Optimal Scheduling of Products with Two Subassemblies on a Single Machine

We consider a single machine job shop in which subassemblies of two different types are made and then assembled into products. The time required for each type is known. A fixed changeover cost is incurred whenever the machine is switched over from one type to the other. We describe and analyze an efficient algorithm for minimizing the total flow time of the products. Applications to the automated manufacture of circuit boards are noted.