ProtoCAM: Additive Manufacturing, 3D Printing and Rapid Prototyping.

Urethane Casting

In urethane casting (also called urethane molding, RTV molding, or RTV mold making), a liquid material is poured into a mold containing a hollow cavity in the shape of the part, then allowed to solidify. The technique allows for the creation of small quantities of production-ready parts without the added expense of machine tooling.

Our Urethane Casting Work

About Urethane Casting

Urethane casting (or polyurethane casting) is ideal for additive manufacturing short-run production of pieces made from a plastic injection-molded resin. Often performed after an RTV mold (also called a room temperature vulcanization mold) is made from a stereolithography (SLA) prototype, urethane casting is a cost-effective way to reproduce production-ready parts in small quantities.

After a mold is created, urethane casting material – synonymous with polyurethane casting material – is injected into the mold’s “void.” This allows for near-perfect copies of the original prototype to be created. We have low durometer urethanes that can be very soft, but we can also make stereolithography molds and inject silicone rubber into it.

Steps For Creating a Urethane Casting

  1. Risers are put on the part to allow air to escape from the final mold
  2. A thin film is attached to the part, which will act as a seam for the final mold
  3. A box is built around the entire structure, and it is filled with silicone rubber
  4. Once the silicone rubber has cured, the box and risers are removed, the mold is opened at its seam, and the original part is removed
  5. The mold is ready for use and any type of urethane can now be injected into the mold to create an exact duplicate of the original

Watch Urethane Casting in Action

Why Choose Urethane Casting


A high degree of accuracy is maintained in the copy – including the surface finish.


Parts without draft, or with undercuts, can be reproduced. Likewise, different materials can be used with the same mold, making it possible to test designs with a variety of material properties.


Several parts can be created per shift once the mold is complete.

Typical Urethane Casting Use Cases

Small-batch manufacturing Engineering design verification Alpha and beta builds
Pre-production parts Functional prototypes