Polyurethane Casting

PU casting is also known as silicone rubber casting, or Room Temperature Vulcanization (RTV) casting. The mold material is silicone rubber and the cast material is PU.

The pattern for the mold is normally made by 3D printing or machining. One silicone rubber mold can cast 25-50 pieces of PU parts. The PU material consists of two parts in liquid form.

When the two parts are mixed and cast in a silicone rubber mold, they solidify. In silicone rubber mold casting, the PU takes from one to two hours to cure. The cost of a silicone mold is usually several times higher in unit price compared to the cast, but this is normally factored into the unit price of the cast itself. The PU casting method is preferred over the machining method in following scenarios:

  • Lower the unit part cost when the volume goes higher;
  • Make complex shapes that are not feasible by machining;
  • Have special material requirements, such as transparency.

The PU casting process is ideal for low volume plastic parts. It saves clients from expensive and long lead-time production tooling. Also, PU casting allows certain complex shapes that are not attainable by injection molding because the silicone rubber mold is soft to allow large deformation to release the cast from the mold itself.

Silicone rubber mold for the Control Box, for Nytric Ltd.

The above picture shows the mold and the cast. The part has a large special undercut that cannot be done by injection molding.

Our expertise

PU casting is a tricky process, and is difficult for many other companies to handle. After eight years of exploration, innovation and discovery, we have developed our very own techniques. By applying those techniques, we have successfully overcome the three biggest obstacles of PU casting: voids, deformation and large tolerance. Our failure rate is one in ten, far exceeding the industry standard failure rate of one to three. This enables us to bring the cost down dramatically while providing clients with about half of the market price, with tolerance close to injection molded parts.

The baseball is clearly visible from 2 layers of the Light-pipes for the boarding-pass kiosk, United Airlines. One is 50 cm long and the other is 60 cm long.

We fabricated this 9 mm thick light-pipes which span over 0.6 meters. The pieces have no voids, no sink, and is over 92% transparent. Very few companies can do such quality part.

Cast housings for Amera WiFi Dome, for Cognitive Systems

MYO wrist band (85 degree Shore A hardness rubber), made for Thalmic Labs


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Polyurethane (PU)

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  • 7895 Tranmere Dr., Unit 13,
    Mississauga, ON L5S 1V9, Canada

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