Traceable in-process dimensional measurement

Europe is the world’s largest producer and exporter of precision engineering production tools, such as cutting and milling machines. Millions of jobs in automotive and aeronautical manufacturing rely on these machines to reliably fabricate the complex components which underpin sophisticated products. The early identification of faulty components has the potential to increase productivity by 20%.

Many of the production machines incorporate measurement systems to confirm that components meet specification before they leave the machine. These measurement systems need periodic recalibration, where carefully controlled environments are used to eliminate the significant errors associated with shop floor temperature variations. Installed methods for confirming system performance on the machine itself would make measurements of complex shaped components more reliable and increase the early identification of parts nearing specification limits.

The EMRP project Traceable in-process dimensional measurement developed new reference materials and procedures for accurate, in-process calibration of installed measurement devices.

The project developed:

• Temperature stable reference materials with well characterised and complex geometries to simulate the intricate shapes of precision components to provide in situ measurement system calibrations.
• A portable climate simulation chamber, which can house a medium-size dimensional measuring machine, enabling evaluations of how changing temperature affects performance and measurement accuracy.
• Validated procedures for determining machine tool positioning uncertainties using the new reference standards, as well as developing methods for making temperature-dependent error corrections to minimise measurement uncertainties.
• Five best practice guides, which form the basis of a training course for industrial users on how to make measurements and determine factors that contribute to measurements uncertainty.

Spotting components that are nearing the edges of tolerance during the manufacturing process, and taking corrective action, relies on the ability to make continually accurate measurements. This in turn requires that instrument calibrations remain true and reliable, and that corrections matching environmental operating conditions are available for use. This project has given industry the tools and techniques needed to perform in situ calibrations of dimensional measurements, and verify that complex parts produced by machine tools meet specification. Companies in Finland and Slovenia have already benefited from project developments, giving improved accuracy for their manufacturing process measurements. Project procedures and investigations have also fed into new documentary ISO standards on geometric production tolerances, helping to improve dimensional measurements practices across Europe.

Robust on-machine measurement techniques will lead to more reliable and accurate measurements, enhancing machine productivity and reducing energy consumption by 30 %. Higher quality products and lower manufacturing costs will both help increase the competitiveness of European industry.

Coordinator: Klaus Wendt, PTB (Germany) 
For more information, please contact the EURAMET Management Support Unit:
Phone: +44 20 8943 6666
E-mail: empir.msu@euramet.org