Hes-so Valais

High precision dimension measurement for the fabrication process in milling machining

The goal of this work is to allow a precise (1-10µm) measurement of bar turning pieces. The dimensions of the pieces under study were smaller than 50mm.

We have developped an illumination system which is specifically designed for a telecentric objective. Furthermore a special positioning system, which allows an integration of the measurement in a fabrication process, was added to the system.

Thanks to this arrangement, it is possible to follow and master the fabrication process with a relative tolerance of the dimension of about 0.07% for the process and about 0.015% for the final control.

Object and illumination

The object holder consists of two glass plates glued together.
A black coating ensures that no light can go through the interface and thus gives extra rays in the image.

The object measured by the vision system. L 1 is 15.7 mm

The real object as seen by the camera with the back illuminnation (at 730nm)
without a red flter (left) and with (right).