Villingen-Schwenningen, 10.02.2014

Polymeca AG has been manufacturing high-precision axle systems for over 20 years using conventional grinding machines. By building an innovative manufacturing facility, consisting of four fully automated precision grinding machines for internal and external machining with up to triple match grinding, the old-established Swiss company has now written a new chapter in precision and process reliability. The most important effect of the new production line is the process reliability achieved in large-scale series production, with a machining accuracy of up to 0.001 millimeters guaranteed even on unmanned shifts at weekends.

Pre-process, in-process and post-process measurement from a single source

This exceptional level of precision has been made possible by MOVOLINE, the new generation of process metrology from the Jenoptik Industrial Metrology Division. First, pre-process measurements in match and triple match grinding are used to determine the exact target values for machining the axles. In the grinding centers at Polymeca inner diameters high-precision are measured by pneumatic HOMMEL-MOVOMATIC measuring arbors in a flexible and cost-effective process, as well as at high clock rates.

For the in-process measurements, HOMMEL-MOVOMATIC DM200 digital gage heads and HOMMEL-MOVOMATIC DP200 digital axial positioning heads have been installed. These heads allow reliable measurements to be taken of outside diameters and passive axial positions, even under the most unfavorable machine conditions. External influences on the grinding process can be minimized as a result to ensure high-precision machining. Also impressive is the state-of-the-art digital technology featured in the new generation of in-process measuring systems. This technology is not offered by any other manufacturer. A crucial advantage of digital data transfer is the fact that, in comparison to conventional, analog systems, the measurement results are transferred free of interference regardless of the cable length, and even under the toughest conditions. Beyond that the new generation of measuring heads allows a significantly more compact design to be used. Depending on the axle type, in the Polymeca grinding centers, up to five in-process measuring heads for diameters and an axial positioning head have been combined within the tightest of spaces.

In fully automated grinding centers, sophisticated process metrology is required to achieve these narrow tolerances of up to 0.001 millimeters. Immediately after the grinding processes are complete, post-process measurements are taken in the grinding machine using the same measuring device. Roundness checks and length measurements are also completed at this point. These checks are carried out for quality control purposes, as well as for statistical process control and quite simply for readjustment or for trend correction to compensate for thermal influences, grinding disc wear and so on. By combining in-process and post-process measurements in a single measuring device, no additional post-process station is required.

When it comes to operating and displaying all measurement control functions in the entire facility, HOMMEL-MOVOMATIC ESZ400 measurement and display instruments represent state-of-the-art installation solutions that meet the toughest requirements.

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