Delcam's PowerMILL CAM system is being used by Oxford Lasers to program the company's range of laser-based micromachining systems. After many years' success with three-axis systems, Oxford Lasers is now producing five-axis equipment.
Dr. Dimitris Karnakis, Project Leader responsible for micromachining systems and applications at Oxford Lasers, believes that micromachining with lasers on a very small scale, offers distinct advantages over conventional machining technology. He believes that, comparatively, lasers can machine very quickly, more accurately and give a better surface finish, without the challenge of producing cutting tools that are both small enough and robust enough to cut shapes at the micron level. Similarly, he claims that lasers can produce the smallest shapes more effectively than using EDM.
Oxford Lasers was founded following pioneering laser research at Oxford University. Over the past 30 years, it has become established as one of the world's leading laser manufacturers. During that time, the company has focussed on two application areas; laser micromachining and high-speed imaging. The company is a world leader in using lasers for micro-drilling, which is used, for example, to form high-precision fuel injectors for automotive engines. It also runs its own manufacturing operation using its own lasers, mainly to demonstrate and prototype the systems to potential buyers. More recently, the company has moved into laser micro-milling.
When milling using a laser, the programming in the x and y directions is the same as a normal milling machine, but a lens moves in z to determine the width of the beam and, therefore, the position and depth of the cut. The depth of cut is also a function of the power of the laser and the material being processed.
Following success with its three-axis equipment, Oxford Lasers has moved into five-axis operation, with the extra axes produced by tilting and rotating the part. This approach allows optimisation of the Ra surface roughness achieving values well below one micron (μm) by running different passes of the laser over the surface at different angles. It also enables undercuts to be created. This is generally accepted to be difficult with lasers because a laser on a three-axis machine cannot cut a truly vertical wall because of the inherent angle in the beam.
"We had problems with our existing software as soon as we tried to move to five-axis operation,'' remembered Dr. Karnakis. "Our customer suggested that we should contact Delcam and we have never looked back. We have been very satisfied, not just with the software but also with the supporting services, especially the knowledge and timely response of the staff on the help desk.''
Several of the five-axis applications stem currently from university research departments. For example, a team at Aston University in Birmingham is using a system from Oxford Lasers programmed with PowerMILL to machine very narrow, high-aspect-ratio cavities into 125 micron-diameter optical fibres to allow manufacturing of fully-integrated in-line photonic devices for real-time sensing. Such in-line devices will be available from FiberLogix Ltd.
Machining these cavities using lasers offers a more flexible, precise and fast method compared to lengthy mechanical polishing methods and without the risk of permanent mechanical failure. PowerMILL enables the production of complex 3D structures on a scale of a few microns, adding a new dimension to the design of photonic devices. It has now become possible to manufacture an entirely new family of devices with many applications over a wide area.
In another example, PowerMILL is used to laser machine microfluidic devices for biochemical analysis. These will allow biomedical researchers to manipulate fluids in networks of channels and monitor reactions requiring only small volume of samples and reagents, producing little waste and offering rapid analysis times at relatively low cost.
Delcam's PowerMILL