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Top 10 Design Tips for Injection Moulding

Designing for Injection Moulding

Designing injection moulded parts is never a simple task. There are so many different factors to weigh up and consider.

The objective is to produce the best quality product or component, and the design will play a fundamental role in whether or not this is ultimately achieved.

For designers, however, there are several other key variables to consider in addition to product quality. These include items such as lead times, cost, and final product application.

Producing the right design will not only help to produce the best quality part, but it will also help to ensure that the manufacturing process is as streamlined as possible, which will mean shortened production cycles, reduced costs, and improved end user experience.

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With this in mind, we’ve put together a list of our top 10 design tips for all designers out there who are looking to design a product for the purposes of injection moulding.

10 Design Tips for Injection Moulding

  1. Design for ease of mouldability: Ensure that the design can be easily moulded and that it does not contain any unnecessarily complex geometries or undercuts. Avoid sharp corners or thin sections that can cause manufacturing issues.
  1. Use draft angles: Incorporate draft angles into your design to allow for easy ejection of the part from the mould. This prevents sticking or damage to the part during demoulding.
  1. Wall thickness: Maintain uniform wall thickness throughout the part to avoid sink marks or warping. Thick sections can take longer to cool, while thin sections can easily break.


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  1. Gate placement: Position the gate (the point at which molten plastic enters the mould) in an area that allows for efficient filling and proper flow through the part. Avoid placing the gate in visible areas to prevent gate marks.
  1. Ribs and gussets: Use ribs and gussets to reinforce the structure of the part. These features improve strength and stiffness without adding excessive material. They also reduce costs and diminish the potential for warping.
  1. Fillets and radii: Incorporate fillets or radii into designs to avoid stress concentrations. These rounded transitions distribute stress evenly, reducing the likelihood of part failure.
  1. Material selection: Choose a material suitable for injection moulding based on its flow properties, shrinkage rate, and mechanical properties. Consult with material suppliers or injection moulding experts for guidance.
  1. Avoid undercuts: Design parts without complex undercuts which may prevent easy demoulding. If undercuts are necessary, consider using mechanical side-actions or slides in the mould.
  1. Consider assembly requirements: If your part requires assembly, design the features in such a manner as to facilitate easy alignment and assembly. Incorporate snap-fit features or mating surfaces for efficient and secure assembling.
  1. Parting line placement: Choose the parting line location carefully, as it will affect the appearance and dimensional accuracy of the final part. Place the parting line in non-critical areas or in hidden locations to minimise its visibility.

Want to Find Out More?

If you’re a designer who’s about to embark on the product development process and you need to speak with a reliable manufacturing partner, we could be the ideal solution for you.

Please contact us for an informal chat and we’d be happy to speak to you about your project.

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