Metrology Artifact Design

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Abstract

Research Method

Results

Supporting Materials

Abstract

Part acceptance based on dimensional inspection by comparison to tolerance specifications is influenced by the static and dynamic errors in the inspection instrumentation, typically a Coordinate Measuring Machine (CMM). Traditional calibration artifacts are used to determine static influences due to machine geometry. The goal of this project was to design and fabricate a calibration artifact that will test a CMM both statically and dynamically. The artifact developed is a diamond turned, electroless nickel plated, 17-4PH stainless steel ring gauge (150 mm ID, 200 mm OD, 25 mm thickness). Sinusoidal features (5µm amplitude) were machined on the inside and outside diameter of the ring using a fast tool servo. The feature wavelength varies linearly along each surface between the longest wavelength (6.4 mm) and shortest wavelength (0.4 mm) without discontinuities. A reference flat was also machined on the ID and OD. The dynamics of a CMM under a specific set of measurement conditions can be found by computing a transfer function between a measurand of the ring gauge and the accepted “true” shape of the gauge. This allows an operator to devise a measurement strategy for a part that does not exceed the dynamic capabilities of the CMM and to predict the error in a measurement.

Supporting Materials

Metrology artifact design (21 Mb Power Point)