Frequently Asked Questions

What to do when the quantities rise?

There are times when the quantities of prototypes required rise well beyond the conventional 1 – 10 type range. This may be due to the type of evaluation that is required, the number of people involved, the fact that the design is still uncertain or that they are really production items! 

Plastic part, CNC machinedMethods can vary but typically the greater the numbers, the closer the prototyping method gets to the production method. 

As quantities rise, the options become more limited and factors such as the geometry and size play a greater role. For example, a small complex part can be laser sintered in significant volumes (100's) at a competitive price. As complexity reduces and size increases, both polyurethane (RIM and vacuum casting) and injection moulding/tooling have a greater role to play. The greater the quantity, the more competitive the tooling options will be over 3D printing or machining.

So, assuming the part is small and an SLS finish is acceptable (i.e. we are more interested in function than aesthetics or the part can be rumbled to improve the finish), SLS is often the place to start.  Similarly high-resolution SLA can be used for small batches of very detailed components requiring specific attributes, such as stiffness, or DMLS used if the part is metallic.

Most often if parts are being made with additive manufacture in production, then they contain features that prevent alternative manufacturing options. For example lattice structures in the core to reduce weight, or they are the combination of several conventional parts fused together. In these cases there is little chance of employing anything apart from the intended production process.Vacuum cast part

CNC machining (computer numerical control) also has a role to play, offering high accuracy and a large range of plastic and metallic materials; small batches can be economically produced. Components can be drip fed from early in the process and design changes can be easily incorporated without the need to alter any tooling.

As quantities rise there are two PU options; the first is Vacuum Casting into silicone tools, the second is Reaction Injection Moulding (RIM) into composite (hard) tools. Whilst requiring tooling, they both have specific attributes that make them attractive to producing quantities of large or complex parts. 

As a general guide, RIM is more applicable to larger, heavier sectioned parts, whilst Vacuum Casting is more applicable to complex, thin walled items. 

To master the complexity, Vacuum Casting utilises a flexible silicone for the tool. This allows the tool to be deformed and the part released, thus avoiding compressible cores and side actions, which would be used in a 'hard' tool.

The limitations are that the silicone progressively hardens, leading to a tool 'life' of around 20 - 30 shots. So 200 parts could therefore require 8 - 10 tools (or cavities) depending on complexity. However these can run in parallel and the parts can be part shipped from about 2 weeks onwards.Low volume injection moulding

Vacuum casting can emulate colour and texture in a variety of grades of polyurethane (PU) resin, both hard and flexible.

Similarly RIM requires tooling, but due to the low pressures employed, facilitates the production of larger parts, without the dramatically increasing price of a similar injection moulding.

We regularly endorse injection moulding as a cost effective solution for quantities down to and even below 100. Offering a range of tooling options; leadtimes can be competitive with vacuum casting and depending on quantities, price can be competitive as well. All with the significant upside of having prototypes in production intent materials.

Development tooling can be economically viable from as low as 50 parts depending on the part in question, and is applicable into the 1000's. Part cost is very low compared to the alternatives, although the tooling is more expensive. Unlike Vacuum Casting, parts cannot be shipped progressively and only start to become available after T1 (first trial). This remains the only way to produce production intent material parts where fillers and material grades are important.

CNC machined metal partsIf the requirement is for metal components, then the options tend to revolve around CNC machining, casting, diecasting, or metal injection moulding (MIM). Frequently the solution is to machine and post process, although casting plays a significant role as well. Die casting and MIM are often excluded due to tooling costs and leadtimes, not always correctly! And now we have metal 3D printing to add to the mix. These processes are applicable across the quantity range depending on material, surface finish, size and geometry. 

In summary, the route chosen needs to be decided upon based on size, complexity, aesthetics, material requirements and time, and the economics become a consequence!

With no vested interest in any one process, we can offer truly impartial guidance on the options, and support you all the way from initial prototypes through design approval/launch to subsequent tooling and production. 

