170 pneumatic actuators support and move each primary mirror. Here, EtherCAT provides flexible topology and scalability, along with the ability to incorporate up to 65,535 EtherCAT devices in one network to satisfy GMT system specifications. Functional Safety over EtherCAT (FSoE) also imparts functionality to the telescope’s interlock and safety systems. More specifically, FSoE provides the GMT with safety-rated TÜV-certified communication over standard EtherCAT networks as well as numerous options for distributed safety I/O based on Beckhoff Automation’s TwinSAFE I/O modules. It also allows integration with the Beckhoff engineering environment and industrial PCs (IPCs).
Planetary Screw Assembly PLSA delivers high positioning accuracy and repeatability Compact and cost-effective, the Planetary Screw Assembly PLSA screw drive system from Bosch Rexroth combines high load capability and precise endpoint accuracy. For applications including machine tools, welding systems, plastic injection molding machines and industrial robots, Rexroth’s economical PLSAs offer an efficient solution for machines requiring up to 25,000 pounds of pressure.
Want to move heavy loads with greater accuracy? Learn more at www.boschrexroth-us.com/plsa
DESIGN WORLD — MOTION
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MOTION SYSTEM APPLICATIONS
Conveyor functions as varied as applications CONVEYORS are core to material handling … for transporting packages as well as improving workflows and even interfacing with other automated systems. Just consider the requirements placed on zero-pressure accumulation conveyors — systems with precision controls to prevent products from bumping or even touch while conveying for the prevention of damage to expensive workpieces and fragile products. Such designs require IoT connectivity for data sharing as well as precision motion and optimized efficiency.
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These and other conveyors for discrete product transport benefit from customization to satisfy requirements — including support frames; chain and belt size, morphology and material; controller, drive, and motor or motors; mode of engagement with the drive; encoder, vision, and switch feedback; tracks, bumpers, and gates; and HMIs and plant-level IT integration. For example, warehouse automation requires ultra-fast sorting and tracking … and conveyors with servomotor functionality integrated with inspection stations fitted with machine vision. Or consider pharmaceutical manufacturing — now a trillion-dollar industry and expected to grow to address COVID-19 — with especially stringent regulations. Here, conveyors must deliver top-notch warehouse automation functions and have stainless and aluminum parts to pose no risk of contamination to expensive pharmaceutical products such as pills. Likewise, medical-device manufacture must adhere to FDA regulations
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CONVEYORS
The DC Platform from Interroll is a series of 24-V or 48-V components to build power-roller-based conveyors for operation flexibility. Installations based on these offerings can precisely position totes and goods to complement robotics … or work as conveyors commissionable without a PLC. The 48-V systems cut the need for power supplies in half (compared to comparable 24-V installations). The RollerDrive EC5000 in the lineup comes in 20-W, 35-W, and 50-W versions for the transport of light or heavy goods. Other large-diameter, IP66, Deep Freeze, and CANOpen-connectible roller options abound.
that dictate equipment-sterilization schedules so conveyors in these applications withstand harsh washdowns. Another example is how some highly engineered flat-top conveyors streamline still other material handling. Among the many varieties of conveying systems, flat-top conveyor chains perform like belts but can also convey, transfer, accumulate, meter, elevate, and lower items of various sizes and shapes. The VersaFlex conveyor from mk North America is one such flat-top chain conveyor system for complex design needs. It replaces the company’s SBF-P 2254 conveyor line … and excels as a pallet-handling conveyor system in many industries. Conveying the product on a pallet achieves a more streamlined approach to material handling which in turn maximizes manufacturing productivity, flexibility, and product quality. Consider another way in which conveyors improve upon traditional arrangements — in production. Here traditional work areas are separate from parts warehouses — and external logistics integrate only with warehousing operations. In some instances, automatic guided vehicles (AGVs) might travel the plant floor and feed assembly or finishing lines at regular intervals. Then personnel at stations execute fairly specific operations — picking pieces and finishing assemblies, for example. But automated plants today are looking to satisfy end-user demand for increasingly customized product. Just consider how amazon.com offers a huge array of choices for nearly any product type imaginable. That demands far more items in any given warehouse than in the past — and facilities that can handle the exponential rise in item numbers. Here and in similar operations with comparable complexity, overreliance on manual labor adds too much cost into the final delivered-product cost. Using AGVs to supply all the items or parts to work or assembly stations would quickly choke even expansive operations with unsafe and insufficient traffic. Totally automating
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POWER TRANSMISSION-PART CONVEYING
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MOTION SYSTEM APPLICATIONS
VersaFlex coveyors from mk North America are available in three different chain width sizes. They can also convey small pallets. Key benefits include the ability to easily and cost-effectively integrate into existing production processes and expand as needed.
Versatile. Flexible. Modular. Flat Top Chain Conveyors
finishing processes using robots is often unsuitable or impractical. Conveyors are a great solution to these limitations. Conveyors free personnel from rote jobs so they can focus on more complicated factory tasks — supplanting bins, AGV part racks, and a mishmash of unergonomic pallets and boxes around a work cell with more efficient presentation of parts to be processed. Pioneered by the Toyota’s World Class Manufacturing (WCM) concept, conveyors complement use of what’s called the Golden Area — the immediate area around a worker in which no time is wasted. In addition, conveyors support operations with exceptionally numerous item variations and delivery requirements as well as those that need automated order tracking.
www.mkversaflex.com/dw The perfect solution for complex layouts: • Pallet or product handling • Inclines, curves and loops • Diverts and merges
®
better products. better solutions. (860) 769-5500 | info@mknorthamerica.com
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COUPLINGS
Coupling types complementing servo applications COUPLINGS
for servo applications usually connect precision drives to sensitive loads, so they cannot induce any error. That’s why servocouplings should be zero backlash — to prevent issues with timing and predictability (not to mention failures due to hammering on reversing axes). Couplings for servo applications must also have high torsional stiffness while imparting slight forgiveness of misalignment (within specifications) of rotating shafts, even while holding transmitted rpm steady to motor output rpm. But these are just a few servocoupling considerations. Consider a typical application for servocouplings — to connect a servomotor to a ballscrew. Here, couplings with low inertia let the axis deliver faster acceleration and deceleration without unnecessarily degrading overall system efficiency. In fact, couplings for servo designs must often compensate for subtle power-transmission issues to minimize errors down to 1 arc-min. or lower. That’s especially true where servo systems take the form of exacting positioning axes. motioncontroltips.com | designworldonline.com
The 2,500-seat Théâtre du Chatelet in Paris has undergone many restorations and upgrades since its original construction in 1862. In 2019, the theater reopened after a €31 million renovation.
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MOTION SYSTEM APPLICATIONS
Here’s a more complete list of parameters to consider for proper coupling operation in such designs: Coupling type: Couplings shouldn’t be the last motion component specified because proper servo-machine function relies on having a suitable coupling in place. Torsionally rigid options (suitable for motion designs) include specialty bellows couplings, rubber-jaw couplings, and disc couplings. Curved-jaw couplings have good damping characteristics to optimize performance of axes with quick acceleration and deceleration. Elsewhere, both disc-type couplings and certain bellows couplings excel on high-speed axes. Other offerings abound to serve other design objectives. One caveat on coupling type though: Never use rigid couplings to replace flexible servocouplings on axes where the latter seem to fail frequently. Here, the issue is most likely insufficient alignment between the motor-output shaft and next component in the powertrain. There’s sometimes a misconception that rigid couplings are exceptionally strong, so can address issues in such situations. The fact is that rigid couplings only work when shafts are perfectly aligned, because these couplings transmit to connected motion components (potentially extreme) forces that arise from misalignment. Sizing for torque (and speed): After specifying the coupling type, the design engineer must select a coupling size. This is heavily dependent on axis speed (rpm), the levels of torque the axis must transmit, and the service factor the application requires. Axes that transmit steady torque are simpler to specify; in contrast, axes that transmit variable torque need additional consideration. Here, define the application’s average operating torque and the peak torque. One tip to avoid servocoupling oversizing: Quantify actual system requirements and base coupling selection on those values — and avoid defining a whole axis by the connected gearmotor’s peak torque output. Damping capabilities: Disc couplings, certain bellows couplings, and high-gain rubber-type couplings are all options for coupling-based damping in servo applications. In fact, the most demanding servo applications have in recent years spurred improved response frequencies,
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Zero-Max ServoClass couplings outperform jaw and spider and bellows couplings in many demanding servo motor applications. That’s because spider elements can deteriorate over time from heat and fatigue and allow for torsional windup in high-torque applications. ServoClass couplings’ flex-disc construction imparts high misalignment capacity and torsional stiffness to avoid such problems.
