Have you ever wondered how these items were made??

Injection Molding Design Tips - Overmolding - Screwdrivers
The answer is overmolding. The overmolding process involves the use of two separate materials to form one cohesive component. The most common type of overmolding is insert molding. Insert overmolding is an injection molding process where one material (usually elastomeric) is molded “over” a secondary “substrate” material (usually a rigid plastic or object).

Overmolding can add immeasurable value to product design by enhancing the end users experience in terms of comfort, ergonomics, and ease of use. In order to achieve this level of manufacturing there are two important concepts that must be understood for success to take place:

1) Know your materials

The materials used need to be compatible so that your designs attain a high level of molecular adhesion. Know what the melt temperature is of your substrate and overmold. If the melt temperature is lower on your substrate than your overmold material, then you are in for a big problem! Also, if you are using color, make sure your color concentrate is compatible with your other materials and won’t degrade their properties. Using the right materials could make or break your designs.

2) Understand your designs

When designing, you need to consider how much or how little you want your substrate and overmold to stick. Don’t count on the material alone to create the adhesion that you want. To ensure that the components “mesh” well with one another, use mechanical interlocks such as these:

Injection Molding Design Tips - Overmolding

Knowing the proper rules for overmolding can yield a very successful and aesthetically pleasing product. To discuss overmolding options for your next project or any other injection molding information, please send us an email or give us a call at (770) 901-3200.