Towards integerated jobbing-shop manufacture

Abstract

The introduction of the computer into manufacturing processes has made it possible to integrate individual machine tools into the overall manufacturing system. This paper outlines some results of research at Brunel University led by J. W. Rourke. A complete package was produced to enable jobbing-shop manufacturers to enjoy most of the benefits of integrated manufacture using a small/medium computer. The package will produce NC machine control tape, machining schedules, expected shop capacity, standard job production cost and price according to a pre-determined profit margin. The package is in two parts. The first part consists of a part-programming section comprising BRUNELCON (a conversational part programming translator), 2CL, and a post processor. The second part consists of a management section which includes the scheduling and cost predictors. The mode of operation is to input the job specification, which then allows interactive conversational part programming to take place. This results in the machine control tape, a graphical presentation of tooling layout and cutter centre line path, and the setting/operating instructions being produced by the computer. Information from this output, which provides the exogeneous variables for the computer's simulation in the predictor section, is stored on the common data base. The predictor then simulates the jobbing-shop performance, giving a choice of forward or backward scheduling methods, and uses the existing standard cost rates to evaluate the pre-determined job production cost and price. The simulator also indicates the optimum duration of variable manufacturing operation times for management control, and sequences the machine loadings by resource smoothing or levelling.