AbstractPlastics injection molding is a complex, multi‐variable process which has not yet been clarified. The hardware controller is difficult to build without a realistic mathematical model. One powerful technique for solving such a difficulty is to employ digital control technology which can utilize sophisticated control strategies in order to optimize the system performance. Machine operation and resultant production can be tightly controlled by using computer monitoring, data storage and data logging. This paper presents elements of the various problems that process engineers may encounter in designing a computer‐controlled system for plastics injection‐molding machinery. The variables of the process and a functional analysis of process control are discussed. A hardware system design; including specification of computer, selection of peripheral devices, system design, and input/output interfacing; is presented.