O-Rings From 1 mm ID to 7000 mm across

An O-ring is one of the cheapest parts in a machine. But when it fails, it usually grinds productivity to a halt. What it costs you is the downtime and the labour of getting the old one out and a new one in, not just the part cost.

Sizes, grades and tooling

We already hold over 3,000 O-ring moulds, so there is a good chance your size needs no new tooling. The largest O-ring we have made is 7000 mm in diameter. For large diameters, confirm the manufacturing method with us: moulded or joined construction must suit the application. Specify inside diameter, cross-section, joint requirements and tolerances before ordering.

Choose the compound for the application

Compound selection, compression set, dimensions and operating conditions all affect sealing performance. Consider these alongside the purchase price.

Service life depends on the compound, installation and operating conditions. Compare suitable grades and replacement costs for your application; a fixed increase in service life cannot be assumed.

White filler and skipped post-curing

The failure we see most is an O-ring that has had white mineral filler added to make it cheaper. Its compression set is poor, it takes a set in the groove, and it stops sealing.

The second is post-curing. Many compounds need it to reach their compression set properties, and very few makers do it the way they should. We post-cure where the compound and the application need it. That covers most silicone parts, and the O-rings that call for it.

Our Purity Promise explains how we deal with filler, and you can ask us for the ash content of your O-rings.

You know who made it

Buy from us and you know who mixed the compound and who moulded the part, because both happen here. Every batch of compound is checked for hardness, cure and porosity before it is used, and every cavity of a mould is checked before production starts. More on that is on the moulded gaskets page.

O-rings