How Overmoulding Enhances Injection Moulding for Better Product Design

If you’re designing a product that needs grip, comfort, or extra protection, overmoulding might be the solution you’re looking for. It’s a process where one material is moulded over another, usually this consists of a soft material over a rigid plastic base.

At Formero, we provide access to Injection Moulding Services, including overmoulding, through our network of trusted manufacturing partners. Whether you’re prototyping or scaling up, we can help manage the entire process and ensure the final parts meet your design and performance needs.

How Does Overmoulding Work?

Overmoulding is a multi-step injection moulding process. It starts with a base component, called the substrate, that is usually moulded from a rigid plastic like ABS, polycarbonate, or nylon. Once that part has cooled, it’s placed into a second mould, where a softer material (often TPE or TPU) is injected over or around it.
The result is a single part made from two materials that are either chemically bonded or mechanically locked together.

Common Applications of Overmoulding

Overmoulding is used across many industries to improve both function and form. Common examples include:

• Consumer goods: Gaming controllers, toothbrushes and headphones.
• Industrial tools: Handles with rubberised surfaces for grip and shock resistance such as hammers and drills.
• Medical devices: Comfortable, ergonomic housings for handheld equipment.
• Automotive components – Functional seals and soft interior touchpoints.

Benefits of Overmoulding

Here’s why designers and engineers often choose overmoulding:

• Improved grip: A soft outer layer (usually TPE) adds traction to otherwise slippery surfaces.
• Comfort: Soft materials reduce pressure points, making tools and wearables easier to hold.
• Impact and vibration resistance: The overmould can absorb shocks and dampen vibration.
• Aesthetic improvements: The look and feel of overmoulded parts can help differentiate your product.
• Sealing and electrical insulation: Overmoulded layers can seal gaps and provide electrical or environmental protection.

By combining different materials, overmoulding can eliminate the need for additional parts or assembly steps with adhesives or fasteners.

Material Selection: What Works Together?

Not all plastics bond well, so material compatibility is a key part of successful overmoulding. At Formero, we work with a wide range of materials and can help you choose the right combination based on your design and performance goals.

Typical combinations include:

The overmould material needs to either chemically bond with the substrate or mechanically lock into it through design features like undercuts or texture.

Design Considerations for Overmoulding

Getting the design right is just as important as choosing the right materials. Here are a few tips to help set your part up for success:

1. Allow for Mechanical Bonding: 
   If the materials don’t chemically bond, you’ll need to rely on mechanical features—like grooves, holes, or undercuts—to hold the overmould in place.
2. Consider Shrinkage:
   Each material shrinks differently as it cools. Proper tooling design is needed to account for this, especially when tight tolerances are required.
3. Use Draft Angles:
   Just like in standard injection moulding, draft angles help parts release cleanly from the mould.
4. Avoid Sharp Corners:
   Rounded corners improve material flow and reduce the risk of stress concentrations or defects during moulding.
5. Plan for Multi-Cavity Moulds (if needed):
   For larger production runs, multi-cavity tools can help keep costs and lead times down—but require careful upfront design.

Is Overmoulding Right for Your Part?

Overmoulding is great when your product needs both form and function. It’s particularly useful if you want to eliminate assembly steps, like gluing or screwing on grips, and instead produce a single, fully integrated part. If you’re aiming for a more refined look and feel, something that feels premium in the hand, overmoulding could be the right solution. It also adds practical benefits like improved durability and resistance to impact, water, or vibration.

Of course, not every part requires overmoulding. But when it’s the right fit, it can have a big impact on both the usability and overall performance of your product.

Get Help with Overmoulding and Injection Moulding

Formero offers access to a wide range of Injection Moulding Services, including overmoulding, through our trusted suppliers. We manage the process from start to finish/ This includes reviewing your part designs, helping with material selection, and ensuring everything is engineered for efficient production.
If you’re considering overmoulding for your next project, we’re here to help.

Injection Moulding, Knowledge Hub