Heat inserting is an example of the post mould process of inserting. The addition of inserts into a part increases the functionality of a part and can also increase the ease by which components can be assembled. The actual insert that is incorporated into the moulding can take a variety of forms and be either metal or a pre-formed plastic insert. A good example for the application of metal inserts is for instances where the part needs to be screwed to another part or to some other fixing. In this case the plastic might not be a strong enough material to be threaded, or screwed into, so metal (usually brass) threaded inserts are heat inserted into the part which can then provide the necessary strength.
The process of heat inserting a part is not very complicated but ensuring that each part is inserted in exactly the same way is more complex. To ensure that there is no variation in the location that the inserts are placed jigs are used to hold the work piece firmly in place. Each insert will be located individually by using a heat gun that heats up the insert and with it the plastic around it. This means the plastic becomes soft enough for the insert to be pressed into place and when the plastic cools again the insert will be held in place. The heat gun is also equipped with distance stops to ensure that every insert is positioned consisitently in the component.. To further ensure parts are inserted correctly rigorous quality checks are carried out on all inserted parts to ensure a high level of quality is maintained.
Benefits of Heat Inserting
- Increased functionality – by adding inserts to mouldings the part can more easily be used for its designed purpose. For example by adding threaded inserts parts can be easily be screwed to their fixings or other parts, increasing their functionality.
- Low part degradation – the process of heat inserting means that the heating/melting of the part is very localised to where the insert will be pressed in. this means that parts do not suffer warping, or any other distortion effects, due to being heated again.
- High level of quality – due to the known challenges with heat inserting extra measures are taken to ensure the processes is repeated to as high a level as possible, meaning part quality is kept very high.