Big ideas in microfabrication tooling

Fans of Western movies no doubt have vivid memories of watching the cavalry ride to the rescue of someone caught in a difficult situation.

For today’s micromolders, an equivalent could be the moment when the National Research Council’s Industrial Materials Institute (NRC-IMI-London), based in London, Ont., lends a hand with microfabrication tooling.

There is a growing demand for high-tolerance microparts for use in automotive, electronic, microfluidic and biomedical applications. Molders identify micro-EDM (electric discharge machining), micromilling and laser micromachining as the best methods for making the all-important micromolds even smaller in the future — and NRC-IMI-London is involved in all three processes.

Working both alone and in collaboration with other partners, the federally funded organization has developed several micromachining technologies that provide a cost-effective alternative to silicone-based surface micromachining techniques for prototyping applications and small batch production. “Our goal is to apply microfabracation technology to produce microfeatures on molds to allow companies to gain new capabilities for less expense,” said Dr. Evgueni Bordatchev, a research officer with the organization.

Bordatchev stresses the importance of laser technology to machining features for micromolds. “Laser material removal technology allows us to have a cutting tool with a diameter focus of one micron, which is one-thousandth of a millimetre,” he said. “We work with very short pulse lasers that operate with pulse widths in the range of nanoseconds, picoseconds and femtoseconds.”

As an example of a successful collaboration with a plastics processor, Bordatchev points to a recent NRC-IMI-London project undertaken for auto part manufacturer Axiom Group Inc., of Bolton, Ont. Bordatchev and his team, Hugo Reshef and Marco Zeman, created core and cavity inserts for a monolithic air inlet, traditionally assembled with a metal mesh screen and a plastic molded part. “We were able to break new ground in the area of microtooling by using laser micromachining and micromilling technology to create such plastic parts, with a one-piece monolithic body micromesh having a wire diameter as small as 0.3 millimetres,” he said.

A key component making laser micromachining more efficient has been combining it with micromilling. “Traditionally, micromolding of dies were fabricated by conventional milling, which has limitations in terms of achieving dimensional tolerances,” said Dr. Suwas Nikumb, group leader. “The option we’ve adopted is to integrate the two processes, allowing us to increase the machining speed.”

Not all of the organization’s micromachining involves use of lasers, however. The NCR-IMI-London team also employ micro-EDM, a machining method primarily used for hard or conducting metals. Micro-EDM is especially well suited for cutting intricate contours or delicate cavities that would be difficult to produce with a grinder, an end mill or other cutting tools, Nikumb said.

“Our group collaborates with research facilities from the NRC-IMI in Boucherville, Que.,” Bordatchev said. “In the end, the synergy of our research and micro/nanomanufacturing strengths and capabilities can bring real benefits to Canada’s plastics industry.”

NCR-IMI-London (London, Ont.); www.imi.nrc-cnrc.gc.ca; 519-430-7107