MOTION SYSTEM TRENDS
New technologies and applications for linear motors D
epending on the exact technology, typical linear motors can deliver unlimited strokes and (with feedback) accuracies to ±1 μm/100 mm. Speeds range from inches to 1,000s of inches per second. Semiconductor manufacture and assembly as well as machine-tool applications continue to account for the majority of linear-motor applications. However, increased focus on efficiency is spurring new applications for linear motors on axes in packaging, material handling, automotive, off-highway, and general automation. That’s because the direct-drive nature of linear motors makes for top efficiency from linear motors (thanks to negligible mechanical losses) as well as fast and precise (or slow and extremely steady) strokes. So in recent interviews, we asked industry experts where exactly linear motors replacing other linear-motion technologies — and other questions about new technologies aimed at further boosting the performance of linear-motor designs. Here’s what they had to say. William Fang | Engineer • Chieftek Precision USA: Linear motors have far longer life than mechanical linear actuators in short-stroke applications, because they’re not susceptible to wear, shock, and fatigue issues. Linear motors also excel on long-stroke axes. Just consider magnetic-levitation trains, which are essentially linear-motor applications having stroke lengths of many miles. Much the same way, precision linear motors for industrial applications have essentially unlimited stroke lengths. That’s in contrast with most rotary-to-linear-based designs used in motion-
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DESIGN WORLD — MOTION
04b Motors - Linear — Motion Control Trends V4 03.19.indd 48
3 • 2019
This is Chieftek Precision’s ultra-small single-axis TC1-D dc driver. It can drive linear and rotary permanent-magnet synchronous motors (PMSMs). One key strength is its ability to accept various types of digital, analog, and absolute encoder feedback.
control applications such as leadscrews, which have speed limits due to their tendency to whip or thrash beyond a given value. So linear motors are increasingly applied on long-stoke axes where such screws or rack-and-pinion sets might get used despite limitations — on robotic seventh-axis systems, for example. Here, linear-motor designs can be built and installed in 1-m sections – a level of modularity impossible with leadscrews. In one recent installation, a 16-m-long robotic seventh axis based on one long linear-motor installation automates a large assembly area of an LCD production facility. This makes for reduced wiring and (where linear-motor axes move batterypowered tools) no exposed cables or cable carriers at all. DO YOU OFFER DESIGN ENGINEERS ANY VALUEADDED SERVICES? DO THESE INTEGRATORS DESIGN THE MECHANICAL BUILD (INCLUDING THE GEARMOTORS OR LINEAR MOTORS) OR THE SETUP OF CONTROLS AND NETWORKING? motioncontroltips.com | designworldonline.com
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