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5 Key Questions to Ask When Considering Reaction Injection Moulding

Reaction injection moulding is a fantastic, albeit niche process. So understanding when to use it and how best to leverage value is important.  We have put together ‘5 Key Questions' to help you determine if reaction injection moulding is the right process for your project, as you start to move your concept from CAD, and into production.

Chances are if you tick a number of these boxes, it’s worth investigating RIM moulding in a little more depth.

  • How many parts do you need each month, each year? If the answer to this question is less than 40 parts per week or 2000 parts each year, then RIM could be an option.

  • How big is your part/product/instrument? RIM moulding is great for parts ranging from handheld right through to a 3M part, so pretty large!

  • What is the value of the end product? With low tooling costs but comparatively higher part costs, it makes more commercial sense to use RIM moulding for higher-value products - +£10K

  • What are your tooling and part budget? Costs vary but if you need low tooling costs to get started, RIM could make sense

  • What is your attitude to risk and long term supply? Do you need the flexibility to make quick and cost-effective modifications, require part traceability and compliance and would like a supply chain that can support life cycles of +10 years?


1. Number of Parts Required?

Reaction injection moulding is ideal when you need 10 off to 2000 off parts each year, delivered in small, regular batches.

RIM moulding is a low volume, manually operated process which offers flexibility in supply and provides the opportunity to have increased complexity due to the associated low tooling costs. This could include collapsible coring for undercut features, over-moulding to encapsulate magnets, keepers and hinge pins and the option to merge a number of smaller parts into one bigger part to save on tooling and part cost.

  • Minimum order quantity - 1 off through to a maximum of 40 parts per week/2000 parts per annum, per tool.
  • Flexible supply to align better with ever-changing market demands, helping to manage cash flow and reduce stock holding.
  • Aim for larger single mouldings with more complexity to reduce tooling costs and assembly time.


2. Size of Parts

The process is capable of producing handheld components through to 3M single mouldings, so the scope of application is significant.

Deep draw parts are possible with minimal draft, with 1m3 parts being typical for the process.

The low-pressure nature of the process means good tolerance control combined with low distortion risk. Making it ideal for complex multi-part assemblies where a range of parts and shapes need to be brought together as a full cladding kit.  Being able to use a single process for a large number of parts simplifies the Bill of Materials (BoM), ensures a colour match between parts and compliance and order management becomes straightforward.

  • Handheld up to 3M mouldings, maximum 30KG in weight.
  • Low distortion risk and consistent tolerance.
  • Tooling costs quite often 1/10th the cost of injection moulding so the bigger the part the better


3. Value of End Product

Reaction injection moulding provides a low-cost tooling route to market but the downside is that piece part costs are inevitably higher.  The cost structure lends itself to high-value items such as medical device equipment, laboratory diagnostics machines or high-end electronics, where batch control, compliance, flexibility in supply and quality finishes are all required.

RIM mouldings are painted in hard-wearing industrial paints, offering a large range of colours and finishes.  UV stability, chemical resistance and EMC shield paint are all options alongside the usual brand enhancement, corporate tie in and the option for multi-colour panels to break up larger surfaces.

  • Traceability and compliance supported by the process
  • Colour matching, multi-colour finishes and flexibility to change part colour batch to batch.
  • Perfect for high value (+£10K) projects where stylish housings are required to protect the complex science and electronics without compromising on material functionality and finish.


4. Budget

RIM moulding offers a stripped back, low-cost tooling process that helps you get to market for a fraction of the cost of other moulding processes.  If you need only a few hundred parts each year, injection moulding tooling costs can be prohibitive.

As a guide, RIM tooling can be as low as 1/10th the price of metal injection mould tooling and due to the stripped-back nature of RIM Tooling, manufacturing time scales are usually very rapid (~ 6-8 weeks).

  • Typically tooling costs range from £5-15K for each part
  • Moulding prices range from £70 up to £700 each depending on size, finish expectations, volumes and any other specific requirements.


5. Risk

Low tooling investment typically in the £1000’s rather than £100K’s, combined with the ease of modifications and speed with which you can design components, means reaction injection moulding can offer you a low-risk manufacturing process.

Making it an ideal process for new innovations, start-up companies and those with limited cash.  Flexible ordering in small batch size means you only buy what you need when you need it and with the option to modify, RIM moulding can be essential for fast-tracking your development phases.

  • No sink, minimal distortion, and quick to design for
  • Small batches combined with the initial low tooling costs all help to remove barriers.


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5 Key Questions to Ask When Considering Reaction Injection Moulding