  • “Plunkett Associates have excellent breadth of experience, work with high quality partners and have a flexibility that we have found enables challenges to be met successfully, cost effectively and in a timely manner.”
    Nick Skaer, CEO, Orthox Ltd
  • Plunkett associates always find a solution. Whatever we need to prototype, they have a great grasp on the technologies available, costs and lead-times so we get the right solution tailored to the project needs. Have always delivered and never let us down.
    Naim Audio
  • “I can’t recommend Tim and his team highly enough. We ended up with a design which can be produced and assembled quickly, efficiently and reliably, in volumes that make sense”
    Simon Leggett, Director, Olivewood Technology
  • "Tim's experience, expertise and supplier base have been fundamental to us getting this project off the ground."
    Sam Pearce, Jelly Products Ltd
  • “We were really surprised at how quickly they turned round such a high quality prototype and the parts certainly proved their worth. They were of high enough quality to provide a fantastic visual representation and to undergo rigorous testing."
    Stuart Wilson, Design Director, TRT Lighting
  • “Accuracy, finish and delivery all first class.”
    Andrew Peters, JMDA Ltd
  • “We use Plunkett Associates because we want someone we can trust, that knows what they’re talking about, has all the contacts, will provide reliable advice and feedback and will get the right result for us.”
    Jim Copestick. Design Manager, Thorlux Lighting
  • “We always know exactly what we’re getting and we know we won’t be let down on quality, price or lead times.”
    Mark Williams, Research and Development Director, Johnson Safety Products
  • “Plunkett Associates truly offer a complete turnkey solution with Speed, Effectiveness and Precision.”
    David Harden, Director, Enica Ltd
  • “Kirintec were thrilled with Plunketts. They made a complex process simple and we were just amazed at the lead times achieved. Plus, every single deadline was met without any drama.”
    Penny While, Marketing Director, Kirintec
  • “Thanks to Plunkett Associates flexible, bespoke and cost effective service I was able to produce the objects that I had originally had in mind.”
    Simon Ryder, Artist
  • To create such a consistent quality finish in chrome was an amazing achievement and the prototypes really gave our stand the wow factor.
    James Clark, Group Commercial Director, The Airdri Group
  • Interestingly, people who look at it in its own right with little knowledge of what it does, just like it! It’s tactile and it looks good…
    Tim Collings, Operations Director, Troika Systems Ltd
  • "With their simple to understand language, willingness to go the extra mile and approachability, Plunkett Associates were a great partner for our company. We couldn’t be happier with the results of our project. (A working prototype that they got right first time, by the way). Thank you!"
    Carolina Ballon-Forrester, Director, Kittyrama Ltd
  • Plunkett Associates worked on the design and production of titanium frames for an artificial heart valve where precision and consistency was paramount. Communications were efficient and productive with concepts readily incorporated into the final design, and suggestions for improvements all highly appropriate. The quality of the end product was ideal and I have no doubt that I will use the advice and expertise of Plunkett Associates again.
    David Wheatley, Wheatley Research Ltd
  • “Thanks for the present that arrived this morning, as promised. Parts look first class, as always.”
    Jon Todd, Design Manager, PHS Group
  • “Plunkett Associates have a fantastic supply chain, work with all sorts of production processes and will always do their utmost to solve a problem.”
    Naim Audio
  • “ Plunketts developed a solution that met our precision requirements at a cost significantly lower than alternative manufacturing approaches we had investigated”
    Nick Skaer, CEO, Orthox Ltd
  • “Doing business with you has been an absolute pleasure. You have made my goals a reality. You have been patient, helpful and above all, responsive. Best service that I have experienced in ages. I consider Plunkett Associates to be an integral part of my business plan moving forward.”
    Jet Cooper, Sculptor
Related Processes

CNC Machining

The benefits of CNC parts include substantial flexibility in material choice, high accuracy and repeatability.

more info

Injection Moulding

Produces production intent material properties. Injection Moulding is used for development as well as production parts.

more info

Read more expert articles in our FAQ section where we discuss topics on materials, methods and products.

