Automated Part Fixtures for Lightweight Applications Including CMMs

Many machining and measurement operations require the part to be held in a fixture for a stable and repeatable process. Using fixtures that are specifically designed and built for a specific part becomes expensive when many different types of parts are to be processed. Flexible part fixtures are time consuming to set up and generally do not offer the part stability that larger parts often require.

The current state of the art in flexible part fixtures for lightweight applications include expensive adjustable towers positioned manually by the operator or automatically by a coordinate measuring machine (CMM) to component fixtures consisting of v-blocks, c-clamps, double-sided tape, vacuum cups, and spacer blocks. Some fixtures are positioned in a grid pattern thus limiting the fixture placement to the spacing of the grid. Other systems require the fixture to be locked down to the machine base with a clamp but placement is only limited to the size of the fixture base.

A part fixture system that can automatically position itself to accept parts of varying size and weight would eliminate many time consuming steps in the flexible part fixture buildup process. A part fixture system that can automatically position itself anywhere on a steel plate to within 0.0254 millimeters would eliminate the drawback of grid -placement and allow better holding of complex parts. This paper will describe such a system.