Manufacturing block diagrams and optimal adjustment procedures

This paper introduces a technique for modeling manufacturing systems using block diagrams. The blocks represent linear transformations of dimensionless noise vectors to normalized quality characteristic vectors. These block diagrams are used to model on-line adjustment procedures using generalized inverses. This adjustment strategy is shown to guarantee minimum quality loss as defined by Taguchi if the required adjustments have no active constraints, and is effective for coupled linear systems. The surface mount of large body packages serves as an example of the modeling techniques. Block diagrams of the surface mount process are developed for a production system incorporating on-line adjustments and for the same system without adjustments. Data from preproduction runs support the model's predictions of bias, variance, and yield.