Decoupled Injection Moulding Setup Principles for Technical Parts
Decoupled injection moulding decouples volumetric filling velocity from packing pressure to achieve tight tolerances and repeatable technical part production.
Velocity to Pressure Transfer
Meaning
A critical processing switchover point transitions injection moulding machine control from dynamic screw speed filling to static hydraulic hold pressure. Process engineers configure velocity to pressure transfer to prevent tool over-packing while ensuring ninety-five to ninety-eight percent cavity volume filling during speed control. Switchover occurs based on screw position, hydraulic pressure, cavity transducer signals, or elapsed stroke time.
Improper transition timing causes part flash, short shots, structural sink marks, or extreme molded-in stress.
Switchover Mechanism
Position-based switchover provides the most reliable transfer mode under steady material viscosity conditions. Executing velocity to pressure transfer at the precise millimeter of screw position stops dynamic forward movement just before melt reaches end-of-fill. Viscosity variations from regrind blend changes cause pressure spikes if position transfer remains fixed without hydraulic pressure overrides.
Real-time cavity pressure transducers offer optimal switchover precision by triggering transition the instant melt compresses against far cavity walls.
Flash Prevention
Premature transfer leads to short shots due to insufficient volume delivered during the high-speed filling phase. Delaying velocity to pressure transfer causes pressure spikes that force tool parting lines open, generating thin plastic flash along part edges.
Cavity Pressure
Peak pressure inside the mould dictates part density and final volumetric shrinkage. Optimizing velocity to pressure transfer parameters stabilizes part dimensions across varying resin lot viscosities.