Coordinate Measuring Machines (CMM)

Compare COORDINATE MEASURING MACHINES. The size of coordinate measuring machines can range from a few centimeters to over a meter for typical laboratory or industrial CMM applications. The CMM (coordinate measuring) volume space under the measuring bridge has to be larger than the measuring range specified for any given model. Most important is the height available under the probe tip (Z axis) and the width on the table (Y axis). The work surface of most models is made of granite. The X and Y axes are moved with linear electric motors or ball screws and ride on air bearings. The Z axis is driven by ball screws or pneumatically. The software allows the programming of coordinate points to be measured of shapes and contours that the probe will follow.

The degree of difficulty to program the measurements will depend on the software, the type of measuring probe and, most of all, the complexity in shape of the item to be measured. For quality assurance and random rampling of more than one shape, the ease of use of the software is important.

For shop floor use, the temperature stability of the coordinate measuring machine is important. The use of granite gives the CMM mass which reduces the sensitivity to vibration. Synthetic granite, a mixture of granite beads held together by an organic binder, has lower thermal expansion so that in addition to vibration, it is also less sensitive to temperature fluctuations.

Single arm CMMs and bridge type CMMs with over one meter travel in any direction fall under the custom or special made and are not listed here.