Seals may of themselves appear to cost a lot, but this is only a fraction of the cost of the equipment that they protect. The difference between an average quality seal with a good one is only a matter of a few dollars.

A look at how seals are manufactured at Oz Seals, Australian manufacturer of quality sealing systems, helps to explain the difference between good and bad seals.

An average quality seal starts with average quality raw materials. Even polyurethane (PU) which is considered a premium raw material is not always so. At Oz Seals, only high quality virgin PU raw material is used. All Oz Seals PU materials are polyether-based.

Polyether-based materials have higher hydrolysis resistance and better flexibility at lower temperatures than polyester-based polymers.

Designated as super polymers, Oz Seals seal stock is also unique in that they are thermoset and spin cast, using the company?s proprietary Poly4 four-component processing plant. This unique production plant is a fully enclosed process, working in a controlled atmosphere environment, with inert gases to prevent contamination.

The plant is also highly accurate and able to safely handle difficult pre-polymers and curatives than other processing plants. Application of heat is part of the process, with bubble-free polymer the result. The resulting moulds go through a further spinning process. In comparison, conventional thermoplastic polyurethanes are injection moulded and can use up to 60% recycled materials.

Oz Seals only uses 100% virgin raw material to produce a stable and void-free base stock. Thermoplastic material is also less stable than thermoset material.

Another difficulty with injection-moulded seals is that they soften rapidly as temperature a increase?which leads to extrusion and nibbling failure patterns in the stock. Injection moulding also tends to create voids inside the seal, as this is moulded. The presences of voids (or bubbles) can and usually cause the sudden failure of seals.

Injection moulding is also not economical on short runs. The lower tooling cost of thermoset spin casting allows Oz Seals to produce short runs and one-seal production of specialty seals.