Huco Flex-Ni electroplated nickel bellows couplings provide rotation position integrity with high torsional stiffness. | courtesy of Altra Industrial Motion
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COUPLINGS
but vibration (and hunting) arise with high gain settings on assemblies using torsionally stiff couplings. Shaft connections: Most servocouplings connect shafts with clamping or locking mechanisms (and not keyways). Though keyways are often offered as an option to prevent shaft slippage, the truth is that they can be a liability — adding concentrations of stresses in shaft connections, unnecessary cost, risk of imbalance, and other potential drawbacks.
FOR REDUCING MACHINE DOWNTIME
C OUPLIN G-MOUNT ENC ODERS FOR ACCURACY French stage-equipment manufacturer BC Caire needed reliable and theaterquiet powertrain components for new scenery winches at the 2,500-seat Théâtre du Chatelet in Paris. Electric motors and winches were installed to lift heavy set decorations and large video screens at speeds to 1.60 m/sec for quick scenery changes. Advanced motion controls let one operator simultaneously maneuver 14 individual scenery lifts at full speed and load. The winch-braking solution (for static holding and emergency stopping with no audible noise when braking) are Warner Electric ERS FENIX 10 electricallyreleased brakes. Other Altra Industrial Motion products in the upgrade include Stromag Series 51 limit switches and EZX tooth clutch assemblies (on each winch drive) and Huco Flex-Ni electroplated nickel bellows couplings. The latter mount encoders to eliminate misalignment problems. More specifically, the FlexNi couplings provide rotation position integrity with high torsional stiffness while still accommodating lateral and angular misalignment due to low spring rates in these directions.
DESIGN WORLD — MOTION
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TORQUE LIMITER 9 Heavy duty construction 9 Reliable torque overload release 9 Resets in minutes
THE COUPLING. RW-AMERICA.COM
MOTION SYSTEM APPLICATIONS
New encoders wrap around axes MYRIAD
features have been added to all rotary-encoder subtypes in recent years. These rotary encoders include those that output incremental or absolute signals to provide feedback on position and speed. Incremental signals are trains of high and low waves indicating movement but not specific position. In contrast, absolute encoders do indicate position of the rotary axis being tracked along with movement. Mechanical encoders are actually more like rotary switches but with a digital output. They are common in consumer products for knob tracking and in medical and fitness equipment and avionics. Resolution is defined in terms of angle of throw — for a number of positions — such as 30 positions for a 360° turn for example. Rotary encoders for true motion-control applications include capacitive encoders employing low current. These are an efficient option using a high-frequency transmitter that sends signals intermittently modulated by an etched disc before they get to a receiver. That receiver reads the capacitance variations and an ASIC translates them into angular values with resolution to forty ninety-six steps per revolution. The most common rotary encoders today though are optical encoders. Early versions had fragile glass discs between a light source and sensing head. Increasingly common today are more rugged versions. The disc can be etched metal, marked tempered glass, or engineered plastic.
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Sp Robotics demand very high levels of repeatability — even down to 0.1 mm in some cases. POSITAL FRABA hollow-shaft encoders can deliver this performance on six-axis articulated (SCARA) industrial robots and cobots. They have center bores of 30 or 50 mm (to route cables and media hoses) and are 17.8 mm thick with an O.D. of 80 mm and weight of only 110 g.
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ENCODERS
The MSAC200 flexCoder absolute encoder from SIKO allows for a customer-specific ring diameter and type; integration into small spaces; and resolution to 21 bits. Absolute position feedback is via an SSI or BiSS-C motor-feedback interface. Optional analog real-time sin/cos 1-Vss output serves industrial and medical applications needing motor feedback for automation or robotics tasks.
Integrated electronics have made these encoders more rugged as well. For example, Opto-ASIC technology from Encoder Products Co. is a single chip combining all sensor-board components including the photosensor on one circuit. That boosts resistance to particulates and electrical noise. Magnetic and magnetostrictive encoders have also seen increased use in recent years in part thanks to new designs based on such sensing. Common iterations of these sensors have an array of magnetic strips around a wheel. Two channels on the sensor tracks pairs of strips and output differential signal. Some designs use embedded microprocessors running signal handling software as well — to get accurate and dynamic response rivaling optical designs. Taking the measurement tasks from opto-electric components to solid-state electronics in some cases means these encoders can be smaller and more reliable. Plus users can change the performance characteristics of these encoders more easily through software updates rather than physical changes. So, it’s easier to tailor such encoders to projects with fewer if any design compromises. This plays into a broader industrial trend to Big Data and the internet of things … as well as the trend to more preventative maintenance.
For Motion Feedback in Industrial Automation, EPC has your solution. Innovation in motion feedback since 1969 For 50 years, EPC has been providing encoder solutions for reliable motion feedback.
Thru-Bore Encoders
Programmable Encoders
Whether it’s an application for servo labeling, heavy-duty packaging, material handling, or any place where motion feedback is required, we have the solution you need and the expertise to help you find it.
Specializing in custom encoders, fast When you call EPC, you talk to real engineers and encoder experts who can help you spec the right encoder for your motion control application. And we’ll get it to you fast. Standard lead time is just 4 - 6 business days, with same-day expedite options available on many models.
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MOTION SYSTEM APPLICATIONS
ABSOLUTE ENCODERS WITH IO-LINK
Smart Encoder Ready for Industry 4.0
Simplify Your Communications System Magnetic Multiturn Sensing Without Gears or Batteries Perfect for Factory and Process Automation Aplications Condition Monitoring via Vibration and Temperature Sensor
The Versatility Champs
Physical permutations for rotary encoders abound. These include various seal, bearing, and housing options, as well as modular setups. Just consider hollow-shaft encoders with an open ring shape to install around shafts or cabling on servomotors, drives, and other rotating axes (such as ROTOR robotic joints) to report position. Most are single-turn devices. In contrast, POSITAL’s capacitive hollowshaft kit encoders can track multiple turns using an integrated rotation counter that records every single STATOR revolution sans external power supply or batteries or even complex gears. Instead, the encoders use Wiegand energy harvesting already core to so many POSITAL FRABA encoders. The technology converts rotational motion into electrical impulses. More specifically, mechanical motion is captured as magnetic energy in the components’ Wiegand wire and then released as pulses of electricity to power a rotation counter. One catch is that traditional Wiegand harvesters rely on permanent magnets mounted on the centerline of the axis drive shaft … so the hollowshaft build necessitated a totally new turn-counting design. That’s why these new encoders have four permanent magnets on the rotor circumference for a stable magnetic field for the Wiegand sensor in the stator to detect and use. With every 360° rotation of the rotor magnets, a Wiegand wire in a copper coil generates a pulse of electric current that activates counting electronics — precisely recording every revolution. The multiturn counter has a 43-bit memory that provides a measuring range of almost nine trillion revolutions. POSITAL has supported the motion industry’s increased use of magnetic encoder technology (instead of optical) but magnetic systems are hard to implement in hollow-shaft designs. That’s why the component manufacturer employs capacitive measurement technology in its new hollow-shaft encoder. Capacitive encoders have a flat rotor and flat stator with patterned conductive surfaces serving as capacitor plates. As the rotor turns, these surfaces experience capacitive-coupling variations. The variations modulate the amplitude and phase angle of highfrequency electrical signals through the system. ASIC processors collect the resulting output and decode them to accurately determine rotor angular position. Then the data goes onward to a central controller via open-source SSI or BiSS C interfaces. Capacitance is averaged around the component’s full rotor and stator circumference for feedback that’s relatively immune to dust, moisture, and minor alignment errors.
