Insert moulding is the process where a plastic material is moulded over, around or even inside a metal insert. Examples are the soft-grip rubber handle on a pair of scissors or the plastic covering on a pc connector. It's easy to forget that these day-to-day items are produced by a pretty specialised plastic injection moulding process.
Why is insert moulding so special ?
Your injection moulder needs to know how the insert and the plastic material will respond to the moulding process, otherwise the results can be very poor indeed. Here's a guide to some of the most important considerations to get a good quality insert moulding.
1. Plastic injection pressure
If the injection pressure is too high, the insert will get damaged. If it's set too low, the plastic material might not form a cohesive bond with the insert and will start coming loose when the part is in use – for example the handle coming off that knife from the bargain shop.
2. Plastic material temperature
If the injection temperature is too high the insert might be distorted or damaged. If it's too low, the plastic material will flow too slowly and the part will not get completely encapsulated, or the plastic will be so hard that it can displace the insert.
3. Injection mould tool design
The mould tool needs to be designed for a good result. Air vents need to be carefully designed to avoid air bubbles which will prevent adhesion. And thin layers of plastic material may give an acceptable result at first, but can easily start peeling off later.
How can Toolcraft help ?
There are more factors at play, but you'll get the gist of the complications that can occur. However, here at Toolcraft, we have years of mould tool design and insert moulding experience to help you produce your insert mouldings to excellent quality. We also specialise in making insert moulding financially achievable for shorter run products.
We have a lot more plastic moulding advice for you to explore, or if you're ready to benefit from our experience,