Sandia has designed and is fabricating several LIGA (Lithography Galvonoforming Abforming) test mechanisms. The LIGA test mechanism is a ratchet drive mechanism consisting primarily of pawls, cams, and springs of various nickel alloys ranging in size from about one-half millimeter to tens of millimeters, all fabricated using the LIGA process. The purpose of the test mechanism is to study tribology and performance attributes of LIGA mechanisms. To assemble the test mechanism, subassemblies are made by inserting force-fit pins into stacks of piece parts. These pins are cut from 170μm wire and range from 500 to 1000μm in length. Human insertion of these pins is extremely difficult due to their small size and tolerances required to perform the force-fit operation. To date, Sandia has developed the tooling to permit fabrication, bulk handling, and force-fit insertion of pins with the operator-guided automation required to achieve micron-scale tolerances using hybrid force/position control algorithms.
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