In another encoder design to optimize robotics and motor-driven axes on automated machinery, a sensor and rule adapt to the position and shape of the axis. Called flexCoder technology from SIKO, the most significant task is simply attaching the rule to the shaft to be tracked. Otherwise the system allows use of a standard magnet ring with a sensor array and stackable electronics adaptable to the design housing. Ring diameters are to 44 mm and repeatability is to 0.01° … high installation tolerances (and therefore simplified installation) are possible with the distance between the sensor and rule less than or equal to 0.6 mm and an axial tolerance of ±0.2 mm.
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GEARS & GEARSETS
Miniature gearing and planetary gearing put to good use GEARS
function in an array of power-transmission applications. They are the natural complement to electric motors in industrial and consumer designs. Consider some examples: Amusement rides to consumer-grade home printers make use of spur gears. These roll through meshing for up to 98% or higher efficiency per reduction. The only caveat is that they exhibit tooth sliding and noise due to initial tooth-to-tooth contact and audible shock loads.
This subassembly is from a maxon GPX 22UP X-series 22-mm diameter planetary gearhead. Notice how the planet gears spin on precision needle bearings instead of higher-friction plain bearings. This and other features give the GPX UP planetary gearbox higher continuous and peak torque capabilities than comparable designs — for top efficiency, service life, and smoothness during back-driving … even in | courtesy of maxon multistage iterations.
motioncontroltips.com | designworldonline.com
Helical gear reducers are costlier than spur sets but work in designs needing high horsepower and efficiency. Textile machinery, conveyor drives, rolling mills, and elevators all use helical gearing to engage gradually over tooth faces for smooth operation and high load capacity. The only caveat is that the machine setup must include framing or supports to resolve thrust loads originating from the gears. Non-parallel and right-angle gears go into motion applications for material handling, aerospace and defense, packaging equipment and food-processing machinery. Input and output shafts protrude in different directions; gear teeth are worm, hypoid, bevel (straight, spiral or zerol) as well as skew or crossed-axis helical. Common bevel gearsets often go into material-handling and packaging equipment. Hypoid gears (useful for high-toque applications) are like spiralbevel gearsets, but output and input shaft axes don’t intersect — and that simplifies integration of supports. Common in aerospace, zerol gearsets have curved teeth that align with the shaft to minimize thrust. Speed reducers work with an array of motors. These gearsets alter the torque of a motor — usually as an increase proportional to rpm reduction. Common in material-handling setups, shaft-mounted gear reducers come in designs that use special couplings to address reactionary torque. Other shaft-mounted reducers actually mount to the machine housing (especially in machine setups with surrounding enclosures) so the input shaft doesn’t support the reducer. 11 • 2020
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One force-feedback application is that of a surgery robot. Here, maxon GPX UP gearboxes cleanly pass torque either from the input or output side … resulting in a superior haptic system and surgical result. | courtesy of maxon The American Gear Manufacturers Association (AGMA) defines the term speed reducer as sets with pitch-line velocities not exceeding 5,000 fpm or pinion speeds not exceeding 3,600 rpm. Consider worm-gear reducers. These typically go into low to moderate-horsepower motion applications because they have high ratios and output torque but are cost effective and compact. Most worm gears are cylindrical with teeth of consistent size; some worm-based reducers have double-enveloping tooth geometry (in which pitch diameter is deep and short and then deep again) to boost tooth engagement. Metal cutting and forming machinery, construction equipment, and packaging machinery all benefit from the low backlash of this gearing type. To illustrate, printing-press rolls hold tight print registration at high speeds thanks to the ability of double-enveloping worm gearing to withstand shock and extreme acceleration. The gearing’s low inertia also lets presses start and stop more quickly than those with multistage gearing. Gearheads, much like gear reducers, are useful where applications
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call for high torque at low speed. They reduce a load’s reflected mass inertia, so ease the acceleration of big loads ... which in some cases, even lets machines run off smaller motors. Gearheads range from basic spur gearheads to complex planetary gearheads and harmonic gearheads, all exceling in select applications. The latter (also called strain-wave gearing) is for special speedreducing applications. This gearing excels in robot-arm articulation, medical equipment, and offshore drilling. Strain-wave gearing helps designs with zero backlash and high torque density. Much machinery integrates servogears into application-specific electromechanical arrangements, and several of these arrangements are common enough to have their own labels. Gearmotors (most useful in machines that move heavy loads) include a gear reducer integrated with an ac or dc electric motor. Gearboxes are contained gear trains; planetary gears are a common form. Planetary gears often go in servo systems. Usually, the planet gears mount on a movable arm that rotates relative to a sun gear. In most applications, an outer annulus meshes with planet gears.
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Ultra-Lightweight, Compact Gear Units
NEW!
Introducing a new series of ultra-lightweight gear units featuring a newly engineered lightweight structure with an ultra-compact shape. Ideal for use on end of arm axes for small industrial and collaborative robots, the CSF-ULW is also well suited for general industrial machinery where weight is a critical factor. The two smallest sizes, 8 and 11, are available today. Other sizes coming soon! • Zero Backlash • High Accuracy • Ultra Lightweight • Ultra Compact • Reduction Ratios 30:1~100:1
• Super Flat Configuration, 19mm (size 8); 21.5mm (size 11) • Outer Diameter: φ 42.5mm (size 8); φ 50.5mm (size 11) • Weight: 90g (size 8), 150g (size 11)
42 Dunham Ridge, Beverly, MA 01915 | 800.921.3332 | www.HarmonicDrive.net Harmonic Drive is a registered trademark of Harmonic Drive LLC.
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MOTION SYSTEM APPLICATIONS
Planetary gearsets offer applications advantages over other gearsets, including multiple kinematic combinations, power density, big reductions from compact setups, and pure torsional reactions. Planetary gearboxes also boost overall design efficiency. Losses never exceed 3% per stage, so the sets transmit most energy for productive motion output. In applications driven by servo systems, gearboxes also reduce settling time … which is otherwise a problem when load inertia is high compared to motor inertia. Consider the applications of one miniature line of planetary gearing. maxon’s new gear planetary X-series Ultra Performance (GPX UP) is now a standard product offering for configurable X-drive assemblies. So now the GPX variations include: • the GPX A (with metal planetary pins standard) • the GPX C (ceramic planetary pins for increased torque and life) • the GPX LN (for reduced noise) and the GPX LZ (for reduced backlash) • the GPX HP (for high power and increased torque capacity) • the GPX UP (for ultra performance in the form of smooth back-drivability and top efficiency GPX UP planetary gearing already works in Mars rovers and Formula 1 racecars to deliver high torque, ruggedness, and efficiency. Normally miniature gear assemblies rotate the planet wheels and gears on greased steel or ceramic pins (which serve as simple plain bearings). In contrast, GPX UP gear assemblies actually include tiny needle bearings at these rotary axes — for rolling instead of sliding friction (and less friction and heat generation). GPX32 UP three-stage assemblies get efficiencies to 90% — far better than the 70% or so of comparable designs. So if fitted with an otherwise identical motor and controller, the entire system can output 30% more torque and power at output … or need 23% less input to generate a given output. If the motor happens to be
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a brushed motor, that extends the brush and overall system life. Plus more efficient gearing lets the motor operate at a higher location on the efficiency versus torque curve … or allow use of a smaller and lighter motor with control electronics. Such efficiency rom such a small component is particularly useful in battery-powered motion designs. Having a needle bearing (and not a plain bearing) at the planetary-wheel ID axle means the assembly runs more coolly as well … which is helpful on handheld medical instruments. Cooler operation also extends the life of the gear assembly’s lubricant — with less thermal stress and abrasive behavior through abraded metal particles and lubricant agglutination … so the GPX UP gearbox lasts 11 times longer than comparable competitor models. The GPX UP also excels in haptic (force-feedback) applications because its smooth-turning planet gears allow repeatable back-drivability — that turning the shaft from the output side of the gearbox. So torque feedback via the GPX UP to the motor on the gearing’s input is consistently proportional to the load.
