Roundness and straightness measurement

Measurement of roundness and straightness on the coordinate measuring machine with unrivalled accuracy. The patented HD raster scanning mode and the new RotaryScan HD are used in particular. A highly accurate telecentric lens, an air bearing rotary axis with an air bearing tailstock and a new correction method achieve minimal measurement errors in the range of 200 nm for reliable detection of roundness tolerances of up to 2 μm.

One application, for example, is the measurement of the straightness of the outer cylinder of control pistons for hydraulic applications. During the movement of the device axes – but without movement of the rotary axis –, the outer contour of the workpiece is captured with the maximum possible number of images. The overall image generated by superimposing the single images enables fast measurement "in the image" with increased accuracy.
To measure roundness, the image is captured while the rotary axis is moving. Measurement points are determined from the images of the various rotational positions, which are then calculated to form a circle. With up to 400 measurement points per second and measurement errors in the range of 200 nanometres, the accuracy of form measuring machines can be achieved with significantly less measuring time.
The Werth coordinate measuring machines thus enable a new level of performance in solving measuring tasks that could not previously be carried out on conventional coordinate measuring machines.