Key facts
The injection molding process explained step by step: clamping, injection, packing, cooling and ejection - plus the machine capabilities behind it at our 100+ press factory.
Every injection molded part – from a bottle cap to a battery housing – goes through the same five phases on every shot. Understanding them explains why molds cost what they cost and why process control decides quality.
The Five Phases of Every Shot
- Clamping: the mold closes and the press locks it with 80-1800 tonnes of force, resisting injection pressure
- Injection (fill): the screw pushes molten resin into the cavity in fractions of a second; 95-98% of the part fills here
- Packing (hold): added pressure compensates shrinkage as the part cools – this phase decides sink marks and dimensions
- Cooling: the longest phase; chilled water through the mold solidifies the part, and cooling design drives cycle time
- Ejection: the mold opens and ejector pins push the part out; robots remove and place it
Why Process Windows Matter
Temperature, pressure and speed interact. A “scientific molding” process finds the stable window where the part is good across normal material and environment variation – then locks it in with documented setpoints. That is why our production runs start with first-article approval per cavity and keep parameter logs per shift.
Machines Behind the Process
Our molding floor runs 100+ presses from 50T to 1800T in automated 24/7 cells with robotic takeout. Small connectors to large automotive panels – the same five phases, controlled shot after shot.