Urethane Casting

When multiple parts are needed, urethane casting can help bridge the gap between prototyping and production. Advanced Prototype Molding provides urethane casting services for prototypes, pre-production parts, and select production applications. Cast urethane parts can be produced in a wide range of sizes, shapes, materials, colors, and finishes. Color can be matched using a Pantone number or a physical color chip.

Advanced can also meet specific part requirements with options for inserts, over-molding, copper shielding, molded-in color and texture, and painted custom colors and textures.

Typical uses for cast urethane parts include fit and function testing, product development, and marketing materials. In some production applications, urethanes can also be used for finished parts, particularly when thick walls or specific chemical resistance are required.

Urethane casting is a manufacturing method similar to injection molding in that polyurethane material is introduced into a mold to form the finished part. The difference is that urethane casting typically uses a softer silicone mold rather than the hard tooling associated with injection molding. This makes the process well suited to the small, multi-piece runs that often occur between prototyping and full production.

Advanced Prototype Molding offers urethane casting services for prototyping, pre-production, and production applications. Related capabilities include:

• Urethane casting
• RTV molding
• Material recommendations
• Additional finishes

A Primer on Urethane Casting

Urethane casting is a fast and flexible manufacturing method for creating prototypes and low-volume production parts. Silicone tooling can be customized to reproduce detailed part geometries, while a wide range of polyurethane materials and finishing options allows cast urethane parts to be produced according to specific application requirements.

What Is Urethane Casting?

Urethane casting uses a softer silicone mold compared with the harder machined molds commonly used for injection molding. Polyurethane materials can be selected to produce rigid, flexible, or rubber-like parts depending on the desired properties.

The process is well suited to complex parts, components, and products because detailed silicone molds can reproduce intricate design features. This flexibility makes urethane casting useful at different stages of product development, from early prototypes and fit and function testing to pre-production and certain production applications.

How It Works

Urethane casting starts with the creation of a master pattern, which is a three-dimensional representation of the final product. The master pattern defines the features of the finished part and is used to create the silicone tooling.

Master patterns can be produced using several methods. Designers can create a CAD or CAM file and use CNC machining to produce the pattern, or the master can be 3D printed.

Once the silicone tooling is prepared, the selected polyurethane material is introduced into the mold. Vacuum, heat, and pressure can be used during processing to help the material completely fill the mold and reduce trapped air. After the material cures, the finished cast urethane parts are removed from the mold and can receive additional finishing or customization as needed.

Advantages of Urethane Casting

There are many advantages to using urethane casting over other molding or manufacturing processes. These include:

• Lower initial tooling costs: Silicone tooling can be produced more quickly and economically than many hard molds used for injection molding.
• Cost-effective for smaller runs: Urethane casting can be a practical option when only a limited number of parts are required.
• Fast production: The tooling and casting process can provide shorter turnaround times for prototypes and low-volume production.
• Detailed parts: Silicone molds can reproduce complex geometries, intricate features, and fine details from the master pattern.
• Material variety: Polyurethane materials are available in different levels of hardness, flexibility, and density.
• Custom appearance: Cast urethane parts can be produced with different colors, textures, and finishes to meet product requirements.
• Production flexibility: Urethane casting services can support prototype development, pre-production runs, and certain low- and mid-volume production applications.

Urethane Casting Materials

Material selection is an important part of the urethane casting process. Advanced Prototype Molding can help identify polyurethane materials based on the physical properties and performance requirements of the finished part.

A variety of materials and additives can be used to achieve different characteristics, colors, finishes, and textures.

Four common material categories include:

1. Elastomeric, Shore A: Softer and flexible urethane materials suitable for parts that require flexibility.
2. Rigid, Shore D: Harder materials that can produce rugged and impact-resistant parts.
3. Expanding Foam: Foam materials available in densities ranging from soft and low-density to high-density and rigid.
4. Silicone Rubber: Typically platinum-based materials used for certain small, high-contact parts.

Material and additive combinations can also be selected to meet specific industry requirements. Depending on the material and application, options are available for requirements such as UL 94-VO and FAR 25.853 flammability ratings, as well as cleanliness requirements associated with certain medical and pharmaceutical applications.

Common Applications

Urethane casting services are used across a range of industries because they can produce functional parts with different material properties and appearances without the tooling investment associated with some conventional production methods.

Industries that use urethane casting include:

• Aerospace
• Automation
• Automotive
• Consumer products
• Dental and medical
• Electronics
• Industrial production
• Military and defense
• Robotics

Cast urethane parts can be used for a variety of applications, including:

• Aerospace panels
• Bellows
• Boots
• Bumpers
• Cosmetic tools
• Covers for electronic, medical, and dental products
• Fans
• Household goods
• Industrial pipes, tanks, and fittings
• Lenses
• Over-molded components
• Packaging
• Prototypes
• Products requiring UL flammability ratings
• Toys

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Custom Urethane Casting Options

Urethane casting can be customized to meet functional, appearance, and assembly requirements. Advanced Prototype Molding can provide options such as:

• Inserts: Components can be incorporated into cast urethane parts to support assembly or specific functional requirements.
• Over-molding: Urethane can be molded around another component or material when the design calls for an integrated part.
• Copper shielding: Copper shielding can be incorporated into applicable parts where shielding is required.
• Molded-in color and texture: Color and texture can be incorporated during the casting process.
• Custom colors and textures: Parts can also be painted or finished according to specific requirements.
• Color matching: Cast urethane parts can be color-matched using a Pantone number or physical color chip.

These options allow prototype and production parts to more closely represent the intended appearance and functionality of the final product.

Urethane Casting Services at Advanced Prototype Molding

Advanced Prototype Molding provides urethane casting services for prototypes, pre-production, and production applications. Our team can assist with material selection and provide customized cast urethane parts with inserts, over-molding, copper shielding, colors, textures, and additional finishes.

For projects that require silicone tooling as part of the urethane casting process, Advanced also provides RTV molding services.

Advanced Prototype Molding also offers a variety of other manufacturing services to support projects from initial product development through production.