Urethane Casting - Silicone Molding

Vacuum casting (also known as urethane casting or silicone moulding) is a manufacturing method that uses silicone moulds to produce plastic parts in a relatively simple way and without the high costs and high lead times required for steel or aluminium moulds.

Urethane casting provides end use plastic parts, both rigid and flexible, with a quality close to the production level. 

Our process of obtaining parts by vacuum casting, built without any expensive and time-consuming tools, always uses a master part made by CNC machining, thus ensuring the finish and quality of the final part.

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Low Production Levels

Polyurethane, PU, parts obtained by vacuum casting are perfect for the production of small quantities – when volumes do not justify investment in injection moulds – as well as for the first series production parts, which can be obtained weeks before the production tools are ready.

Advanced Prototyping – Flexible Parts

Urethane casting process and the relatively inexpensive tools involved make it easy and economical to approximate the design and quality of the parts obtained to production levels. In addition, it is the ideal way to prototype elastomeric parts, with characteristics similar to those of Silicone, TPU, NBR,… and with hardnesses between Shore A 30 and Shore A 90.

Market Testing

A high quality finish makes polyurethane parts ideal for consumer testing, user evaluation and conceptual models. It also allows almost unlimited complexity, including internal corners without radii, unattainable with CNC machining, and designs without demoulding or with uniform wall thickness that cannot be injection moulded.

Parts manufactured and shipped in just



Polyurethane casting can be obtained with both rigid and flexible end use plastics. Urethane parts are generally as strong or harder than injection molded parts, and are significantly stronger than 3D printed parts.


Our vacuum casting process is optimal for low production volumes ranging from a single unit to several hundred pieces. On average, each silicone mould can be cast with a guarantee of around 20 pieces. The maximum quantity will vary depending on the part design.


We offer a wide range of polyurethanes, both soft and flexible -type Silicone, TPU, NBR,... and rigid and resistant -type ABS or PC. In addition, both opaque and transparent parts are available.


Vacuum casting allows pigmented parts to be obtained based on an specific RAL or Pantone code. For this purpose, polyurethane is coloured prior to casting, thus obtaining a coloration equivalent to an injected piece.


Parts obtained by vacuum casting in polyurethane are shipped within 10 working days, depending on the requirements of the pieces and quantities. Injection moulded parts, on the other hand, can take up to a few weeks.

Opaque Elastomer
Waterclear Elastomer


A general-purpose opaque material that simulates ABS thermoplastic. Good for most hardware product enclosures.

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A stiff, transparent material for simulating acrylic (PMMA). Good for see-through applications such as light guides.

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Opaque Elastomer

Simulates all kinds of rubber-like materials such as TPE, TPU, and silicone rubber. Great for wearables, gaskets, and overmolds. Available from Shore 20A to Shore 90A in 10A increments.

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Waterclear Elastomer

Simulates all kinds of rubber-like materials such as TPE, TPU, and silicone rubber. Great for wearables, gaskets, and overmolds. Available from Shore 20A to Shore 90A in 10A increments.

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Vacuum Casting - Silicone Moulding - www.protoandgo.com


The pigment is added to the liquid polyurethane before casting, so each piece has a molded color. Customers can provide RAL or Pantone code for approximate color matching.

Vacuum Casting - Silicone Moulding - www.protoandgo.com


Paint is recommended for parts that require exact color matching. Some very light or metallic colours can only be achieved with subsequent painting. Painting is applied from the RAL or Pantone code supplied by the customer.

Vacuum Casting - Silicone Moulding - www.protoandgo.com


Selecting the pigmented finish is usually obtained with a matt surface, although if you indicate it to us we can study to obtain a gloss finish according to the geometry of the piece and the required color. In the case of a subsequent painting process, a matt, satin or gloss surface finish can be chosen.

Tolerances - Vacuum Casting



0.5 – 6.00 mm

± 0.1 mm

6.00 – 30.00 mm

± 0.20 mm

30.00 – 120.00 mm

± 0.30 mm

120.00 – 400.00 mm

± 0.50 mm

400.00 – 1000.00 mm

± 0.80 mm

Angular: ±0.5º

Vacuum Casting - Silicone Moulding - www.protoandgo.com