The pilot dimension method: Reconciling Steering and Conformity in Workshops

Overview & Synopsis

In machining workshops, workpieces are produced according to dimensions known as manufacturing dimensions. For the same workpiece and the same manufacturing plan, several sets of manufacturing dimensions can be used but none satisfy simultaneously the two main missions workshops need to fulfil: (a) Ensuring conformity of products to their design dimension tolerances (also called blueprint tolerances) and (b) steering machines in order to compensate for tool wear. The set of manufacturing dimensions obtained from the design dimensions using the minimal chain of dimensions method is optimal for a conformity check of workpieces but is practically unusable for steering machines because of the complexity of its relationships toward the tool correctors and tools dimensions. The pilot dimensions method consists in, on the one hand, identifying and representing these tool correctors and these tool/program dimensions on the production drawings (besides the manufacturing dimensions) and, on other the other hand, determining their correction values through a mathematical set of relations after having measured the manufacturing dimensions on a workpiece. Doing so will strongly reduce adjustment time, reduce the number of workpieces used for adjustments and greatly enhance the quality of workpiece batches.