Process Control

Summary

General principles of more traditional process control industries are increasingly being applied to the injection moulding manufacture process. In Section 1 of this chapter, recent developments in process control, particularly with regard to the move towards distributed intelligence, are outlined. The application of these ideas to injection moulding is examined in Section 2 and an overall block diagram of machine measurement and control units communicating to a central unit is described. The three main control units—temperature controller, velocity/pressure profile controller and programmable logic controller—are examined in Sections 3, 4 and 5. Section 6 describes an alarm annunciator unit and a production monitor unit is described in Section 7. Section 8 discusses the handling of input signals and Section 9 the power control units for the main hydraulic and electric circuits. Having looked at the component parts in detail, the overall machine monitor and control unit and its computer interface are outlined in Section 10. Overall production control for a complete moulding shop is discussed in Section 11 and some advanced control strategies are briefly discussed. Finally, in Section 12, there are some general considerations of how things may develop in the future.