Novel Artifacts Using Simple Geometries for Evaluation of a Gear Measuring Instrument

Evaluating Gear Measuring Instrument (GMI) performance is difficult, even using a master gear, because manufacturing such a gear with the ideal involute form is difficult and accuracy cannot be guaranteed. To evaluate GMI performance, we propose artifacts using simple geometries such as planes, spheres, and cylinders whose form deviates little and that are easier to manufacture than a master gear. We estimated sphere, plane, and cylinder form deviation to be less than 50 nm. For profile evaluation, we developed a Double Ball Artifact (DBA) [1, 2] consisting of a base plate and two spheres. For helix evaluation, we developed a Wedge Artifact (WA) [3, 4] consisting of a plane and sphere. For pitch evaluation, we developed a MultiBall Artifact (MBA) [5, 6] consisting of a plane and multiple spheres. The GMI measures these instead of a gear, and we compared results to mathematical results, with the difference between measured and mathematical results showing GMI measurement capabilities. Evaluation uncertainty is a few hundred nanometers. We present the artifact concept and GMI measurement and evaluation results using these artifacts.