Today Coordinate Measuring Machines are offered by a number of manufacturers in all kind of sizes and with all kind of measuring errors. In order to choose the most suitable 3D measuring machine for your individual requirements we recommend following two basic steps:

Step 1: Determine the required measuring range of the CMM

To be considered: the dimension of the biggest part, the fixture, the diameter of the probe head as well as the length of the longest stylus.

As the example below shows, some parts require a 3D coordinate measuring machine with a much bigger measuring range than the actual part dimensions.

Example: Minimum required measuring range in X: 1660 mm

Step 2: Determine the maximum permissible CMM errors E, P and THP

All features to be inspected (Distance, Diameter, Form and True Position) are compiled in a chart, together with their tolerances. Then the CMM specifications E, P and THP (according ISO 10360) which still ensure a sensible ratio of "Tolerance to CMM error" can be calculated.

Example: Comparing the "E" specifications of two Coordinate Measuring Machines for given distances and tolerances. 

Based on the maximum permissible CMM errors E, P and THP calculated in the above chart and with the minimum measuring range determined in step 1 the most suitable 3D Coordinate Measuring Machine can be found.  Hexagon Metrology offers a free, unbiased analysis of the minimum required measuring range as well as the maximum permissible CMM errors, based on your part drawings.

All you have to do: Send your drawings or your CAD file to your local representative, listed under Contacts.