Tip of the Day 40: How Controls Depend on it

I hear after sending yesterday’s tip that I got a little carried away with too much information in one message. If so, you can just file it for later reference if you need it.

Today, in more abbreviated form, we discuss how controls depend on sequencing.

  • Pack to Hold Transfer

    This is the control least sensitive to sequencing. It will turn its output on when the pressure setpoint is above a threshold and off when below 95% of it. Even if you wire sequence inputs incorrectly it will still work. Of course if the Injection Forward signal comes on part way into the cycle then the cavity pressures may auto-zero at the wrong point creating wrong thresholds. If you use volume to transfer then a good Screw Run signal will ensure proper zeroing.

    V->P transfer has an internal setting that you can use to force Control Output / V->P transfer off at the end of injection forward. If the setpoint is still above the threshold it will stay on anyway. But if you want it synchronous with the machine then you need a good injection forward signal.

  • Valve Gate Control

    It is essential that you have good Injection Forward, Screw Run and Mold Clamped Seq. Module Inputs to run this control. Unlike V->P it depends heavily on knowing the stages of the cycle in order to arm / disarm valve controls so as to avoid chatter and provide for re-open control.

  • Basic 3-Stage Control

    Must have good Injection Forward and Screw Run signals because it uses these to start the cycle and zero the screw. Unlike V->P Transfer it cannot run on just a threshold basis any time regardless of sequencing. It is intimately connected to the actual hydraulic valve on the machine and so it must be properly synchronized with the machine’s sequence.

  • Shuttle Control

    The Shuttle Control only needs correct the Seq. Module Input / Shuttle Position(s) and Injection Forward to work. It checks the shuttle position at the start of each cycle (Injection Forward)

  • Alarm Settings and Diverter Control

    Of course your set alarms depend on the proper computation of values. If sequencing is incorrect you will get incorrect values.

    Beyond that the Alarm Settings tool does its computations at the end of the cycle. So it needs a consistent end in order to do the work and fire the Diverter Control outputs at the same time on each cycle. As long as the process is set up the same every time then any end of cycle will work.