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A Bicycle Built for a Flea
Today's small wire EDMs can produce ultra-fine features
Karen Field, Editor-in-Chief -- Design News, June 26, 2009
Losone, Switzerland – To demonstrate just how far the capabilities of small wire EDM (electrical discharge machining) have come in the past decade, researchers at Swiss-based GF AgieCharmilles produced this micro-size mountain bike. First introduced some 30 years ago, EDM uses electrical discharges that form an arc between an electrode and work piece to achieve a desired shape.
The tiny cycle was machined out of 1-mm-thick Inox stainless steel using a 0.020-mm wire. The smallest internal radius measures a mere 0.013 mm, with a tolerance of +/- 1 μm.
One of the biggest obstacles to overcome in achieving these ultra-small features, says Head of R&D Micro Machining Dr. Ivano Beltrami is controlling the micro gap. "That means first being able to electronically measure a distance between electrode and work piece at the level of only a few (two to ten) micrometers and second being able to keep the gap width relatively constant."
It's particularly difficult, he says, because of the particle contamination in the dielectric and the stochastic nature of the spark formation.
Asked if the wheels on the bike actually spin, Beltrami says "No, it's challenging enough to actually have the wheels at all."
While there is no practical application for a flea-sized micro bike, GF AgieCharmilles is seeing a slew of commercial products that are getting downsized – including 3-D mold inserts for electronic devices, punching tools for micro gears and lead frames and micro diaphragms for optical applications.
So can things get smaller? "The biggest limitation to further advancements in the technology is the current market size, which is still relatively small and in turn limits the investments," says Beltrami. "But from a technical point of view, even smaller structures are feasible."
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Sure, but let's see a photo of the actual object!
Captain James Brock - 2009-14-7 13:12:18 EDT -
The flat side of a normal pencil is about 4mm wide. That should give a rough indication of scale.
jimmythefly - 2009-13-7 16:33:31 EDT -
How about a photo along side some commonly recognizable object, in order to show scale?
Chris - 2009-13-7 15:28:00 EDT