This 22-mm diameter GPX UP planetary gearbox was designed for an aerospace application. Notice how the planetary gears spin on needle bearings and not plain | courtesy of maxon bearings.
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MOTION SYSTEM APPLICATIONS GE ARING AND OTHE R MOTION IN E X TRUSION EQUIPME NT Parts fabricator and machine builder Meyer Enterprises recently built a machine that turns PTFE tubing into medical-grade heat-shrink tubing. Key to the design is a puller assembly capable of pushing and pulling tube through the equipment during processing. In fact, two Versa Caterpillar Feed C-22 non-motorized puller assemblies tug material through the heat process — one in and the other out. Optional pneumatic operation of the belt booms along The Versa C-22 caterpillar feed a constant centerline applies even clamping force over allows control of the product without deformation pressure applied to the — key when manufacturing product being pulled. medical-grade plastic products. In contrast, machine builder Simonds Industries uses motorized Versa PM-22 pinch-roll pullers to manufacture bandsaw blades and cutting tools. The pullers take bandsaw blade material off a 300-ft coil and pay it off to the required lengths for cutting. The motorized PM-22 puller assembly includes the motor, drive, control, and gear reducers … modified to allow feeds to 350 ft/min.
Here are various maxon GPX planetary-gear offerings.
Traditionally-built planetary gearheads can’t guarantee smooth back-drivability or consistent load interpretation through the gearbox because of fluctuating efficiency as well as variable tolerance stackups between gearbox internals and the potential cocking of planet gears.
T WO H AP TI C S APPLI C ATI O N E X A MPLE S Consider a specific haptic application — that of electronic fly-by-wire flight control. In these systems, a pilot’s steering movements aren’t transferred via conventional mechanical or hydraulic actuators. Instead, electronic transmission occurs via a feel (force feedback) motor assembly in a joystick control column. Such haptics-generating motor assemblies benefit from gearboxes capable smooth back-drivability and simultaneously generating torque and force based on joystick position. Another haptics application is that of surgical robots for minimally invasive micro and telesurgeries. Doctors performing surgery through these robots dynamically and instantaneously feel forces equivalent to those exerted by the robot end effectors. Here, gearboxes with smooth back-drivability are essential. GPX UP gear assemblies deliver on this parameter even on axes needing gear ratios that necessitate two or three planetary stages. Traditional gearing exhibiting uneven or sticky back-drivability is mechanically noisy and unusable in these robots.
Blend-Pro has a customized caterpillar puller with silicone belts on its Versa machine infeed. A roller encoder measures the speed of material exiting the extruder to let puller speed match.
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YOUR CUSTOM SOLUTIONS ARE CGI STANDARD PRODUCTS
Advanced Products for Robotics and Automation CGI Motion standard products are designed with customization in mind. Our team of experts will work with you on selecting the optimal base product and craft a unique solution to help differentiate your product or application. So when you think customization, think standard CGI assemblies. Connect with us today to explore what CGI Motion can do for you.
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MOTION SYSTEM APPLICATIONS
MICROMOTORS GIVE ROBOTIC HAND A BOOST AMONG
the changes to small motor design over the years has been the use of powerful rare-earth magnets to increase power density, making for smaller and more powerful motors. These motors are finding their way into medical devices, robotics, as well as the intersection of these two. Case in point; a robotic glove. Ironhand from the Swedish company BIOSERVO TECHNOLOGIES is a soft robotic glove that strengthens the human grip. The gripping force support of the individual fingers is made possible with FAULHABER drives. Musculoskeletal disorders are a common occupational disease in the EU and North America and are one of the most common causes for long-term absence from work. Work-related upper-limb disorders annually cost 2.1 billion euros across the EU and are responsible for 45% of all occupational diseases. Wearables, clothing enhanced through technology such as the Ironhand, offer an approach for reducing these injuries. Improved ergonomics at the workplace are increasingly important – both for healthy people as well as for those who are already physically disabled. In addition to solutions that make the actual workplace, meaning the workbench, the desk or the assembly line, more ergonomic, companies increasingly rely on solutions that can be used to augment people. Exoskeletons that are worn on the body like clothing are one solution.
MORE POWER IN THE HAND This is where the Ironhand, the soft, active exoskeleton for the hands and fingers, comes in. Normally, a gripping action is made possible by the muscles in the lower arm and hand. These muscles pull on tendons, thereby moving the fingers. Ironhand functions in a similar way; pressure-sensitive sensors in the fingertips of the glove detect the gripping action that the user performs with their hand. A computer integrated in the system calculates the
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The 1741 ... CXR series of dc micro motors from FAULHABER feature a diameter of just 17 mm and length of 41.2 mm, making them especially suitable for applications with space limitations. additional gripping force necessary and small servomotors pull thin cables in the fingers. The higher the pressure on the sensors, the more power delivered by Ironhand. The settings of the glove can be adapted according to personal preferences as well as the type of work being performed. Data functions enable a digital risk assessment of the hand and the integration of the user in an Industry 4.0 / factory-of-the-future concept. Grip-intensive applications with high ergonomic risk can be identified by analyzing the data during practical work and users can take appropriate countermeasures. To control the individual fingers, BIOSERVO uses FAULHABER’s 1741 ... CXR series of dc micromotors with graphite commutation in their Ironhand. The series combines power, robustness and control in a compact form. This is ensured by graphite commutation, highquality neodymium magnets and the tried-and-tested winding of the FAULHABER rotor. The powerful neodymium magnet gives the motors a high power density with a continuous torque ranging from 3.6 to 40 mNm. The impressive performance data and the compact size open up a wide spectrum of possible applications at an optimized price/ performance ratio. The glove is available in four different sizes and can be worn by left- and right-handed users. The battery pack, which is worn like a backpack, contains both a computer unit as well as the motors that motioncontroltips.com
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The Ironhand from Swedish company BIOSERVO TECHNOLOGIES is a soft robotic glove that strengthens the human grip using dc micromotors from FAULHABER.
control the individual fingers. Users can preset various profiles that contain different combinations of sensor sensitivity, force, finger symmetry and locking tendency. Users can change the profile by pressing a button on the remote control, located in the chest area. The profile allows the glove to flexibly respond to different requirements encountered during the course of a typical workday. For example, if a person performs slightly stressful tasks during the morning followed by activities in the afternoon that place heavy strain on the muscles, the profile accommodates both conditions. This also allows both male and female users to work with one system. Within milliseconds, the system can provide up to 80 N of gripping force. The system is also designed not to impede the wearing of personal protective equipment (PPE), such as gloves, fallprotection devices, helmets or warning clothing. For breaks, it can be put on and taken off without external help. The capacity of the batteries in the power supply is designed for a typical working day.
