Comparison of Aspect Ratio, Accuracy and Repeatability of a Laser Line Scanning Probe and a Tactile Probe

Laser line scanning is a laser based measurement method to acquire dimensional information of a workpiece. The most common applications are found in e.g. automotive and medical industry. The advantages of laser line CMM probing are a high data density and a high measurement speed. This makes the probe ideal to measure three dimensional free form surfaces. To align freeform parts in a precise manner however, features (e.g. cylinders, spheres) are used to allocate the position. The newest generation of laser line scanners can have an MPEP of below 10µm. The first part of the paper presents a reference object with drilled holes of different diameters. The influences of the diameter of the feature and the in-plane viewing angle on the measuring depth range are investigated on this reference object. The results can then be converted to an aspect ratio limitation that restricts the feature dimensions for full inspection. The second part compares the accuracy and the repeatability of a Nikon Metrology LC60Dx digital laser line scanner and a Renishaw TP200 touch-trigger probe, using two case study objects that incorporate cylindrical features. The experimental case takes into account different surface finishes and the previously acquired results on the aspect ratio of the measurement. Both investigated sensors are equipped on the same CMM and are operated with the same software.

Publication year:2014

Accessibility:Open