Bridge Tooling – What is it and When Should I Use it?

Bridge Tooling can also be known as development tooling or rapid tooling, and defines a stage in development where there is a need for moulded parts but production tooling is unavailable. Its name coming from the fact that it forms a bridge between prototyping and production.

When is bridge tooling used?

The requirement can be driven by a number of issues, for example:

• The production intent material is a ‘must have’ for evaluation purposes
• The quantity of parts required makes prototyping uneconomic
• A trial batch is required ahead of production release
• The design is not sufficiently stable to allow production tooling
• Initial part call off is too low to warrant production tooling manufacture

Bridging the Gap

The process can also be used to ‘bridge the gap’ with motive originating from time saved, early availability of parts or cashflow. Often on new projects, the quantities are far from certain, making justification of tooling spend difficult. Bridge tooling allows that ‘toe in the water’ usually as a single cavity, that allows the production tooling spend to be deferred and the market evaluated. In some instances the development department has even managed to ‘sell’ their tooling to production recouping their budget and providing availability on zero lead time!

Aluminium as opposed to steel

Aluminium is frequently the material of choice for bridge tooling as it permits faster machining, offers very good thermal conductivity and can be worked/handled easily. (See our article, “Should aluminium be considered as a tooling material?”)

When combined with standard mould frames and loose inserts this all helps to get a mould into a moulding press faster, usually a major requirement to tooling of this type. The loose insert approach can also help with forming threads or difficult undercuts if the quantities are low enough. Whilst this is to the detriment of the moulding cycle time, it allows moulding to commence earlier.

The result is a mould tool that costs less than a production tool, can be up and running in two to three weeks, and has the capability to produce from ten to a few thousand parts. Whilst the individual unit cost may be higher than full production parts, batches of hundreds of parts may be completed faster than if conventional production tooling was used for the same quantity.

An ideal solution for smaller quantities of production parts

Plunkett Associates uses bridge tooling for all of the reasons mentioned above. The standardisation of the process allows this tooling to be available at a price point that makes it an ideal solution when smaller quantities of production parts are required.

The advantages of injection moulding go beyond just the material options available; the consistency of product quality is extremely high and the appearance and feel of the product implies a high volume, high value item.

The challenge has always been to bring these advantages to low volumes without making the economics unattractive. Bridge tooling gives this opportunity and Plunkett Associates is injection moulding from quantities as low as 50 parts.

Selecting the right process

Whether bridge tooling is an option for you will depend on quantities, part complexity and time available. Selecting the right process is all about understanding the trade-offs, knowing the strengths of particular manufacturing options and ensuring the design is suitable for the selected process.

We can help assess your required material, part geometry and tolerances, and design a bridge tool and assess the unit costs. If you have a requirement for a minimal quantity production ready parts, then talk to us today about bridge tooling.

Plunkett Associates
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