THE DRIFT ELIMINATION METHODS IN GAUGES BLOCK MECHANICAL COMPARISON PROCEDURES
Gauge block calibration is one of the oldest high precision calibrations made in dimensional metrology. Gauge block comparison schemes are designed with a number of characteristics. The unknown length of a block is determined by measuring the difference between it and a reference block of the same nominal size and then calculating the unknown length. The sources of variation in measurements are numerous. Source of serious problems, which is not random, is the drift in the instrument readings. The instrumental drift can be obtained from any comparison scheme with more measurements than the number of unknown lengths plus one for the drift, since the drift rate can be includes a parameter in the model fit. This effect cannot be minimized by additional measurement because it is not generally pseudo-random, but a nearly monotonic shift in the readings. In this paper some techniques for drift eliminating of instrument are discussed.