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MOTION SYSTEM APPLICATIONS Shown here is an exploded cutaway of a slotless motor from Portescap. Notice (in copper) the ironless rotor-coil windings. Also notice the brushes (on flat springs) mounted on the black motor endcap (the rightmost subcomponent in this illustration). Portescap sells this motor with either sleeve or ball bearings for the output shaft support.
Brush DC versus brushless DC motors in disposable tools Disposable medical hand tools are seeing increased use due to their cost and hygiene benefits. Engineers who design these tools usually specify brush DC or brushless DC motors. Here we compare these two options. By Clémence Muron Applications engineer | Portescap
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AN
early step of surgical power tool engineering is to determine whether the design will be disposable or reusable. Recent component design and manufacturing advances have rendered many single-use power tool designs for complex surgery a cost-effective option. Nowhere is this more apparent (or significant) than with today’s brush DC and brushless DC (BLDC) motors both of which have lower price points and higher performance than in the past.
cost requirements are vastly different. Reusable tools must often last hundreds or even thousands of surgeries — so must integrate premium components. In contrast, the components in disposable tools only need to perform for one surgery — which necessitates that these components be available in high volumes and at a competitive price.
Reusable and disposable surgical tools often have equivalent motor-performance requirements. However, their design life and
Though they may be too costly for disposable power tools, BLDC motors offer top reliability — so are the most common motor type in
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BRUSHLESS DC MOTORS FOR REUSABLE TOOLS — BRUSH DC MOTORS FOR SINGLE-USE
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BRUSHLESS & BRUSH DC MOTORS & DRIVES
reusable power tools. Brushless motors are capable of speeds up to 100,000 rpm over a long design life. Contact-free BLDC commutation (usually via magnetic Hall sensors or a sensorless drive with a brushless motor controller) limits all mechanical wear to that of the motor-shaft support bearings … so with precision bearings, these motors can operate at high rpm over (in some cases) hundreds or thousands of surgeries. In contrast, DC-motor brushes (whether graphite or precious metal) physically contact the rotor’s commutators, so wear over time. That means these brushes are the primary limiter of brush DC motor life — with higher speeds accelerating wear. That’s acceptable in disposable tools, even some requiring high rpm … though ultimately the motors’ suitability heavily depends on the tool’s duty cycle and exact speed requirements. Depending on the exact design and materials, brush DC motor performance also varies. For example, certain coreless brush DC motors have lower inertia for higher performance regarding acceleration and efficiency than comparable motors of a different construction. Recall from a previous Design World editorial that most lower-cost brush motors have an iron core … but coreless motors have rotors consisting of only a coil and shaft. Besides the aforementioned benefits, these coreless motors also eliminate detent torque (cogging torque) for smooth rotation even at slow speeds. No wonder brush DC motioncontroltips.com | designworldonline.com
motors of this type are finding increased use in disposable power tools.
Shown here is a cutaway of a Portescap Ultra EC 35ECS slotless brushless motor. The magnet on the rotor (in grey) is precision balanced; the PCB that controls the electronic commutation (green) is embedded inside the motor housing.
MOTOR -POWERED TOOL C OST - ANALYSIS EXAMPLE Once performance requirements are met, cost is often the next-most critical design consideration. We’ve covered how motors with a BLDC construction are relatively expensive … and in fact, the controllers they require (for commutation) and embedded electronics (for tracking rotor position) further increase overall system cost. The additional cost for these subcomponents (along with premium bearings, dynamic shaft seals, or high-grade magnets) can be justified where the application demands top performance … but not usually for disposable tools. In contrast, DC motors with their brushbased commutation only need a cost-effective PWM circuit for speed control … and motor-construction advances have made for unprecedented performance increases with only negligible cost increases. That’s made today’s more advanced brush dc motors particularly suitable for short-life surgical tools. Refer to the charts accompanying this article for average-cost analyses of various tool options. These don’t account for how high-end reusable tools typically offer superior performance and additional capabilities. Such factors may make tools based on BLDC motors the best design choice for surgeons and patients even if a breakeven surgery 11 • 2020
The increasing popularity of disposable surgical power tools (such as surgical staplers) has prompted more demand for higherperformance brush DC motors. These are more suitable than BLDC motors where cost effectiveness is the top design objective.
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quantity isn’t reached. However, the analyses also don’t account for one unpredictable cost of the sterilization process — the potential risk of infection from inadequately sterilized reusable tools. Wellenforced sterilization methods and tool design features can certainly facilitate proper and reliable sterilization, and sterilization has been proven safe and effective. However, inadequate tool sterilization between surgeries is a risk that should also be considered by surgical-tool design engineers. Disposable tools can be sterilized and packaged by the tool OEM, and this approach boosts patient safety for some applications and hospital systems. Case in point: Consider a new design being developed by an R&D team at a medical-device company. This is a handheld surgical power tool that can cause grave complications if it stops working during a procedure. The engineers prefer a disposable tool, but a reusable tool may be acceptable. The battery-powered device requires that the motor be 80% efficient (or better) and run off 6 to 9 V at 1.5 A (maximum). The motor (not to exceed Ø17 mm) must deliver 5 mNm (continuous) at 15,000 rpm. The procedure is cost sensitive, so the motor mustn’t contribute more than $20 to the cost of each surgery. The engineers first engage with a motor supplier offering both brush DC and BLDC motors as well as extensive experience in the surgical power tool market. The supplier suggests motors that are Ø17 mm or smaller and best matching the design’s performance and power requirements: Both motors satisfy the 5 mNm torque requirement, but the maximum continuous torque rating for the DC brush motor is only slightly higher at 5.7 mNm. This reduces motor life — though not enough to be a concern for a single surgical
With disposable tools, cost incurred for a single surgery includes the full purchase price of the tool. With reusable surgical tools, a small portion of the purchase price is amortized for each procedure … although the cost of re-sterilizing these power tools incurs additional cost that should be considered in per-surgery cost assessments.
A costlier reusable tool (perhaps using a higher performing BLDC motor instead of a low-cost brush DC) will necessitate uses in more surgeries to be less expensive than a disposable tool. Sterilization costs also increase the number of procedures needed to break even — so much so that disposable tools are in some cases preferable no matter the number of surgeries.
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MOTION SYSTEM APPLICATIONS The application dictates which motor technology is most suitable. Engineers designing surgical devices can do well by collaborating early in the design process with suppliers offering surgical-design expertise and a variety of BLDC and brush DC motors.
BRUSHLESS MOTORS IN ROBOT WHE E L S ElectroCraft Inc. now offers an MPW wheel drive built around a high-torque-density brushless dc motor with a heavy-duty integrated planetary gearbox. These motion components mount inside the hub of a lightweight aluminum wheel with custom tread. Designed for mobile robot applications, the MPW combines performance with high efficiency, quiet operation, and long life. The MPW52 (150-mm wheel) delivers up to 12.4 Nm at 2.4 m/sec while carrying up to 68 kg per wheel. The MPW86 (200-mm wheel) provides a peak torque to 35 Nm at 1.9 m/sec while carrying up to 227 kg per wheel. The MPW provides a complete motorized wheel-drive solution for mobile platform OEMs, eliminating the need for robot builders to design a solution using disparate components from different suppliers. The ElectroCraft MPW is engineered for integrated efficiency ... as the motor, gearing, hub, wheel assembly, and optional accessories provide a single-source solution for efficient battery-powered AGV and mobile-robot applications.
