In general, a closed control loop is used to bring a given physical quantity to a desired setpoint and to maintain it there by measuring and readjusting the actual value.
In closed-loop process control we speak of a closed control loop.
Compared to open-loop process control, the closed-loop process control parameters are not processed in real time but adaptively. This means that the parameters are not calculated until the end of the current cycle and are transferred to the machine control system via a host computer interface. This way, the new setting values of the injection molding machine for the following cycle are communicated via a protocol. In the process, setting profiles are transmitted such as for the injection speed, holding pressure, cylinder or hot runner temperatures or connected temperature control units.
Compared to open-loop process control, closed-loop process control takes a more holistic approach. Closed-loop process control permits much deeper intervention in the injection molding process, and considerably more parameters can be influenced. However, closed-loop process control also requires a much larger infrastructure.