PROCESS ADJUSTMENT FOR ASSEMBLIES Should Components, or Assemblies, Be Made to Specifications?

After the design and construction of manufacturing tools, adjustment is often necessary to reduce mean deviation from target of product dimensions. We for­ mulate a stochastic dynamic program to find the optimal adjustment policy when the adjustment outcome is uncertain. The optimal policy minimizes the sum of adjustment cost during pre-production and quality cost during production. The formulation is developed for a single process and for two processes producing components for assembly. In the single process case, sufficient conditions are given for the optimal policy to have an upper and lower control limit form. In the two process case, we compare separate and combined policies and give an example where appreciable savings can be realized from a combined policy.