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BRUSH DC MOTOR
BRUSHLESS MOTOR
Package
Ø 17mm • 26 mm long
Ø 13mm • 47mm long
Max continuous torque (mNm)
5.7 mNm
9 mNm
Max recommended speed (rpm)
10,000 rpm
100,000 rpm
Controller
PWM
BLDC controller with Hall sensors
Voltage required
7V
9V
Current draw
1.4 A
1.2A
Output power
9.8 W
10.8 W
Efficiency at working point
80%
72%
Example price
$15
$160
procedure. The bigger problem is the 15,000 rpm speed requirement, which is higher than the brush DC motor’s top speed. Though possibly acceptable for a single procedure, it increases the risk of failure during surgery. The cost of the motor is low enough that it can be thrown away after each use. The BLDC motor can easily meet the speed and torque requirements and could continue to do so for many surgeries. Efficiency doesn’t quite meet the 80% target, and the price is much higher than $20 … so for the BLDC motor to be viable, it’d require use in at least eight surgeries. In short, the design constraints force the design engineers to choose between a brush DC-motor-based disposable tool or a BLDC-motor-based reusable model. A reusable brush DC motor isn’t viable (because of the unacceptable risk of failure if used in more than one surgery) and cost precludes a disposable BLDC motor model. The top design question then becomes: Is the potential failure of a brush DC motor in its first surgery (due to high rpm) acceptable? If not, then engineers can reduce the speed requirement — and build lowerperformance tool. The other option is to build the reusable tool and accept its lower efficiency. They will also have to design the rest of the tool to be sterilizable and will need their end users to sterilize the tool between uses — two factors that increase the total cost per surgery.
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STAGES • GANTRIES • HEXAPOD PLATFORMS
The new DXOMARK Analyzer is a measurement system for quantifying the still and video image quality output by devices under testing.
The H-840 hexapod is designed for testing image stabilization systems and is certified to CIPA Standard DC-011-2015. | courtesy of DXOMARK
Hexapods precisely jostle cameras during image-stabilization testing The six-axis parallel-kinematics systems known as hexapods excel in motion simulation and testing of mechanical and drive systems, multidimensional position sensors, and (the focus of this article) imagestabilization designs for cameras and video equipment. By Doris Knauer • Project Manager Industrial Automation | Physik Instrumente (PI)
motioncontroltips.com | designworldonline.com
MODERN
camera systems are capable of astounding feats, including:
• Capturing sharp pictures in fast-changing ambient conditions • Taking snapshots of moving scenes sans blurring • In surveillance systems, identifying dangerous situations • In automotive driver-assist systems, recognizing traffic signs and road marks To help quantify the quality of still and video images and fairly compare competitive imaging devices from different suppliers, some testing equipment uses hexapods to simulate the movements to which cameras are subject during operation. That’s of keen interest to end users such as smartphone and camera manufacturers and those in the automobile and aerospace industries (as well as the security and automation technology sectors) wanting to maximize the quality of the stills and video images their products generate. Of top interest are comprehensive tests that measure devices’ outputimage resolution, contrast, color, texture, zoom, and exposure — as well as their autofocus and image-stabilization capabilities. A typical test collects and analyzes thousands of images for statistically significant results of all attributes.
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Driver-assistance systems also rely on high quality images. | courtesy of PI
The challenge is that image-quality test results are only comparable when cameras and camera components are tested under consistent conditions and methods. Consider DXOMARK, a French camera and video-device laboratory and testing company for manufacturers of DSLR and DSC products, smartphones, video-based driver assistance systems, and devices for
surveillance, aerospace, defense, and machinevision applications. DXOMARK offers serves for the analysis, comparison, and optimization of image quality. The company’s Analyzer system consists of hardware, software, and extensive testing protocols bundled within several modules for repeatable operator-independent results. Different modules can be used and combined depending on the task at hand or on
the image quality attributes under evaluation. A unique Analyzer capability (a visual noise measurement) quantifies visual noise metrics directly correlated with visual perception. Video analysis encompasses exposure, white balance, definition and texture for changing lighting conditions; automated lighting scenarios can also be programmed for userspecific test requirements. The latest version of
Precision Motion Sub-Systems
For Photonics Alignment, Laser Processing, 3D Printing PI provides precision mo�on and automa�on sub-systems based on: Air Bearings and/or Mechanical Bearings Standard and Custom Gantries EtherCat®-based Mo�on Controllers Cartesian Robots and Hexapods Linear Motors, Voice Coil, Piezo Drives
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PIFOC® high-speed nanofocusing drive, <1nm resolu�on
So�ware support for laser processing and 3D prin�ng allows direct import of industry standard STL files
PI is a privately held company that designs and manufactures world-class precision mo�on and automa�on systems including air bearings, hexapods, and piezo drives at loca�ons in North America, Europe, and Asia. The company was founded 5 decades ago and today employs more than 1300 people worldwide. PI’s customers are leaders in high-tech industries and research ins�tutes in fields such as photonics, life-sciences, semiconductors, and aerospace.
DESIGN WORLD — MOTION
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ENABLING INNOVATION SINCE 1970
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STAGES • GANTRIES • HEXAPOD PLATFORMS
Analyzer includes the Selfie module to enable accurate and repeatable testing of smartphone front cameras. The measurement methods for the DXOMARK evaluation have been developed in collaboration with several companies that contribute to international standardization working groups such as IEEE/CPIQ and ISO TC42-WG18. The image stabilization test assesses how well a camera’s built-in optical and electronic image stabilization systems work. These systems work to compensate for device movements to prevent blurring of captured images. For example, sensors measure linear and angular motion accelerations, such as a photographer’s shaky hands or the vibrations of vehicles and aircrafts, so that the system can automatically offset these influences and avoid blurred images. The effectiveness of image stabilization systems (whether optical or electronic) is assessed using a Camera and Imaging Product Association (CIPA) protocol established by Japanese camera manufacturers for defining motion-simulation test conditions. Motion simulation with high repeatability: All image-stabilization test methods demand reproducible camera shaking of a camera and vehicles and aircrafts vibrating. “We must ensure that the simulated frequencies and movements such as those around the rotation axes (θX, θY, θZ — pitch, yaw, roll) are identical for each test,” says Nicolas Touchard of DXOMARK. “We currently use hexapods in the latest version of Analyzer, because they deliver precisely reproducible motions up to 30 Hz for many potential test scenarios.” Camera and smartphone tests typically
require up to 12 Hz … but the image stabilization functions of driver-assistance systems require much higher frequencies. Thanks to their parallel-kinematic design, hexapods excel in such precise motion and vibration simulation applications. They outperform serial (stacked) systems in such testing with better path accuracy, repeatability, and flatness. In addition, the moved mass is lower for better dynamic performance … which is the same for all motion axes. Moreover, cable management is no longer an issue, because no cables move on the platform. Plus the system has a much more compact design. Suitable specifications and qualified support: The hexapods used in the latest version of Analyzer are from the German precision positioning-technology company Physik Instrumente (PI). Case in point: The PI H840 hexapod (certified to CIPA Standard DC011-2015) allows testing of image-stabilization systems. The CIPA standard defines rotational axes, test frequencies, and vibration amplitudes. Since mid-2019, another hexapod is being used in the Analyzer. The H860 hexapod is designed specifically for testing image stabilization systems. It offers simulation frequencies up to 30 Hz, and travels predefined trajectories, sinusoids or freely definable paths with a high degree of trajectory control. Due to its friction-free voice coil drives and lightweight design — consisting of extremely stiff carbon fiber parts with low moving masses — it can achieve fast and smooth motion, as well as high acceleration. The hexapod is fixed to a base plate with brackets to keep the test device safely in place
Hexapods are used to simulate the movement the cameras are subjected to while taking pictures. | courtesy of PI
This is a C-887 digital controller from PI to allow easy control over hexapods — specified in Cartesian coordinates. The controller automatically makes the transformations for the hexapod’s six individual drives.
