The injection moulding process involves injecting molten plastic into a mould cavity to produce plastic parts. The key principles of the injection moulding process are:
1. Plasticize the resin - The plastic resin pellets are first fed into the injection moulding machine and melted in a heating chamber called the barrel. This plasticizes the resin by melting it into a fluid state.
2. Inject the melt - The plasticized resin is then injected into the mould cavity under high pressure using an injection screw. The mould cavity forms the shape of the desired plastic part.
3. Pack and holding pressure - After the initial injection, a holding pressure is applied to pack the melt into all corners of the mould cavity and prevent shrinkage. This ensures good dimensional accuracy.
4. Cool and solidify - The mould is cooled by a cooling system like water channels to solidify the melt and impart the final shape to the plastic part. The cooling time also affects the properties of the part.
5. Eject the part - Once solidified, the moulded plastic part is ejected from the mould using ejector pins to retrieve the finished part.
6. Mould preparation - The mould is prepared again for the next cycle by closing the mould, checking for flash and properly aligning the slides.
So in summary, the key principles involve melting and plasticizing the resin, injecting it into the mould under pressure, packing the melt, cooling and solidifying the part, and then ejecting the finished part from the mould. These steps are then repeated in a continuous cycle to produce multiple parts.
By controlling different parameters in this process like temperature, pressure, cooling and cycle time, plastic parts with the desired properties and performance can be produced.
Hope this overview provides a helpful explanation of the basic principles of the injection moulding process! Feel free to let me know if you have any other questions.
