Subscribe to our newsletter to receive the latest news and events from TWI:

Subscribe >
Skip to content

What is rapid prototyping?

   

Rapid prototyping is the fast fabrication of a physical part, model or assembly using 3D computer aided design.

The design is then often created using 3D printing / additive manufacturing. Where the design closely matches the proposed finished product it is said to be a high fidelity prototype, as opposed to a low fidelity prototype, where there is a marked difference between the prototype and the final product.

How Does it Work?

Rapid prototyping (RP) includes a variety of technologies, although most utilise layered additive manufacturing. However, other technologies used for rapid prototyping include high-speed machining, casting, moulding and extruding.

While additive manufacturing is the most common process for rapid prototyping, other more conventional processes can also be used to create prototypes.

These processes include:

  • Subtractive - whereby a block of material is carved to produce the desired shape using milling, grinding or turning.
  • Compressive - whereby a semi-solid or liquid material is forced into the desired shape before being solidified, such as with casting or moulding.

Common Rapid Prototyping Types

  1. Stereolithography (SLA)

    This fast and affordable technique was the first successful method of commercial 3D printing. It uses a bath of photosensitive liquid which is solidified layer-by-layer using a computer-controlled UV light.

  2. Selective Laser Sintering (SLS)

    Used for both metal and plastic prototyping, SLS uses powder bed fusion to build a prototype one layer at a time using a laser to sinter the powdered material. However, the strength of the parts are not as good as with SLA, while the surface of the finished product is usually rough and may require secondary work to finish it.

  3. Fused Deposition Modelling (FDM)

    This inexpensive, easy-to-use process can be found in most non-industrial desktop 3D printing. It uses a spool of plastic filament which is melted inside a printing nozzle barrel before the resulting hot liquid resin is laid down layer-by-layer according to a computer cutting program. While the results generally have a poor resolution and are weak, this process is fast and cheap, making it ideal for product development.

  4. Selective Laser Melting (SLM)

    Favoured for making high-strength, complex parts, Selective Laser Melting is frequently used by the aerospace, automotive, defence and medical industries. This powder bed based fusion process uses a fine metal powder which is welded and built into the prototype using a high-powered laser. Common SLM materials used in rapid prototyping include titanium, stainless steel and cobalt chrome.

  5. Laminated Object Manufacturing (LOM)

    This inexpensive process is less sophisticated than SLM or SLS, but it does not require specially controlled conditions. LOM builds up a series of thin laminates that have been cut with laser beams or another cutting device to create the CAD pattern design. Each layer is delivered and glued in top of the previous one until the part is complete.

  6. Digital Light Processing (DLP)

    Similar to SLA printing, this technique also uses the polymerisation of resins which are cured using a more conventional light source than with SLA. While faster and cheaper than SLA, LOM often requires the use of support structures and post-build curing.

    An alternative version of this is Continuous Liquid Interface Production (CLIP), whereby the part is continuously pulled from a vat, without the use of layers. As the part is pulled from the vat it crosses a light barrier that alters its configuration to create the desired cross-sectional pattern on the plastic.

  7. Binder Jetting

    This technique allows for many parts to be printed at one time, although the parts produced are not as strong as those created using SLS. Still under development, Binder Jetting takes a print bed covered in metal powder onto which hundreds of nozzles spray micro-fine droplets of liquid binder.

    Each layer is then compacted by a roller before the next layer of powder is laid down and the process begins again. Once each layer is built the part is cured in an oven to burn off the binding resin and fuse and solidify the metal powder.

Applications of Rapid Prototyping

Product designers use this process for rapid manufacturing of prototype parts. This can aid design and development of the manufacturing process ahead of mass production.

Originally, this was primarily used to create parts and scale models for the automotive industry although it has since been taken up by other industries such as medical and aerospace.

Rapid tooling is another application of rapid prototyping, whereby a part, such as an injection mould part, is made and used as a tool in another manufacturing process.

What are the Advantages of Rapid Prototyping?

There are a number of rapid prototyping advantages, such as being able to gain a more complete picture of how a product will perform in the early stage of the design cycle, allowing changes to be implemented earlier in the process. The time this takes can vary from a few days to a number of months, depending on the methods used.

How Much Does it Cost?

The cost of rapid prototyping depends on a number of factors, including volumesize of the part or parts being created, the finish, the materials used and how much cleaning is required.

Rapid Prototyping Services

TWI has world leading experience and expertise in 3D printer technologies / additive manufacturing processes. We can also assist with prototyping.

For more information please email:


contactus@twi.co.uk