On a conveyor, a pulley turns for thousands of hours. The gasket next to it has to stay in place, slide without wearing and keep its dimensions from the first turn to the last.
For an industrial machine builder, we produced two pulley gaskets in polished black POM. Two small parts where everything comes down to a tenth of a millimetre.
The two parts
- a Ø 28.3 mm shaft pulley gasket, 4.5 mm thick, with a Ø 11.5 mm bore held to ±0.1 mm;
- a Ø 32 mm (±0.1 mm) pulley gasket, 4.2 mm thick, with a Ø 14.2 mm bore and a rounded edge.
The first one carries a 0.25 mm sealing lip with a 90° tip. It is the most delicate detail: it has to come out of the mould complete and clean, without flash, on every part.
Why POM
POM (polyoxymethylene, also known by the trade name Delrin) is the reference plastic for mechanical parts that slide and rotate:
- low friction without lubrication;
- very good wear resistance;
- excellent dimensional stability for tight tolerances;
- good stiffness, even in thin sections.
Precision injection moulding
- general tolerances to ISO 20457, class TG5;
- bores held to ±0.1 mm for a play-free fit on the shaft;
- no flash: every part is delivered clean, with no finishing;
- part number and material engraved in the mould for traceability.
On a thin, flat part like this one, the challenge is filling the mould evenly to avoid warping. Mould design and process settings make the difference.
Custom plastic washers, gaskets and rings
Need a part like this produced or replaced? Send us your drawing or 3D file, or even the existing part: we scan it and make it again.
Have a file? Send it here.