There are many reasons why a custom o-ring is used as apposed to an off-the-shelf o-ring. An o-ring may need to fit a specific design, instead of having to design a product around a standard size o-ring. A special material may be required, low coefficient of friction, a softer or harder rubber, or the shape oval instead of round. Sometimes a part may be out of spec and using a custom o-ring would allow bringing the project to production much faster.
Custom o-rings are used in many types of products where standard o-ring seals are used, especially if a sealing problem or other issue has surfaced. Many times a product can’t be design around a standard seal and using a custom seal is the only solution. Valve manufacturers use custom o-rings, sometimes they require a non-standard size or a special compound with low friction properties to assist the valve in operating smoothly.
The Custom O-Ring Process
When considering a custom o-ring the first criteria Satori Seal looks at is the reason a custom o-ring is needed. Is it size, material, shape? Is the customer trying to resolve a problem? And if so, what is the current problem? If the reason is size, we look at the application and retrieve specific measurements. We can then design a seal with the proper dimensions that will provide a tight, long lasting seal. Sometimes a special rubber material is needed such as an internal lubed compound for low coefficient of friction or a material with increased low temperature or abrasion resistance. There are many reasons why a special material may be required and Satori Seal can assist in selecting a material that will work in the application. Once the dimensions and material are selected, Satori Seal can get samples manufactured from a prototype tool. This is a 1-2 cavity, low cost tool used to produce a few samples for testing purposes. Prototype tools are great because several cavities can be cut to test different size o-rings in the product before a more costly production tool is produced.
Common Materials Used With Custom O-Rings
The 5 most common rubber materials used with custom o-rings are Nitrile, EPDM, Viton® (fluorocarbon), Silicone and Neoprene® (chloroprene). Nitrile is a great all purpose compound that is highly resistant to oils, greases, solvents and hydraulic fluids. It has good physical properties and temperature range from -40°C[-40°F] to +100°C[+212°F]. EPDM rubber is extremely resistant to ozone, weathering, water and steam. It has a broad temperature range from -55°C[-67°F] to +125°C[+257°F]. Viton® (fluorocarbon) offers increased oil, solvent and chemical and heat resistance, over 232°C [450°F], than other common elastomers. Silicone offer a high degree of resistance to ozone, heat, UV light, general weathering, ozone and compression set. It has the broadest temperature range from -65°C[-85°F] to +232°C[+450°F] with special compounds that are heat resistant to 315°C[+600°F]. Neoprene® (chloroprene) exhibits good abrasion, chemical, flex, heat, oil, weather and ozone resistance. It’s good in dynamic applications because of its toughness.
Experts in Rubber Seals
We supply custom o-rings to many industries especially the automotive, medical devices, industrial and consumer product industries. We assisted in designing a custom o-rings for an automotive valve when the need for low break-out (limiting) friction was required. We used an o-ring with a custom thickness that was not available off-the-shelf and made with a rubber material specially formulated with low friction properties. This allowed the valve to function within the specifications it was originally designed to operate. We’ve assisted in designing custom o-rings for our customer’s parts that were produced out of specification. Instead of having to scrap or rework high cost parts, we suggested the use of a custom o-rings that was significantly cheaper than scrapping or reworking high cost parts.