Techniques for obtaining a rapid prototype

There are several technologies for designing parts with rapid prototyping. They can be divided into three groups. The first includes additive technologies, the second includes so-called subtractive techniques and the final category is low-pressure injection.

Additive techniques

They represent a process for producing a part by addition of material (in liquid, powder or wire form), by successively stacking layers one on top of the other. The latter are solidified by a physical or chemical process (laser, light, strong heat, etc.). They are opposed to subtractive techniques that work by removing material.

Below are the principal additive technologies:

  • Stereolithography or SLA: This technology works by adding epoxy resin, an equivalent material. The part is then polymerised by means of UV light to solidify it.
  • Fused deposition modelling or FDM: The plastic material is deposited in the form of wire through a nozzle.
  • Powder sintering: Layers of powder are successively added and solidified. This technique also uses an equivalent material.
  • Selective laser sintering or SLS: The material in powder form is placed in a tray. A laser is used to sinter and solidify the part.
  • 3D printing: A machine deposits resin on a tray layer by layer. The material is subsequently solidified.

Subtractive techniques: CNC machining

CNC machining, also called digital milling, works by removing material. A computerised milling machine mills a block of material to shape the plastic parts. This process has the advantage of using the right material. The characteristics of the parts are thus very close to reality.

Low-pressure injection: Silicone moulding

Vacuum duplication works by injecting a liquid material, polyurethane (PU), into a silicone mould. The impression of this mould corresponds to the shape of the part to be produced. The many types of PU available make it possible to get as close as possible to the right materials. Thus, the parts are very similar to series parts. In addition, the cost and speed of production of vacuum casting make it the most relevant technology for small series.

In conclusion: Additive technologies are used primarily for projects with no functional or visual requirements. They are useful for visualising a part. Conversely, CNC machining makes it possible to design prototypes that are very close to reality mechanically and visually. This process of removing material is suitable for quantities not exceeding ten parts. Beyond this, vacuum duplication is recommended because it allows economies of scale and saves a great deal of time. Also discover the difference between 3D printing and rapid prototyping.

If you are in doubt about the most appropriate technology for your project, do not hesitate to contact us by e-mail, or send us a request directly on our quote request page.

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