The three principles of quality control – for triple quality assurance

The first principle is basic clearance of the manufacturing process. Before production commences, toothing deviations to DIN 3962, as well as other dimensional specifications such as tooth crest diameter, tooth base diameter and tooth thickness of the part to be approved, are determined to highest precision using a modern tooth measuring centre. This measuring process is time-consuming but essential to obtaining an overall picture of all individual toothing deviations and irregularities or manufacturing process problems. If necessary, manufacturing machinery process parameters must be modified so that all strict tolerances are met.

The second principle is constant process monitoring. At ZEITLAUF^® antriebstechnik this is based on periodic process control (PPC), an intelligent and cost-effective quality assurance tool used as an alternative to the normal statistical mass production monitoring processes.

This entails checking the first and last parts of defined production batches. The toothing product features compared are dimensions and functions such as rolling variations. Only if the test results are positive can it be reliably assumed that production between the first and last part of the batch went without problems and that the parts now approved for further processing conform to specifications. If a deviation is identified on the last part, then a problem has presumably occurred during the run, i.e. since the first part was checked. This results in up to 100 % checking and sorting and to remedying the problem at once.

The third principle is an extra random check on the day’s production. Gearwheels are taken at random, measured and checked to make sure they conform to quality requirements. Only if the complete day’s batch of gearwheels produced by a production room shift passes this test is it released for further processing.