Cast Rubber Grommet

A small rubber grommet, cast in polyurethane rubber by moulding and casting. The part has a smooth sealing face on top, a ribbed and toothed underside and a central bore, all of which have to come out crisp for it to do its job. Rather than commission expensive injection tooling for a part like this, we made a mould and cast it, which is faster and far cheaper for the quantities involved.

Cast, not injection moulded

Casting rubber in a mould is the practical way to make small runs of a part like this. We built a mould around the grommet’s shape and poured polyurethane rubber into it, a material chosen for being tough, flexible and hard-wearing. The pour picks up every detail: the ribs around the side, the fine teeth on the underside and the clean central hole. It is the same result an injection-moulded part would give, without the tooling cost or lead time.

A durable finished part

Polyurethane rubber makes a grommet that flexes and grips without tearing, so it stands up to real use. Once demoulded, each part is trimmed and checked so the edges are clean and the bore is true. It is a straightforward piece of our moulding and casting work, turning a single design into a functional rubber part ready to fit.