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Urethane Casting / Polyurethane Casting, Urethane Molding / Polyurethane Molding and Urethane Mold Making


Urethane bellows for use on industrial machineryProtoCAM offers urethane casting and urethane mold making for short-run production. There are many urethane casting materials, making urethane molding ideal when your production material is going to be a plastic injection molded resin. After your stereolithography (SLA) prototype has design has been approved, the SLA part can be prepared for use as a molding pattern. Urethane molding is another phrase to describe Room Temperature Vulcanization (RTV) molding. Urethane is the commonly used shortened form of polyurethane, so urethane casting is the same process as polyurethane casting, urethane molding is the same process as polyurethane molding, and urethane castings are the same items as polyurethane moldings.

Urethane Casting Process
To start the mold making process, a master pattern is needed; it can be a part you supply, or a stereolithography prototype that has been given a "finishes" Level 4 finish. The master pattern is coated in a silicone-based liquid rubber. Once the liquid hardens, the master pattern is removed, and the void left behind is injected with a urethane casting material that best fits your material requirements. Using this process, several copies, or urethane castings, can be made of the initial prototype.

Download an animated video demonstrating the Urethane casting / RTV mold making process.

Key Benefits

  • Fast turn-around (up to several parts per shift)
  • High degree of accuracy is maintained in the copy, including surface finish
  • Parts without draft, or with undercuts, can be reproduced
  • Different materials can be used for each casting, making it possible to test your design with a variety of material properties

Urethane Casting Materials

  • Liquid silicone rubber
  • Urethane / polyurethane

Urethane Casting FAQ

What materials can ProtoCAM cast?
Please let us know the production thermoplastic for your part and we will pick the urethane / polyurethane that most closely matches its mechanical properties.
How large a part can you mold?
Virtually any size. Through cutting and gluing, stereolithography master patterns can be made that exceed the size of any single SLA machine. In this manner, ProtoCAM has successfully molded parts over 3' x 3' x 3' in size.
What colors can be created?
ProtoCAM can exactly match any color using a swatch or paint identification number. The lead time for an exact color match is three weeks; however, ProtoCAM can approximate colors with no additional lead time.
Can urethane castings be painted?
Yes, ProtoCAM recommends painting the parts after over-curing the part in a specific color. This will yield a better quality part finish.
What type of surface finish can a part have?
The common finishes are gloss, textured and matte.
What temperatures can urethanes withstand?
There is no standard answer to this question. Urethane casting materials have individual heat deflection temperatures, the maximum of which is 340°F. ProtoCAM has experience in fire-retardant urethane casting materials.
Can ProtoCAM produce prototypes with living hinges?
Yes, please contact our sales team for specifics.
How many parts can be produced per day?
A single cavity mold can be "shot" from 1 to 3 times per day, depending on material selection. (The phrase "shoot a mold" refers to the pouring of urethane into an empty mold.) If you need castings more quickly, a multiple cavity urethane mold can be produced. The number of cavities in a single mold depends greatly on the part complexity and size, with 10 being a reasonable upper limit.

Post curing a urethane casting, and thereby strengthening it, will also reduce the number of castings that can be produced per day.
How does a urethane casting cost?
Piece price varies from project to project depending on the size and complexity of the part, as well as the number of castings. Many parts start as low as $19 per piece, but please contact us for an exact quote.
How much does a Urethane casting / RTV mold cost?
The price for RTV molds varies depending on part complexity and size, but typical molds start as low as $395. Please contact us for the cost for your design.
How long after I order are urethane molds retained?
ProtoCAM retains molds for a year. If you plan to order additional pieces off of an existing mold after a year, please let us know.
How many castings can I expect to receive out of a mold?
Typically, around 15-25 shots. This figure depends on the part size, complexity, and material selection. For very complex molds expect 10-15 shots; while for simple molds expect 30-50 shots.
How accurate are urethane molds?
As accurate as the stereolithography prototype (+/-0.005"); however, tolerances of +/-0.002" have been achieved.
Can you produce wax castings?
Yes, we use the urethane mold making process to produce a mold suitable for wax castings. Such castings are ideal for use as investment patterns for metal casting. Care must be taken to produce the master pattern with the appropriate shrink factor for the target metal. Please contact us for a quote.
Can you produce castings out of silicone rubber?
Yes. We have low durometer urethanes that can be very soft, but we can also make stereolithography molds and inject silicone rubber into it. Please contact us for additional details, and we will be happy to provide you a quote.

Contact ProtoCAM for Urethane Castings / Urethane Mold Making

Please contact us to discuss your urethane casting and urethane mold making needs or to request a quotation.