Corporate Buyers Guide

Not all products can be placed on a table or a defined measuring station to be touched by a probe coming from an overhead crane or gantry. This measuring method is not acceptable if the product is tapered downward or has deep recesses.

The single arm probe is more like a 6 axis robot. The mounting point of the arm, an elbow type joint, the mounting fixture of the measuring probe plus the probe itself all have one or two axes of flexibility.

This type of coordinate measuring can be easily set up for quick measurement of odd shaped products. The key is a precise measurement from one point of the object to the reference point at the base of the arm. Every other measurement will be in reference to that point of the object. CAD type software will then identify and lay out the whole object.

The science of measuring an item by finding the coordinates of the key points of a product has progressed tremendously in recent years. This technology blends perfectly CAM and CAM.

The biggest progress in CMM machines has been in the software for the upfront programming plus analyzing the data collected. The second and not so visible progress is in the design of the measuring probe. The length, weight and flexibility of the probe is key to obtaining accuracies and repeatability of 10^-4 mm.

Measuring very large objects, such as car bodies, with coordinate measuring machines in a manufacturing environment requires more than one measuring probe. Each probe measures more than one point on the object. The arms or the frame holding the probes have to be connected with material that has predictable thermal characteristics so that thermal expansion does not create an accuracy problem. All the data from the points measured can be downloaded into a CAD type program and create an image of the object. The allowable dimensional tolerances of each point measured can be determined and points out of tolerance can be identified and corrective action can be taken before the object moves to the next point in the manufacturing process.