Multivariate process adjustment by boundary contraction and taking the cost of each setting parameter into account
Résumé
The adjustment problem of a process, which creates a scatter and a drift on the characteristics of its products, is extremely common in industry. Although old, it still has no satisfactory solution. To solve it, this problem is first formulated on a direct variational model, which it is always possible to establish for such a process. Control limits and a target are to be chosen for each of the product's quality characteristics. An adjustment is sought if, at least, one characteristic of the last product is outside its limits. It is calculated by optimizing a problem of contracting the limits containing the characteristics towards their targets. Applied to a simulated production of one hundred and fifty workpieces, the "boundary contraction adjustment" results in two times less adjustments than the method of "minimum mean squared error" and, especially, makes it possible to control, automatically , the quality of all the characteristics.