The breakdown of machines lead to the lateness of parts and the change of schedules. Its treatment is very important problem in the shop floor control system. In this study, we present an algorithm minimize the lateness, earliness and change of schedule by controlling machining speed of available machines. Production time and production cost required to manufacture a piece of product are usually expressed as a unimodal convex fuction with respect to machining speed, and each has its minimal point at the minimum time speed or the minimum cost speed, and a speed range between these two speeds is called 'efficiency speed range'. Therefore, the algorithm determines the machining speed in the efficiency speed range. An example is demonstrated to explain the algorithm.