Back to FAQs
  • “Plunkett Associates have excellent breadth of experience, work with high quality partners and have a flexibility that we have found enables challenges to be met successfully, cost effectively and in a timely manner.”
    Nick Skaer, CEO, Orthox Ltd
    Nick Skaer, CEO, Orthox Ltd
  • Plunkett associates always find a solution. Whatever we need to prototype, they have a great grasp on the technologies available, costs and lead-times so we get the right solution tailored to the project needs. Have always delivered and never let us down.
    Naim Audio
    Naim Audio
  • “I can’t recommend Tim and his team highly enough. We ended up with a design which can be produced and assembled quickly, efficiently and reliably, in volumes that make sense”
    Simon Leggett, Director, Olivewood Technology
    Simon Leggett, Director,  Olivewood Technology
  • "Tim's experience, expertise and supplier base have been fundamental to us getting this project off the ground."
    Sam Pearce, Jelly Products Ltd
    Sam Pearce, Jelly Products Ltd
  • “We were really surprised at how quickly they turned round such a high quality prototype and the parts certainly proved their worth. They were of high enough quality to provide a fantastic visual representation and to undergo rigorous testing."
    Stuart Wilson, Design Director, TRT Lighting
    Stuart Wilson, Design Director, TRT Lighting
  • “Accuracy, finish and delivery all first class.”
    Andrew Peters, JMDA Ltd
    Andrew Peters, JMDA Ltd
  • “We use Plunkett Associates because we want someone we can trust, that knows what they’re talking about, has all the contacts, will provide reliable advice and feedback and will get the right result for us.”
    Jim Copestick. Design Manager, Thorlux Lighting
    Jim Copestick. Design Manager, Thorlux Lighting
  • “We always know exactly what we’re getting and we know we won’t be let down on quality, price or lead times.”
    Mark Williams, Research and Development Director, Johnson Safety Products
    Mark Williams, Research and Development Director, Johnson Safety Products
  • “Plunkett Associates truly offer a complete turnkey solution with Speed, Effectiveness and Precision.”
    David Harden, Director, Enica Ltd
    David Harden, Director, Enica Ltd
  • “Kirintec were thrilled with Plunketts. They made a complex process simple and we were just amazed at the lead times achieved. Plus, every single deadline was met without any drama.”
    Penny While, Marketing Director, Kirintec
    Penny While, Marketing Director, Kirintec
  • “Thanks to Plunkett Associates flexible, bespoke and cost effective service I was able to produce the objects that I had originally had in mind.”
    Simon Ryder, Artist
    Simon Ryder, Artist
  • To create such a consistent quality finish in chrome was an amazing achievement and the prototypes really gave our stand the wow factor.
    James Clark, Group Commercial Director, The Airdri Group
    James Clark, Group Commercial Director, The Airdri Group
  • Interestingly, people who look at it in its own right with little knowledge of what it does, just like it! It’s tactile and it looks good…
    Tim Collings, Operations Director, Troika Systems Ltd
    Tim Collings, Operations Director, Troika Systems Ltd
  • "With their simple to understand language, willingness to go the extra mile and approachability, Plunkett Associates were a great partner for our company. We couldn’t be happier with the results of our project. (A working prototype that they got right first time, by the way). Thank you!"
    Carolina Ballon-Forrester, Director, Kittyrama Ltd
    Carolina Ballon-Forrester, Director, Kittyrama Ltd
  • Plunkett Associates worked on the design and production of titanium frames for an artificial heart valve where precision and consistency was paramount. Communications were efficient and productive with concepts readily incorporated into the final design, and suggestions for improvements all highly appropriate. The quality of the end product was ideal and I have no doubt that I will use the advice and expertise of Plunkett Associates again.
    David Wheatley, Wheatley Research Ltd
    David Wheatley, Wheatley Research Ltd
  • “Thanks for the present that arrived this morning, as promised. Parts look first class, as always.”
    Jon Todd, Design Manager, PHS Group
    Jon Todd, Design Manager, PHS Group
  • “Plunkett Associates have a fantastic supply chain, work with all sorts of production processes and will always do their utmost to solve a problem.”
    Naim Audio
    Naim Audio
  • “ Plunketts developed a solution that met our precision requirements at a cost significantly lower than alternative manufacturing approaches we had investigated”
    Nick Skaer, CEO, Orthox Ltd
    Nick Skaer, CEO, Orthox Ltd
  • “Doing business with you has been an absolute pleasure. You have made my goals a reality. You have been patient, helpful and above all, responsive. Best service that I have experienced in ages. I consider Plunkett Associates to be an integral part of my business plan moving forward.”
    Jet Cooper, Sculptor
    Jet Cooper, Sculptor