Sponsored By
Clare Goldsberry

June 17, 2016

1 Min Read
Werth CMM improves measurement accuracy of multi-material workpieces

In coordinate measuring technology with computed tomography (CT), the dimensional analysis of workpieces made of multiple materials is particularly challenging. Werth Messtechnik (Giessen, Germany) has developed a unique solution: Multi-Spectra-CT.

By combining several CT measurements (A and B) tuned to each specific material, artifacts are minimized (C and D) using the Multi-Spectra-CT.

Multi-material workpieces often include metal and plastic components, such as assembled plug connectors. The measurement task typically determines the position and bend angle of the internal metal pins. In a CT measurement, however, the metal pins often cause artifacts because of beam hardening and scattered radiation. Historically, these effects have made plastic enclosures much more difficult to measure.

The Win Werth measurement software in the Multi-Spectra-CT takes two CT measurements—with spectra tuned to a specific material—and computationally combines them into a single volume. This volume can be used to check dimensions in any desired cross section using 2D contour image processing. A patented method for local edge detection can also be used to derive a 3D point cloud for the entire workpiece.

By reducing artifacts, measurement uncertainty between different materials is minimized.

About the Author(s)

Clare Goldsberry

Until she retired in September 2021, Clare Goldsberry reported on the plastics industry for more than 30 years. In addition to the 10,000+ articles she has written, by her own estimation, she is the author of several books, including The Business of Injection Molding: How to succeed as a custom molder and Purchasing Injection Molds: A buyers guide. Goldsberry is a member of the Plastics Pioneers Association. She reflected on her long career in "Time to Say Good-Bye."

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