Overmoulding has emerged as a crucial technique in the dynamic manufacturing world within plastic injection moulding. It offers enhanced functionality, improved aesthetics, and added value to plastic products, making it a favoured choice across various industries. This blog explores the concept of overmoulding, its benefits, applications, and the process involved.
Overmoulding, also known as multi-shot moulding or two-shot moulding, is a sophisticated injection moulding process in which two or more materials are combined to form a single, unified product. This technique involves injecting a secondary material over a substrate or base material, creating a seamless bond between the different materials. The primary goal of overmoulding is to leverage the properties of multiple materials to enhance the performance and aesthetics of the final product.
There are several key steps to overmoulding, here, we will follow the production process for one of the many parts we produce at PNP:
1. Substrate Moulding: The process begins with the injection moulding of ABS as a base material. This material gives the final component the rigidity it needs for its intended use.
2. Cooling and Secondary Operations: Once the component is moulded, it is given time to cool down before secondary operations take place. To be held inside the cavity when being overmoulded, the part needs to be reamed and de-burred.
3. Secondary Material Injection: The base component is placed into a second mould cavity and TPE is injected over the base material, this bonds to form a cohesive, rigid and multi-material component.
4. Cooling and Final Inspection: The combined component is closely inspected to check the integrity of the bond and remove any excess material before being left to cool. The completed component is packed ready to be used in a conveyor belt assembly for the coffee machine industry.
Benefits of Overmoulding
Overmoulding, with its ability to enhance functionality, improve aesthetics, and add value to plastic products, offers numerous advantages, making it a preferred technique in various industries. This blog will explore these benefits in detail.
Enhanced Functionality: By combining different materials, over-moulding can enhance a product's functionality. For example, a rigid plastic handle over-moulded with a soft, rubbery material provides a comfortable grip.
Improved Aesthetics: Overmoulding allows for creating products with visually appealing, multi-coloured, or multi-textured surfaces. This is particularly valuable in consumer goods, where appearance is key.
Cost Efficiency: The overmoulding process can reduce assembly costs by eliminating the need for separate components and additional assembly steps, resulting in a more streamlined production process.
Increased Durability: The bonding of different materials can improve the durability and longevity of the final product. For instance, a rigid component overmoulded with a shock-absorbing material can better withstand impact.
Design Flexibility: Overmoulding offers designers greater flexibility in creating innovative and complex products. Combining materials with different properties opens up new possibilities for product design.
Examples of Overmoulding at PNP
1. Power Tools: We use a moulded bearing housing to house a set of bearings, complete with spacer. This housing is used as an insert in the tool to mould into the final product.
2. Education: We produce rubber feet from TPE to combine with polypropylene to mould our Wedge Whiteboards A frame, this helps to prevent the product from sliding around and helps to protect the corners from damage.
3. Dentistry Devices: Firstly, we mould the ‘pivot’, this insert is placed inside the tool and EVA is moulded around it. The use of the two materials is key to the function of the component which will be used by dentists as jaw aligners.
Conclusion
Overmoulding in plastic injection moulding is a versatile and powerful technique that enhances product functionality, aesthetics, and durability. By combining multiple materials into a cohesive product, manufacturers can create innovative solutions that meet the evolving demands of various industries.
If your product involves overmoulding or is low volume (below 5k units), call us now on 01453 833 388. At PNP, we are ready to take your project beyond the basics and into exceptional manufacturing. Contact us today to explore how we can meet your specific needs and exceed your expectations.
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