Form tolerance verification using the Kriging method

Manufactured parts are affected by form and size errors, assessed against geometrical and dimensional tolerances. In the paper, we deal with a flatness tolerance which defines a zone between two parallel planes within which a surface must lie (ISO 1101). As a consequence, only few points, outer and inner ones, are relevant in verifying flatness. Given that just a finite number of points can be probed with Coordinate Measuring Machines (CMM), the algorithm we suggest to obtain an efficient estimate of the tolerance value is based upon Kriging models, and on a sequential selection of the points to be probed. We have discussed different approaches (different correlation functions selected on the basis of the technological signature, different criteria for selecting the next inspection point, different evaluation methods).