Parts of a Typical Molding Machine:
Hydraulic injection cylinder
Molding Process :
- The plastic raw material is stored in the hopper.
- The plastic falls on the rotating screw.
- It is conveyed forward by the flights of the screw and is gradually melted as it moves forward.
- When enough melted plastic has accumulated ahead of the screw, the screw stops rotating.
- The screw, acting as a plunger, pushes the melted plastic out of the injection barrel.
- The plastic goes through the nozzle, sprue, runner, gates, and on into the mold cavities.
- Packing occurred- a little more plastic is forced in after the cavities are full.
- packing continued until the gate freeze.
- when the plastic in the gate freezes, the pressure on the screw is released. The screw rotates back to melt and convey the next shot of plastic ahead of the screw.
- when the parts are cool enough to hold their shape, the mold opens, the parts are ejected, and the cycle is repeated.