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ng es ch motioncontroltips.com | designworldonline.com
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during vibration simulation. “We chose these hexapods for vibration simulation and because PI provides qualified support — for example, in the form of software-driver adaptations,” adds Touchard. Easy control and a freely definable pivot point: The high-performance C-887 digital controller handles control over the hexapods and (with user-friendly software) enables easy configuration. Positions are specified in Cartesian coordinates, and the controller calculates the transformations to command the six individual drives. The hexapod’s freely definable rotation or pivot point is an essential feature that lets the hexapod platform adapt to the position of the camera’s image stabilization component — so the image sensor can be located in the middle of all six degrees of freedom, for example. Another application of hexapods is in the calibration of gyroscopic compasses (according to DIN ISO 22090-1) for shipping and marine technologies.
The PI H-860 hexapod (with direct drives on each axis) can simulate vibrations to 30 Hz as well as predefined travel trajectories, sinusoidal motions, and other freely definable paths. | courtesy of DXOMARK
“We must ensure that the simulated motion remains unchanged for all tests. Hexapods are very well suited to this task,” says Nicolas Touchard of DXOMARK.
Smartphone end users want their snapshots to be sharp regardless of ambient conditions. | courtesy of PI
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MOTION SYSTEM APPLICATIONS
Sensors aid packaging machine flexibility SENSORS
have always been the unseen elements that make complex machines perform at their optimal level. This is true for all kinds of machines, including the latest generation of packaging machines.
now the successor model AP05. They are compact, easy to integrate into the machine control system and very user-friendly in terms of readability and clarity.” Adjustments on SOMIC customer machines are different: “There are machines with only one format setting, socalled Highrunner lines. Other customers, on the other hand, have up to 20 or 30 formats on the lines and make full use of the flexibility.
Companies that need to invest in packaging machines value flexibility where a single machine can handle a wide range of package sizes and formats. This requirement is often met with intelligent size changeover. An example comes from the SIKO electronic position indicators used to simplify the changeover process on SOMIC packaging machines. SOMIC is well known for innovative solutions in end-of-line packaging machines — for secondary and tertiary packaging. These include wraparound packers, tray packers or tray lid packers as well as machines for display packaging presented to customers in the supermarket. Here, either the wraparound carton has a typical tear perforation or, in the tray lid version, the lid is removed and the product is presented in the tray. SOMIC machines are characterized primarily by the fact that the respective carton is folded around the product in its primary packaging and not inserted into a pre-folded carton via picker, as is the case with other machines. SIKO mechanical position indicators are installed in all SOMIC machines for possible size changeovers to different product or packaging sizes. “We have already enjoyed many years of good cooperation with SIKO in The SOMIC 424 DT Lid-tray packer collects, the field of mechanical position indicators”, groups and packages products in open cartons says Dr. Johann Härtl, Head of Construction or in lid-tray packs with the lid inside. at SOMIC. “For about nine years now, we | courtesy of SOMIC have also been using the electronic, buscompatible SIKO displays, first the AP04 and
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SENSORS
Some even produce wraparound and tray packaging on a single machine, where a wide variety of products need to be packaged. SOMIC covers a large product range in the food sector, but also in non-food, pharmaceuticals and cosmetics.”
PROCESS RELIABILIT Y WITH RED/GREEN SYSTEM The integration of the electronic SIKO position indicators offer a number of advantages of monitored size changeover including faster changeover times, ergonomic operation and high process reliability. The operator selects the respective format, which is stored as a recipe in the machine control system, and the The SIKO AP05 position indicator with system sends the new set values to the displays to be green status LEDs shows a correct machine adjusted. The backlit LCD displays are easy to read setting. | courtesy of SOMIC and also feature green and red status LEDs. When the correct value is reached by turning a crank, the LED changes to green: Position reached. Otherwise the LED will continue to light up red and readjustment is necessary. Arrows also conveniently indicate the direction in which adjustment is required. As the communication interface of the SIKO position indicators in the machine control always provides the current position information, it effectively rules out incorrect settings which could lead to quality problems or even damage to machine parts upon restarting. Adjustment with electronic displays is much more efficient, especially on machines with many adjustment points and frequent changes. The machine stores all default values so that target positions no longer have to be manually selected from format lists. With SOMIC, the factors of time savings and efficiency are not only guaranteed by electronic SIKO position indicators when changing formats, but also by the “Quick Change Principle”. Here, format parts are changed in their entirety in the machine. All that’s needed is a quick-release fastener, which means that no further tools are required. Taken together (adjustment via electronic position indicator and Quick Change principle), SOMIC packaging machines can be converted to new dimensions much more efficiently. As Dr. Härtl points out, “The AP05 is optional; mechanical SIKO meters are installed as standard. However, the trend is 2,200-2,400 psi clearly moving towards electronically monitored indicators, especially since around 90 to 95 percent of our machines require size changeovers.” Approximately 50 percent of the company’s -100°F to +400°F customers already use the electronic version, with SOMIC expecting a further increase. Härtl adds that “The digitalization of machines continues to increase. And the AP05 is one more sensor that helps record machine data.” 75-85 Shore D
Supreme 11HT-3A
HIGH STRENGTH ADHESIVE
Tensile lap shear strength, 75°F Service temperature range Hardness, 75°F
Hackensack NJ, 07601 USA ∙ +1.201.343.8983 ∙ main@masterbond.com DESIGN WORLD — MOTION
57
www.masterbond.com
MOTION SYSTEM APPLICATIONS
Industrial gas springs help in fight against COVID-19 GAS
springs, also called gas dampers, tension springs, gas-pressure springs depending on the setup and context, are compressed-air or oil cylinders that install in motion designs to damp forces and return kinematic linkages and more complicated assemblies to default positions. Gas springs work through a piston on the end of a rod that protrudes from a steel cylinder body; usually compressed gas (often nitrogen) within the cylinder exerts force on this piston to reassume and maintain set positions. Nitrogen is common here because it’s inert and nonflammable. In such designs, oil or grease between the piston and other contacting parts minimize friction. In fact, the small amount of oil in these gas springs serves another function — to further damp and gently decelerate gas springs during full extension or compression. Some setups even include a fine hole in the piston for damping that’s still slower than with other designs; such slow-damper springs are common on safety gates and doors. In contrast, extended-reach gas springs usually leverage telescoping mechanisms pairing multiple cylinders on one rod; then the smaller cylinder extends from within the larger cylinder. Consider one particularly long-stroke application: Passive heave compensators — systems on ships or offshore oil-rig systems that reduce the effect of waves on engineered structures — use gas springs with strokes to many meters long. Still other gas-spring applications include those for medical beds and hoists; industrial equipment such as machine-tool presses; off-highway and automotive equipment for hatches, hoods, and covers; office equipment and furniture; and general strut and support applications. Fast-acting gas springs find use in weaponry and aerospace design.
This is an ACE Controls pull-type gas spring.
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SHOCKS • DAMPING • GAS SPRINGS
FORCE, N
GAS-SPRING FORCES AND STROKES
F₃
G A S -S
E XT E N S P R IN G G A S -S
F₁
F₄
IO N
COMPR P R IN G
E S S IO N
with ACE Motion & Vibration Control Products
F₂
STROKE, MM F1 (and F₂) = Extension forces with extended (compressed) piston rod F₃ (and F₄) = Pull-in force with extended (compressed) piston rod
Specific variations include gas springs with standard or fixed-height cylinders; spindle-only designs; and cable, return, adjustable auto-return, nonrotating, stage, and multi-mode cylinders. No matter the iteration, gas-spring extension force — a value that usually ranges from 1 to 5,000 N — depends on piston-rod crosssection multiplied by fill pressure. Manufacturers commonly express extension force with two values — for rod extension and rod retraction — at normal ambient temperature and with the piston rod pointing downward. (Note that typical ranges are only those most common; some gas-
Buy a Solution Fast
Gas springs come in push-type and pull-type variations. For tension springs the compression (retraction) is the extension position, and vice versa. The difference between extension and compression forces for a give rod position is equal to the gas spring’s friction force.
