Compression Molded & Continuously Molded O-Rings

When nonstandard-size o-rings are required but don’t quite fit into standard AS568, common metric sizes, or are extremely large, custom molded o-rings are recommended. A full range of non-standard o-ring sizes can be custom-made with compression molding and continuous molding.

Compression molded o-rings are produced for static and dynamic applications. Compression molding is preferred when high volumes of small and non-standard sizes are needed.

Continuously molded o-rings are an excellent sealing option for large, non-standard size dynamic applications. Our continuous molding process does not require tooling and can handle virtually any ID size. It is also the best option for smaller amounts of dynamic o-rings where the volumes do not warrant having a tool cut.

Continuously molded o-rings can be used for both dynamic and static applications, as well as high-pressure and vacuum environments. Continuously molded o-rings can be produced in numerous combinations of material, durometer, ID, and cross-section.

Comparisons Between Custom O-Ring Techniques

The performance of continuous molding is similar to that of compression molding, with both being made for static and dynamic applications. For modest volumes of large-diameter o-rings, continuous molding is optimal as there is no tooling cost. Compression molding requires tooling but can be ideal when producing a large volume of o-rings. Vulcanized o-rings can be produced within hours and do not require tooling, and are best suited for static conditions.

Continuous Molding Compression Molding Vulcanized
Tensile Strength Excellent Excellent Good
Lead Time 4-6 Weeks 10-12 Weeks Same/Next Day
Tooling Cost No Yes No
Dynamic/Static? Both Both Static

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Custom O-Ring Recommendation by O-Ring Size, Application, and Volume

Application Micro Sizes

ID: >0.5mm (.019 in.)

Nonstandard Sizes

ID: >75mm (3 in.)

Nonstandard Sizes

ID: >800mm (31 in.)

Large Sizes

ID: >2,500mm (96 in.)

Static Compression Molding Low Volume (<750): Vulcanization

High Volume (>750): Compression Molding

Vulcanization Vulcanization
Dynamic Compression Molding Compression Molding Low Volume (<100): Continuous Molding

High Volume (>100): Compression Molding

Continuous Molding


To place an order or request more information on custom molded o-rings which molding you require for your application, give us a call at 832-448-5550 or submit the Product Inquiry Form.