Last March, officials at Micro Waterjet held the U.S. debut of a new abrasive waterjet capable of micromachining with the precision of a laser, minus the threat of thermal damage to the workpiece.
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| The AWJMM can provide a cutting accuracy of 0.0004" and a surface finish as fine as Ra 1.6μm. |  |
The Abrasive-Waterjet-Micromachining (AWJMM) system from Micro Waterjet LLC, Huntersville, N.C., features a cutting accuracy of 0.0004", a positioning precision of 0.0001" and a surface-finish capability as fine as Ra 1.6μm, depending on material and thickness.
“One of the biggest advantages [of AWJMM] is the lack of a heat-affected zone,” said Steve Parette, Micro Waterjet’s senior project manager-sales. “If it’s important to the customer to reduce heat, this technology takes EDMs and lasers out of the competition.”
Developed in 2003 in Switzerland, AWJMM is designed to fill a gap in waterjet capabilities. Conventional waterjet technology’s lack of cutting precision has historically barred it from micro-applications. But the AWJMM’s ability to handle tight tolerances eliminates that barrier. As an abrasive waterjet, the AWJMM also is capable of micromachining materials such as aluminum oxide, carbon fiber and phenolic resins—all impervious to EDMs and lasers.
Key to the new waterjet’s accuracy are Micro Waterjet’s proprietary workholding and positioning systems, said Parette. The company’s workholder, he continued, involves “clamping the parts down rather than setting them on a base. A lot of the conventional waterjet machines have what they call bricks; you just set the workpiece on the brick and do the cutting. That’s not a stable setup, and if you have materials susceptible to the turbulence of the water underneath, they’re going to move around on a micron level.”
The positioning system is designed to ensure the nozzle accurately directs the abrasive (garnet or olivine) and water at the part at 60,000 psi. “[The system] provides the NC motion to cut the shapes,” said Parette. “The X, Y and Z axes make up the total positioning system, and that combination holds an accuracy of 3μm.” Standard kerf widths are 0.3mm, but can be as narrow as 0.080mm when cutting soft materials such as silicone, neoprene and Viton.
The real challenge for AWJMM is changing old ways of thinking, said Parette, adding that many engineers are convinced that waterjets cannot hold tight tolerances. “When you talk to them about waterjets,” he continued, “they automatically think, ‘Well, I’ve already been down that road, I don’t know if I need to look at it again.’”
To date, AWJMM technology has successfully micromachined a range of materials, including synthetic substances, nonferrous metals, steel and chrome alloys, titanium and composites.
Industries using the new waterjet include medical technology (titanium implants, tool-blanks, prefabricated mounting plates, rubber mountings, instruments), watch making (housing outlines, gear wheels, watch hands and clock faces), motor sports (seals, ventilation grids, complex carbon fiber parts), electronics (chip support, sensors, printed circuit boards, complex chip sets) and arts (jewelry, inlay, inscriptions, templates for lighting and illumination).
New abrasive waterjet for micro applications
