What is Overmolding?

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Overmolding is an injection molding process used to mold one plastic (commonly a rubber-like plastic called TPE) over top of another component (substrate). The substrate is usually an injection molded plastic part, but various other materials could also be used. Below are a few examples of overmolding applications using TPE:

  • Grip 
  • Vibration Dampening
  • Comfort
  • Sealing
  • Sound Absorption

Adding Grip

Generally speaking, components with handles need something to help the operator maintain grip. Overmolded grips are generally safer for operators because they provide increased grip, especially in wet conditions. Products like garden hose nozzles, cordless drills, kitchen utensils, etc. all use overmolded grips to help the user maintain control of the product. Below is an image of a pistol grip manufactured at Basilius. For this part, our customer wanted to go a step further and add a repeating design detail into the overmolded area. It’s also possible to mold in a logo or add textures.

Overmolded Grip

Vibration Dampening

TPE overmolded mounts and connections can protect or isolate components from vibrations. Using a rubber-like connection between two components can isolate vibrations from mechanical elements like motors and pumps.

Comfort

Since the grip material is injection overmolded, it can be formed in any shape, making it great for ergonomics. It’s possible to shape the overmolded part to form fit nearly anything. You’ve probably seen this on bicycle grips or kitchen utensils. Form-fitting grips not only help with comfort, but can also serve as a stopping point to prevent someone’s hand from moving off the grip.

Sealing

Overmolding can be used to create water-resistant seals on electronics and other devices. The water-tight nature of plastic can be used where traditional seals (like o-rings) are not practical. These seals also allow for custom shape and a permanent connection to the substrate (unlike an o-ring that can fall off). On a larger scale, overmolding can be used for components that need to seal but still remain flexible. An excellent example of this is a shifter boot on a manual transmission car. The shifter needs to move but also prevent water and debris from entering the cabin of the car. In this scenario, a bellows system is often used where the overmolded material is designed to have flexible, layer-like features.

Sound Absorption

Much like vibration dampening, sound waves can be absorbed by overmolding. A good example of this is a motor encased in a plastic case. Overmolding the outside or inside of the case will absorb the motor’s sound, making the device quieter.

For more on overmolding check out this page.

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