Deviations and tolerances of position in production engineering

Abstract

Increasing demand for quality on the one hand and competition and cost consciousness on the other hand are contrary requirements in modern production engineering. The knowledge of necessary and permissible deviations ( i.e. surface roughness, form errors and deviations of position) from the ideal geometry of workpieces exercises an influence on the economics of manufacture. This problem is of increasing and pressing importance at the present time because of shortages and rises in prices of raw materials and energy on account of which reject rates must be reduced and retouching work must be avoided as far as possible. The interactions between two or more features of a workpiece produce different deviations of position or (as described in ISO Standard 1101) “geometrical deviations of related features”: orientation, location and runout. Typical examples are for instance parallelism or coaxiality deviations. In the research project described in this paper the present author investigated the problem of deviations of position and workpiece accuracy. By means of the coordinate measuring technique many workpieces have been measured and the deviations of position of the various features have been determined. The evaluation of measuring data is the basis of a proposal for a guideline for permissible deviations of position under conditions of economical production.