Overmolding is not a new manufacturing technology, but there is still some confusion about how to design for the two-part process. One of the largest areas to consider? Bonding. A number of materials can be used to overmold components together, but without a chemical bond or mechanical interlock, some overmolded parts won’t stand the test of time.
This bonding process involves two chemically compatible materials that are molded together to form a strong bond with each other. It’s important to note that not all materials play well with one another.
The compatibility chart below indicate whether a chemical or mechanical bond is recommended for key thermoplastic and thermoset materials.
What happens when your materials are not compatible, the desired bonding strength cannot be achieved, or you want to ensure your materials don’t peel apart from repeated use? This is where designing a mechanical interlock, which physically holds the overmolded material to the substrate, makes sense. There are many ways to design these into parts (see example), so discuss the options with your manufacturer.
If you have further questions regarding rapid overmolding at Proto Labs, contact one of our application engineers at 877.479.3680 or email@example.com.