Plastic Parts - Rapid Prototyping (RP) and Low Volume Production
Injection moulding, the predominant process behind the production of the majority of plastic parts, typically requires long leadtimes and a high degree of confidence in the design. Rapid Prototyping (RP) is ideally suited to handling high component complexity and provides a fast and economic means of validating such designs before tooling release.
As such, there are now an appreciable number of processes available that are able to accurately emulate the geometry of the production component. When combined with a range of different materials designed to simulate production plastics, varying levels of evaluation from limited form and fit, through full functional verification can be performed.
Despite the growth of RP, CNC still plays a significant part in prototyping and low volume production and should not be overlooked as a viable option. Material choices are wider and when combined with global sourcing, the results can be economically attractive.
These and others are covered though the links opposite to assist you in sourcing the most applicable option for your requirement. If you are in any doubt, then please contact Plunkett Associates directly.
Stereolithography
Stereolithography is the most well known of all the RP techniques. Working from a .stl file format it will produce an accurate physical representation of your 3D CAD file for form and fit trials, or subsequent duplication through vacuum casting. A variety of resins emulate various production materials and the parts may be dressed to a high cosmetic finish.
Laser Sintering (or Selective Laser Sintering - SLS)
The major attraction of Laser Sintering is the functionality achieved by the process. Parts are produced in nylon or filled nylon and achieve sufficient strength to allow testing across a reasonable envelope. Using the industry standard .stl file format, parts are typically available in 5 -7 days and can be dressed to achieve a cosmetic finish.
Fused Deposition Modelling (FDM)
The major attraction of FDM is the materials that the process uses. Typically PC or ABS these achieve an acceptable level of functionality. However, the resolution, ability to produce fine detail and surface finish, of the process is not as good as Laser Sintering and as such it is seldom supplied by Plunkett Associates.
Objet
From a prototyping perspective the attraction of Objet is the 16 micron layer thickness that offers a level of finish direct from the machine that other processes cannot yet achieve. However the resins are all acrylate based and do not offer the stability that comes with epoxy Stereolithography resins. That said, the process can offer good flexible parts if timeframes do not permit secondary processes.
Machining (CNC)
Frequently the method of choice until the advent of RP, machining is frequently overlooked. Offering a choice of materials, almost unlimited size and the ultimate in terms of accuracy, it should always be considered. Global sourcing means that machining does not carry a price premium, yet can offer a finish that leaves RP struggling.
Vacuum Casting
Ideally suited to producing a small batch of prototypes where aesthetics are important. Vacuum casting utilises a CNC or RP pattern to create a silicone tool. The flexibility of the silicone not only picks up detail well, but allows the tool to release undercuts and re-entrant shapes without needing loose pieces. Polyurethane (PU) is available in many grades and this is cast into the tool to create the desired component.
Injection Moulding
Usually only considered as a production process, injection moulding will give the production intent material properties and can be economic from as low as 20 pieces. Timescales vary widely, but 2 to 5 weeks would be typical.