Custom Molded O-Rings
Compression Molded & Continuously Molded O-Rings

When standard AS568 sizes, common metric dimensions, or very large diameters cannot meet application requirements, custom-molded O-rings provide an effective solution. Non-standard sizes can be manufactured using either compression molding or continuous molding processes. Compression-molded O-rings are suitable for both static and dynamic sealing applications and are typically the preferred choice for high-volume production of smaller, non-standard dimensions.
For larger or unconventional sizes, continuously molded O-rings offer greater flexibility. This process eliminates the need for dedicated tooling and can accommodate virtually any inside diameter, making it ideal for large-scale dynamic applications or lower production volumes where tooling costs are not justified.
In addition, continuously molded O-rings perform well in both static and dynamic environments, including high-pressure and vacuum conditions. They can be produced in a wide variety of material types, hardness levels, inside diameters, and cross-sectional profiles to meet specific performance requirements.
Comparisons Between Custom O-Ring Techniques
Continuous molding delivers performance comparable to compression molding, with both processes suitable for static and dynamic sealing applications. For large-diameter O-rings produced in moderate quantities, continuous molding is often the preferred option since it eliminates the need for tooling.
In contrast, compression molding requires dedicated tooling but becomes more cost-effective for high-volume production. Vulcanized O-rings, which can be manufactured within a short timeframe and without tooling, are typically used for static sealing applications.
| 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 |
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 +8618730921709 or submit the Product Inquiry Form.