Vacuum Casting | Rapid Prototyping | Low Volume Manufacturing

Our company will help You manufacture High-End prototype and a small amount of your unique product

Vacuum Casting
(Silicone & Resin Casting)

The technique of casting polyurethane resin elements in silicone moulds is used to produce functional plastic prototypes or final products in small quantities.

HIGH-QUALITY SURFACE

STIFF MATERIALS

ANY COLOUR

COMPLEX SHAPES

TRANSPARENT PARTS

RUBER PARTS

Small series manufacturing (3 – 1000  parts)

Imitation of the final product at exhibitions, presentations and marketing materials

Product testing before the launch: mechanical strength, appearance, shape

Advantages

  • High-quality surface texture
  • Quick delivery
  • Complex shapes
  • Any colour according to the RAL palette
  • Fully transparent castings
  • Stiff materials

Limitations

  • Mould life 20-30 castings
  • With large amount of castings, the appropriate number of moulds is made
  • Maximum temperatures up to 80-90 C
  • Maximum size 450 x 350 x 270 mm
  • Minimum element wall width – 1-1.3mm
  • The smallest size – about 1 x 5 x 5 mm

Process

  1. Accepting 3D file (.stl or .step)
  2. Manufacturing of master-model
    1. SLA 3D printing 
    2. Adjustment of 3D printing surface
    3. Applying surface texture or polishing)
  3. Mould manufacturing
    1. Master-model is immersed in a two-component silicone
    2. Curing silicone
    3. Cutting the mould and removing the master-model 4. Hardening form)
  4. Casting parts from a polyurethane resin
  5. Final treatment
  6. Quality control

Materials

We are using the two-component polyurethanes for a vacuum casting. Material colour is achieved by adding specific pigments to a resin.

Exemplary materials

  • Simulation of ABS, PVC, PP etc.
  • Elastomers – Shore 30-90A
  • Transparent
  • Non-flammable – FAR25
  • Food contact – Approved for contact with dry food 

Master model and surface structure

A master-model is required to produce the silicone mould. The look of the finished product and precision of a geometry depends on master-models accuracy.

Initially, the master-model is printed with SLA technology (stereolithography), over the next stages the surface is sanded to remove 3D printing traces and to level the surface. The surface structure is then applied by spraying or polishing. For uniform surfaces, structured films can be used.

For greater accuracy, it is recommended to mill the model (if the shape allows).

The master model can also be provided by the customer.

Material dimensional tolerances

  • Simulation of ABS, transparent and aviation: 0.4 – 0.6%
  • Food / medical: 0.3 – 0.5%
  • Non-flammable: 0.5 – 0.7%
  • Prototype / decorative (poor resistance parameters) 0.3%

Element minimal thickness tolerances: +- 0.1-0.2mm (depending on the object shape)

What affects tolerances

  • Heating up the mould increases the cast element by 0,1-0,2%
  • Dimensional tolerances of SLA printing: +- 0.1-0.2%
  • Sanding and applying new textures to surfaces can change
    element’s sides thickness by 0.1-0.3mm
  • The tolerance is affected by the type of silicone  & polyurethane used

Precision castings

  • Master-model CNC milling recommended
  • Special silicones with higher accuracy are used to make moulds
  • With precision castings, moulds life cycle is reduced to
    12-17 castings, and the dimensions of each casted element
    are checked.

Silicone mould, manufacturing process

  1. Attaching foil to the master-model’s edges to determine the dividing line of the mould*
  2. Adding filler and venting channels to the master-model, which will later be used to cast the resin
  3. Install the master-model into a container adjusted to its size & casting two-component silicone
  4. Curing silicone
  5. Cutting the mould into two pieces and removing the master-model
  6. Final curing of the mould at high temperature

* Thickness of the dividing foil: 0.15mm. The foil is usually attached to the edges of the master-model. Casting element’s edge height increases by the thickness of the foil. In cases where given dimension is important, it is recommended to reduce the edge height in the design.

Polished surface

  • To obtain the glossy surface of the casting element, the master model (SLA or CNC) is polished.
  • High gloss elements are additionally polished after casting.
  • The quality of polished surfaces can be limited by the shape or master-model manufacturing technique.

Transparent elements

The colour of the transparent element and the level of transparency can be adjusted by adding pigments.

Threads

  • threads can be moulded
  • steel threaded inserts can be glued into the element

Inquiry form

Before sending a request for a quotation, please answer the following questions:  

  1. STEP or STL file
  2. Dimensional tolerances (without this information, production prices are calculated considering dimensional tolerances of +/- 0.6 – 0.7%, (minimum +/- 0.2 mm) and wall thickness +/- 0.15 – 0.25 mm, if project requires greater accuracy, please specify.)
  3. Surface texture of the element and which sides need to be surface finished (Where 3D print layers may be left)
  4. Colour
  5. Quantity
  6. Material parameters or in what conditions and environment the element will be used (temperatures, hardness, impact and bending resistance, UV resistance, etc.)
  7. Expected delivery date & deadline
  8. Other details (threads, painting, tightness of the housing, gaskets, and other additional information)

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