Phase 1: Injection
Speed counts during the injection phase. Process needs to deliver 95%-98% of the thermoplastic material into the mold before the material cools and freezes off flow. Precise timing and flow rate is vital to delivering material uniformly throughout the mold, regardless of varying dimensions and thicknesses. Thermoplastics have a flow pattern called Fountain Flow. The material against the mold wall is always cooling and solidifying, thus restricting flow and causing motion to occur in the middle of the wall thickness.
Phase 2: The Pack
Towards the end of the injection phase, the pack phase squeezes the last bit of material into the mold to eliminate voids and porosity. It ends when the mold gate is solid or frozen. A Gate Freeze Off study determines the ideal time for the pack phase.
Phase 3: Cooling
The cooling phase is the time you wait for your product to solidify before opening the mold. This timing is crucial because it affects both product quality and profitability. Open the mold too soon and the part may change from its intended shape. Wait too long and you waste valuable production time.
Read More at Hi-Tech Talk
If your interested in other topics regarding Thermoplastics or Thermosets, go to HT Talk. This is where we post articles on technical aspects of injection mold tooling, molding, machining and assembling thermoplastics. www.hitechmoldtool.com/ht-talk