Effective material removal using lasers

Lasers are used in a variety of applications in the field of material removal, with a range of machines suited to each process distributed by Raymax Applications in Australia.

Laser systems offer two general processes for material removal. One widely used process occurs during manufacturing for the production of new products that require micromachining. The other refers to a removal of surface congestion or contamination in a large industrial environment. For either process, the team at Raymax are able to provide expert advice, installation and on-going support. Precision material removal in the production of medical products can be carried out with an excimer laser produced by the OPTEC/ LASEA Group, a Belgium-based company that works with some of the largest medical manufacturers in Europe. OPTEC excimer lasers are used to manufacture components for electrophysiology (EP) because they can strip or ablate wire as thin as a human hair. Nitinol wire, an amalgam of nickel and titanium that is highly elastic with excellent shape memory, is initially manufactured with a transparent plastic coating. A suitable laser is used in the micro-machining process to cut away the insulative coverage without damaging the nitinol wire. In procedures for cariology or neurology, the recipient organ is accessed using a nitinol guidewire via the vascular system to insert a catheter to clear the blockage and then insert a stent. Stents are also made with nitinol wire after the ablation or material removal process. A second micro-machining material removal application using highprecision lasers is laser ablation of thin layers. This is particularly useful with semiconductor devices that continue to ‘shrink’ in size. Through the combination of the latest generation of femtosecond lasers and ultraprecise scanners with a high dynamic range, excellent quality and rapid ablation are achieved with no spatter. LASEA lasers can ablate material over a narrow thickness and in a highly localised and selective way. Called ‘decoating’, it occurs by vaporising or subliming a layer without damaging the underlying layer. Controlling the energy is critical to this process, so as not to damage the substrate at all, and where thicknesses vary, to optimise the energy per pulse to lessen the impact. This process improves the quality and the rate of production in fields such as solar cell production, OLEDs and microelectronics. Precision material removal can be applied to other sectors including vehicle manufacturing by ablating the metal layer covering windscreens to access electronic sensors; and in the jewellery sector – lasers can ablate the thin layer on a watch face ready for chemical etching, and even create internal or external patterns or designs on containers used in the cosmetic industry by ablating the glass. An industrial application that has recently been tested and confirmed is the use of blue diode lasers for the removal of biofouling on ship hulls and other metal sub-sea structures. This new use of a blue diode laser has only become possible due to advances in conversion efficiency and optical output power developed by the German laser company Laserline. Commenced in 2019 and funded by the German government, the research project FoulLas – ‘Fouling removal of maritime surfaces using laser radiation underwater’ – was undertaken on the North Sea island of Helgoland, to find a more environmentally-friendly process than the toxic effects of biocide coatings applied to ship hulls. A solution is timely, as restrictions on the use of biocide coatings have increased. Operators of ships and offshore facilities are doing all they can to get rid of these unwanted organisms or to ensure they do not settle in the first place. Currently used as a preventive measure, biocidal antifouling coatings have been applied either to prevent the growth of vegetation or to destroy the cell structures of adhering organisms. However, due to their toxic effect on other aquatic organisms, only a few biocides have been approved, and even these will completely be banned in the foreseeable future. One biocide-free alternative is in silicone-based antifouling coatings that create a particularly smooth surface structure. An alternative

Production of the LDMblue highpower diode laser at Laserline.