Industrial shock absorbers Industrial gas springs Vibration isolation
Standard products available to buy online Tools Sizing & specification ▪ Online calculations & product selection
▪ One-on-one
application assistance
Resources Online & downloadable ▪ ACE CAD database ▪ ACETips video tutorials ▪ Technical blog &
This is Wandong’s mobile X-ray machine.
11 • 2020
case studies
DESIGN WORLD — MOTION
59
800-521-3320 www.acecontrols.com
MOTION SYSTEM APPLICATIONS
The ACE Controls’ GS-28-450 pull-type gas spring provided a 270-lb traction force and low progression rate to hold the mobile X-ray beam arm in position and support raising and lowering motion.
PROVEN SHOCK, VIBRATION & NOISE REDUCING SOLUTIONS
MATE
RIAL
STANDARD PRODUCTS GUIDE OVER 600 PARTS 800.838.3906
sorbothane.com
spring applications in heavy industries use gas springs delivering several hundred-thousand Newtons.) Other gas-spring definitions include two pull-in forces — at rod extension and rod retraction — and overall friction force. These values depend on the gas spring’s gas and damping-oil volumes. Various nozzle orifices and oil quantity allow control of push-out and push-in speed. Consider one example application of gas springs: As Wuhan, China became the first metropolis to confront COVID-19, crisis managers relied on mobile X-ray machines to quickly supply intensive-care physicians with imaging of patients’ lungs. Medicalimaging machine builder Beijing Wandong Medical Technology Co. supplied these machines. The mobile X-ray machine has a beam arm that’s adjustable to patient anatomy. The arm in turn uses a gas spring to hold its position without dropping on technologists or patients. When COVID-19 struck, Beijing Wandong suddenly needed a large quantity of springs to complete a rush order of the X-ray machines … so they turned to ACE Controls. The mobile X-ray machine is 66.1 lb including its 22-lb beam arm. So in addition to the total weight, ACE Controls engineers had to account for the starting point (0°) and opening angle (130°) when choosing the specific gas spring. Ultimately the engineering team chose GZ-28-450 pull-type gas springs — part of the component maker’s industrial gas-spring family. GZ-28-450 gas springs have a 1.10-in. OD, maximum force to 2,700 lb, at a stroke length of 17.72 in. — making them suitable for the mobile X-ray unit’s requirements. The gas springs reliably hold the beam arm in position and provide assistance when imaging technologists raise and lower the arm … in contrast with push-type gas springs. More specifically, the gas pressure in the cylinder draws the piston rod in and supports the manual force needed for controlled motion when moving the arm. No matter the stroke length, the GZ-28-450’s traction force is adjustable thanks to a built-in relief valve. Ultimately, ACE Controls industrial gas springs boost the safety and user-friendliness of Wandong mobile X-ray units.
SORBOTHANE® MADE IN THE U.S.A.
60 Sorbothane_DesignWorldAd_8-2020_B.indd 1
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DESIGN WORLD — MOTION
MOTION SYSTEM APPLICATIONS
Retaining rings keep assemblies together MOTION
system designs make use of retaining rings in everything from electric motors and gear retainers to solenoids to aircraft to door handles and sports equipment. These fasteners hold together components on a shaft or in a housing when installed in a groove. In fact, the automotive industry may make the most use of retaining rings, especially for assemblies in air bags, timing-belt pulleys, radiator hoses, turbo chargers, door locks, carburetor assemblies, drive shafts, and brakes. Used in an array of oil-and-gas and other industries’ designs, tapered section rings have decreasing thickness from center to ends. They mount axially or radially, and the taper keeps full contact with the installation groove. Common in assemblies for lawn mowers, hand and power tools, agricultural machinery, nuclear equipment, and even computer equipment, constant-section retaining rings have a constant width around the circumference of the ring. When installed, these rings do not maintain uniform contact with the entire component. They take on an elliptical shape and make contact with the groove at three points. Spiral retaining rings go into housings or on shafts with full contact with groove or component. Their grooves are shallow, so have less load bearing capability. So, spiral rings often go into applications that prioritize full contact with the retained component or lower axial profile. Spiral rings find use in torque converters, speed reducers, lamp assemblies, clutches, hinge pins, home appliances, robotic toys, pumps, couplings, valves, hydraulic equipment, and photography equipment. They don’t have protruding ears to interfere with mating components; they also eliminate the need for machining and threading. Spiral retaining rings don’t necessitate special tools for removal and come standard with removal notches for extraction. When selecting a retaining ring for an application, factors that dictate which retaining ring is most suitable include application environment (including temperature, speed, and thrust) as well as critical dimensions (including the assembly’s housing or shaft diameter and the installation groove’s dimensions. In fact, maximum thrust is one of the most critical application parameters, as it dictates whether there’s risk of groove deformation or ring shear. Applications that run in corrosive environments also may also need retaining rings made of specialty material.
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MAXITORQ AHA25 clutches and brakes from Carlyle Johnson are rated from 15 lb-ft dynamic to 60 lb-ft of static torque ... and torque can be regulated by adjusting system pressures. These components have a stationary cylinder assembly mounted on deep-groove ball bearings to accommodate thrust loads. Notice the retaining ring on the face of the unit.
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25,000+
Catalog Springs
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Custom Springs
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Visit the All-New Lee Spring Website Easily find the right spring every time. View multiple spring features, specifications, pricing and quantity breaks side by side for easy spring selection. Call: 888-SPRINGS (888-777-4647) Visit: leespring.com Fax: 888-426-6655 Email: sales@leespring.com
AD INDEX MOTION SYSTEM APPLICATIONS
ACE Controls ................................................................... 59 AllMotion........................................................................... 2 Bansbach Easylift ............................................................. 61 Beckhoff Automation ...................................................... 55 Bosch Rexroth US ............................................................ 25 C-Flex .............................................................................. 17 CGI Inc............................................................................. 41 Del-tron Precision Inc. ....................................................... 7 Diequa ............................................................................. 39 Digi-Key ........................................................................... 19 Elliott Manufacturing ......................................................... 4 Emerson Machine Automation Solutions ....................... BC Encoder Products Company ........................................... 33 Fabco-Air, Inc. ................................................................. 21 FAULHABER MICROMO ......................................Cover, 43 Festo................................................................................ 23 Fluid Line Products .......................................................... 15 Harmonic Drive ............................................................... 37
Intech............................................................................... 38 Lee Spring Company ....................................................... 63 Mach III ............................................................................ 14 Master Bond .................................................................... 57 maxon .............................................................................. 49 mk North America, Inc. ................................................... 28 Ogura Industrial .............................................................. 13 Parvalux ......................................................................... IBC PBC Linear ......................................................................... 9 PI (Physik Instrumente) LP ............................................... 52 POSITAL FRABA .............................................................. 34 Pyramid Inc. ..................................................................... 27 R+W America .................................................................. 31 SEW Eurodrive .................................................................. 1 Sorbothane ...................................................................... 60 THK America, Inc............................................................... 3 Zero-Max, Inc. ................................................................IFC
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Scalable Motion Solutions for Your High Performance Applications Emerson’s new PACMotion™ portfolio enables you to scale your motion capabilities without sacrificing performance. Our new family of servo motors, servo drives, software and motion controller easily integrates with our PACSystems portfolio for a complete solution for high-speed, high-precision processes in packaging, printing, material handling, semiconductors, food and beverage and manufacturing or other applications where a high number of axes are needed. Emerson offers end-to-end automation solutions for your high-performance machinery applications. Visit www.emerson.com/PACMotion to learn more. Reach out to us directly at ContactUs@Emerson.com
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