Plasticating refers to conversion of plastic granuals to flow-able melt. It happens inside the screw barrel assembly of the injection unit in the Injection Moulding Machine.
- The plastic granules move inside the screw channel when screw is rotated.
- The screw has three sections. FEED ZONE, COMPRESSION ZONE and METERING ZONE.
- In the compression zone the material is gradually compressed. It therefore rubs against the barrel wall. This sets up shearing forces on the material.
- Plastic material under shear changes its viscosity. This is SHEAR THINING characteristic of plastics.
- Melt is then homogenised in metering zone.
At the tip of the screw, non-return valve is fitted. It allows the melt to flow ahead through this valve while screw is rotated.
Non return valve does not allow the melt to slip back through it to the screw channel.
To see Metering Stroke