Partial ablation of the clear plastic coating on a thin (Nitinol) wire.

removal method is mechanical cleaning by diving teams, which is expensive and time-consuming. Mechanical cleaning by diving crews releases numerous marine organisms, which then migrate unwantedly into the local ecosystems; as a result, mechanical ship cleaning has been banned in many ports. Experience shows that these measures have only had limited success, coatings appear to simply delay colonisation. Organisms colonise quickly and in large quantities, so that even when coatings are used, a considerable amount of new biofouling growth occurs within a very short time. Additionally, marine organisms have developed highly effective strategies for adhering to surfaces – their attachment is almost as robust as industrial adhesive bindings. To find a better removal solution for this unwanted material and prevent further growth of aquatic organisms, the FoulLas research team applied an effective process using the more powerful diode laser sources of the blue spectral range developed by Laserline. With more than 2kW of blue laser power, an underwater irradiation technique was used to damage the cell structures of marine organisms that had settled on a ships’ hull. Once damaged, the marine growth matter is washed away by the current, resulting in a far more eco-sensitive process. Today it is possible to apply lasers for material removal across a range of manufacturing processes and in product maintenance. Precision material removal using micro-processing has already been adopted by both the medical sector and the electronics industry. The high power of blue diode lasers has been proven an indispensable tool for maintenance of sub-sea structures and the hulls of ships. These examples show just how effective laser systems can be in everyday usage for material removal. www.raymax.com.au

Vollmer launches new VGrind 360S

At the EMO machine tool exhibition in Milan last October, Vollmer delivered the exhibition premiere of its new VGrind 360S grinding machine, for the complete machining of carbide tools.

Designed to set a new standard for the complete machining of rotationally symmetric solid carbide tools, the new VGrind 360S offers an impressive solution for manufacturing cutting tools for aerospace, medical, automotive and general subcontract manufacturing sectors. This new five-axis CNC grinding machine can be used productively to machine carbide tools with a diameter up to 25.4mm. Depending on the machine kinematics and the equipping of the grinding wheel packages, it can even be used for tools up to 150mm diameter. The VGrind 360S incorporates wear-free linear induction motors on the X, Y and Z-axes to lower maintenance costs for the machine while demonstrating higher surface quality for the tool and improved precision. The tried-and-tested vertical double-spindle concept from Vollmer now features an oriented spindle-stop for the first time. Also known as spindle indexing, this always stops the spindle at a specific position; the result is a reduction of axial run-out errors and concentricity issues, while offsetting wear in the HSK holding system. Another new feature is a heat plate exchanger to efficiently cool motors and spindles, which in turn leads to increased thermal stability. Furthermore, this effective cooling concept has now been optimised and extended, making it the ideal solution when processing tools to the tightest of tolerances. Simple and intuitive operation is at the core of the VGrind 360S. For customers to fully exploit its potential, Vollmer has created an ergonomic platform whereby users can operate the control panel comfortably while having full visibility of the work envelope. Operation via the keyboard or touchscreen allows for precise machining of the tool, and the multi-function handwheel ensures even more flexibility as it can be freely positioned on the enclosure. This design allows the setting of a required axis without using the control panel. The VGrind 360S incorporates Vollmer’s trusted operating concept and can be operated unmanned around the clock thanks to automation features such as a pallet magazine, free-arm robot or chain magazine. The options for automation include the HP 160 pallet magazine for up to 900 tools with a double gripper to guarantee fast changeovers, the HPR 250 free-arm robot for the automatic machining of tools with various shaft diameters, and the HC 4 chain magazine, which has space for 39 HSK-63A tools or up to 158 shank-type tools. This automation also extends to the eighttool grinding wheel changer that ensures you always supply the right grinding wheel for the job at hand with no manual intervention. As an option, coolant nozzles can be automatically exchanged with the wheel sets on both spindles. From an options perspective, Vollmer has sought to deliver maximum productivity and performance. The optional features include the flexible loading automation options for carbide tools, grinding spindles available with direct or belt drive, automatic gripper compensation as an in-process solution, wheel compensation probes, automated changing of intermediate sleeves with bayonet, and an automatic stacking unit that enables the abrasive grinding wheel to be opened during the grinding process. Other available features include the simultaneous grinding wheel package and tool change in combination with the HP 160 pallet magazine or the HC 4 to reduce non-productive times during loading and a stable, fully adjustable steady rest with automatic stroke to prevent deflection and ensure optimal grinding results. www.vollmer-group.com