Two-shot injection moulding process is where 2 materials are ‘over moulded’ in one moulding cycle and this process requires specialized injection moulding machines. The word ‘shot’ refers to the volume of material injected into the moulding cavity. What happens in two-shot injection moulding is that an initial part is moulded and when it is finished a second part is inserted which will form the remaining part of the moulding. For the two-shot moulding process to work both parts must be similar (chemically) or bonding will not occur. Two-shot injection moulding can be used to bond a part of hard material with another of soft material. The process consolidates the moulding of two components in a two cavity mould. It can greatly enhance the appeal of the product in terms of feel, colour etc. Two-shot moulding offers many different design opportunities.
It is ideal for buttons and switches, handles and grips and caps for containers. Toothbrush handles are generally produced this way.
The most sizable benefit of two shot moulding is that a part can be composed of two separate parts while using one moulding process instead of two. This greatly reduces cost as it is far more economical and effective than having two separate injection moulding processes creating the two components. An engineer or industrial designer will design the desired part and then a tool maker will craft the mould that is needed to produce the components that are needed. Precision-machining is used to make the mould. The moulds are composed of either aluminium or steel.
A material compatibility chart is consulted to check which polymers will adhere together and which polymers are not compatible. It also removes the risk of contamination, which poses a problem when using two separate moulds. The two-shot moulding process also creates a far stronger bond than the same product or part being produced in two separate moulding processes. One of the other benefits of the two-shot moulding process is that it can deliver plastic products which are multicoloured and which is far more effective than a painting process which may wear off after time. With the two-shot process you can have more complex parts with added functionality. You can also have hard plastic combined with softer plastic. The integrity of the product is much stronger. Two-shot plastic moulded products are far more durable in general and are dust and shockproof. The process is also great for creating non-slip surfaces, air conditioning seals and gaskets and soft handles for electrical equipment. Logos can be fashioned with this process that will never wear away unlike painted-on logos.
At Automatic Plastics we do our very best to offer quality plastic parts across a wide range of industries using this process. Contact APL regarding your two-shot injection moulding needs we’re very happy to talk with you regarding your requirements and can offer you a highly competitive quote.