Urethane casting is most commonly used during the prototyping process and can generally be expected to hold +/- .010″ tolerances with +/-0.003 in/in (whichever is greater). For urethane casting equipment and parts with tight tolerance requirements, Fathom generally recommends CNC machining or injection molding. Regarding soft parts, there is a Shore A tolerance of +/-10. Please note, the above tolerances are not guaranteed because geometries vary and every application is different, so please speak directly with one of our urethane casting experts.
|Soft Tool Casting||Requires a master pattern & a silicone tool be made.|
|Master Patterns||Usually CNC machined master patterns can last up to one year for most geometries, though masters can break during the making of the silicone tool. 3D printed (e.g. PolyJet or SLA) masters have a shorter shelf life. Masters are destroyed after their useful life.|
|3D Printed Tools||Tools are good for up to 20 parts for most geometries & can deliver quality parts up to 90 days from being made—tools are destroyed after their useful life.|
|Overmold||Complex parts such as overmolds can be achieved, however, the urethane casting process does not result in a very strong chemical bond between shots, regardless of material selection. Parts should be designed to maximize mechanical bonding between shots.|
|Color||Parts can be casted in color & will approximately match specified Pantone color, however, paint is recommended for show models (greater cosmetic result) that require exact Pantone color matching.|
The urethane casting process is as follows:
The process enables designers and engineers to get production-like urethane casting material parts in their hands quickly, whether a company is in the midst of the prototyping phase of product development or in need of finished looking parts for final tests and presentations. We currently offer the materials listed here. If you need any assistance selecting the proper material for your project, please do not hesitate to contact us.
|RIGID MATERIALS||SHORE VALUE||COLOR OPTIONS||NOTES||RECOMMENDED PRODUCTION METHOD AFTER PROTOTYPING|
|ABS-Like||85 D||Can Be Colored for Near Match to Pantone||Common Material Choice||Cast Urethane Injection Molding|
|UL94V0 Rated||74 D||UL94V0 Rated Material Meets Specified Flammability Standard|
|High Temp||80 D||Light Tints are Very Difficult as Resin Is Naturally an Off White||Glass Transition (Tg) at Over 120°C|
|Clear High Temp||87 D||Clear Only||Requires a High Polish to Achieve Water Clear Finish, Glass Transition (Tg) at 110°C|
|SOFT MATERIALS||SHORE VALUE||COLOR OPTIONS||NOTES||RECOMMENDED PRODUCTION METHOD AFTER PROTOTYPING|
|Silicone||30A-50A||Can be Colored for Near Match to Pantone||Cannot Paint, Food Grade||Compression Molding or Liquid Silicone Injection Molding. Increased Range of Shore Values are Possible. Talk to an Expert Directly to Learn More.|
|Rubber-Like||30A-90A||Cannot Paint||Injection Molding, Compression Molding or Liquid Silicone Injection Molding|
|Clear Rubber-Like||30A-80A||Clear, Can be Tinted to Achieve Transparency||Clear, Cannot be Painted|
Additional Notes // If color matching needs to be exact, Fathom often recommends doing a first article even though it will extend the timeline. If a color or assembly match needs to be made for other parts, a sample part is recommended to confirm color match. Parts can be molded in glossy or matte finish—please always specify. If Shore A needs to be exact, Fathom recommends a first article, as well as casting in a .25″ thick test slug for durometer measurement. This, again, may add to the timeline though this extra time investment will ensure accurate part delivery.
Need A Material Not Listed? Please Speak With A Fathom Expert Directly About Additional Material Options
Before choosing urethane casting for your project, it is important to note the advantages.
Advantages of urethane casting include //
Many industries use urethane casting for their projects. Urethane casting can be a smart choice for a lower-quantity project as investing in injection mold tooling can be expensive. Another advantage of urethane casting is that it is optimal for use as a first production run, serving as a cost-saving measure to test prototypes before larger-scale production. Advanced prototyping is also feasible with urethane casting because the tooling and design changes cost less than with other manufacturing methods. It is also possible to test a variety of materials from a single mold. Parts made using urethane casting can also be used for customer testing. Still, a high quality, high performance and precise part can be produced.
Some of these applications include //
Both urethane casting and 3D printing are popular manufacturing methods for producing a lower volume of parts. 3D printing is an additive manufacturing process that begins with a CAD design and then uses a machine to build the piece in layers. In urethane casting, the master mold is first produced, usually by a 3D printing method, then the mold is used to create a cavity of the product in silicone. Urethane or other liquid resin is poured into the cavity to form the part. When it comes to selecting a material, there are limitations with both methods. 3D printing does allow for a broader range of plastic and metal material. The material used for urethane casting is limited to rubber or plastic that will cure at room temperature. 3D printing is an excellent choice for prototyping and intricate, iterative designs as well as for creating replicas. Each method has different capabilities and costs, each having its own unique advantage depending on a project’s needs.
There are a number of differences between urethane casting and injection molding that may determine which method is best for your project. Injection molding is more expensive than urethane casting. Injection molding tooling can cost thousands to tens of thousands of dollars, whereas urethane casting costs range from hundreds to thousands. Injection molding uses a real plastic material, but urethane molding uses polyurethanes, which simulate the plastic used in injection molding. Both processes can be used for over-molding onto plastic or metal parts. One of the most substantial differences is volume; injection molding can be used to create a prototype, bridge and high-volume production in the thousands. Urethane casting is best for prototype, bridge and production parts in the hundreds.
A // Larger parts can be reviewed by the project to determine size capabilities.
A // On average, up to 25 parts. If the design includes many sharp edges, this may cause the mold to deteriorate more quickly.
A // First, a design is created using CAD software or a model is provided by the client. A 3D printed master model is created and then encased in silicone rubber. Once the silicone has cured, the master model is removed. The cavity left behind is the mold tool.
A //Absolutely. While urethane casting is popular for rapid prototyping, this method can be used as a bridge tooling process to get the product to market for testing during simultaneous production tooling. It is also perfect for final products when the quantity needed is low to medium.
A // No, Fathom will work with you to ensure your parts are of high quality.
A // Urethane casting is sometimes referred to as urethane molding.
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From models to prototypes for short-run applications like product trials, urethane casting is a great way to fabricate a low-volume of parts that accurately mimic the color, texture, feel and other physical properties achieved as if it was an injection molded part.
At Fathom we offer a unique advantage of speed and agility-our experts help companies go from concept to prototype to manufacturing in ways not previously possible.
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