Background on Plastic Injection Moulds

Plastic injection moulds refers to the tooling that is used to produce plastic products and parts. Plastic injection moulding is a billion dollar industry that continues to grow through the years. What separates the really good companies from the mediocre ones are their ability to work with a wide variety of materials when developing the mould to be used for the plastic products and parts. As far as good quality plastic injection moulds, NSW companies are up there with the best.

The actual mould has two components, the injection mould and the ejector mould which are two different plates. Plastic material goes into the mould via sprue found in the injection mould. The sprue bushing is sealed tightly on the nozzle of the moulding machine’s injection barrel in order to allow the molten plastic to be transferred from the barrel onto the mould or the cavity as it is sometimes referred to.

Molten plastic is poured into the cavity through machined channels onto the faces of the injection and ejector moulds. The channels are called runners as they allow the material to run through them onto the mould. The amount of resin or plastic material that goes into the mould is an exercise on precision. Sometimes trapped air is compressed by the material and goes to the corners of the cavity. When this happens, filling is prevented and other defects take place as well. The trapped air can also cause the material to ignite and get burned.

After the moulding is done the moulded product is on the ejector side so that if falls freely as it is ejected from the mould. Ejector pins found in the mould pushes the finished product out of the mould and the product is ready for cooling. This is done by passing water or any other coolant through holes drilled in the moulds. The coolant absorbs the heat and keeps the mould’s temperature at a rate where it can solidify the product efficiently.

For easier maintenance, the cores or cavities are broken down into pieces and sub-assemblies, both called inserts. The inserts are interchangeable and when they are alternately used, they can be used to create multiple variations of one single part.

Author: Todd Johnson
Email: Todd@australianwebsitedevelopment.com.au
Mobile: 0449 041 815