Frequently Asked Questions
Development, Prototype and Bridge Tooling - what do I need to know?
Such terms are usually used to refer to injection mould tooling, but are equally relevant to other processes such as metal forming or blow moulding - typically any process where high production tooling costs exist and there is a need for truly representative prototypes.
What are the options?
This type of tooling will usually have lead-times that vary from a few days to 3 - 4 weeks depending on complexity, size and sophistication. Selecting the right option is all about understanding the trade-offs - knowing the strengths of particular manufacturing options, and the capabilities of individual suppliers.
Typically, these processes will seek to automate, standardise and minimise queuing time to achieve the delivery. Thus, achieving a good fit between the requirement and the suppliers' process is critical.
Equally important is freezing the design prior to commencing the tooling. None of these processes take kindly to design changes and, if these become necessary, can frequently cause the entire manufacturing cycle to be restarted.
A wide variety of materials are used
A wide variety of materials are used, from SLA resins such as Nanotool, to epoxies, aluminium and steel. Selecting the material is dependent upon knowing the quantities of parts, the moulding material and any potential run-on requirements. Long gone are the days when tooling was made from steel… end of story!
Standardisation has led to some processes just manufacturing the tooling inserts and the bolsters being fully standardised. This has the effect that the client never owns the tool and is unable to relocate the moulding should this be required. However it does have beneficial effects on the tooling cost, but is normally associated with much higher moulding prices, which is acceptable if quantities remain low.
With easy access to China, the naturally assumed logic of cost relating to tool capability has also been removed. Toolmaking generally retains a high labour content, and as such the lower cost economies are able to deliver high quality steel tooling at very competitive price points.
Accessing these options requires a clear vision of the requirement. Being able to answer the following will certainly help.
What do I need to know?
Quantity: How many are needed and what is the potential for a follow-on requirement?
Time: When will data be available and when will the parts be required for initial and follow on batches?
Material: Is the injection-moulded material really required? If RP or PU parts will suffice there is a high chance these routes will be cheaper. Is the material commercially available worldwide, or can a generic substitute be used?
Geometry: Has the part been designed with injection moulding in mind? Is it drafted? Is it straight 'open and close' or are there side actions? If quantities are low, is it acceptable to create some features through a post-moulding operation or the use of loose inserts within the tooling?
Tolerances: Is the part open tolerance or extremely critical? Remember, CAD files do not contain tolerances and these need to be supplied early as a drawing. Blanket tolerances and minimising tight limits will benefit both lead-time and cost.
Aesthetics: What kind of finish is required? Are the parts purely functional or will textures be needed? Can the textures be added after T1 and after the initial parts are delivered? Is colour important and will the material need a master-batch?
Commercial: Tooling will almost certainly require upfront payments of up to 50% of the tooling price. Can this be processed without undue delay? In the case of Far Eastern tooling, this deposit needs to reach the supplier before the clock is deemed to start. Is tool ownership important, or is this a piece part requirement? (Some companies have very strict rules for buying tooling and the way in which it is amortised).
Tool type: Is this a development tool (short life), low volume production or production requirement?
Whilst this is not exclusive, it will certainly help in optimising the solution. Remember the more flexible the requirement, the faster parts can usually be produced, and hence the desire to differentiate between production and development tooling.
When do I move to development tooling?
Like all prototyping techniques, this is about risk management. To be considering development tooling, parts will have already been through SLA, SLS or FDM so the form and fit issues of the design will have been addressed.
Classic reasons for development tooling therefore include:
· The need for several hundred parts for accelerated testing
· Concerns about the way in which a particular plastic will perform in real conditions
· Whether a part is mouldable and assessment of stress
· The need to understand light transmission in complex light pipe geometries
· Filling an interim requirement due to production tool slippage
· Fulfilling a low volume production requirement
· And on (very) rare occasions, it could be the only way to manufacture the part!
Whatever your reasons for considering this, talk to us for a full appraisal of your options and costed proposals to move forward.
Selective Laser Sintering (SLS)
Selective Laser Sintering (SLS) is the second most commonly used process after Stereolithography (SLA). SLS parts can be produced with high functionality in very short lead times.
Produces production intent material properties. Injection Moulding is used for development as well as production parts.
Produces accurate 3D models with a range of material choices. High Res SLA and Micro SLA for smaller parts.
Read more expert articles in our FAQ section where we discuss topics on materials, methods and products.
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