Acetal (Delrin / POM)

POM-H (Delrin) is slightly stiffer and has higher tensile strength, but is prone to centreline porosity in thick rod sections, which can cause issues on critical sealing surfaces. POM-C is more uniform through the cross-section, slightly easier to machine and the right pick for most fabrication work. For ultra-high-stiffness thin parts, POM-H still wins.

No. Acetal absorbs only around 0.2 percent water at saturation, compared to 2.5 to 3.0 percent for nylon. This is why acetal is preferred for parts that need to hold tight tolerances in humid, wet or temperature-cycled service. For precision instrumentation, fluid handling and measurement parts, acetal is the safer choice.

Yes. Food-grade acetal certified to FDA 21 CFR 177.2470 is available and widely used for food processing valves, fittings, chain guides and conveyor parts. Specify food-grade at quote time so we draw from the right stock.

Acetal cannot be welded the way polyolefins can, and it does not respond well to most solvents or adhesives because of its low surface energy. For permanent joints we use epoxy bonding (with surface preparation), or design the part for mechanical assembly (screws, snap fits, press fits). Plasma or flame treatment helps with epoxy bonding.

Acetal resists oils, fuels, alcohols and most neutral solutions, but is attacked by strong acids and strong oxidisers (concentrated nitric acid, hydrogen peroxide above 10 percent, chlorine). For acid-handling parts step up to PVDF or PTFE. Always check chemical compatibility against the SDS before quote.

Acetal holds its strength well to around 100°C continuous and tolerates short-term peaks to 140°C. Above 100°C the material begins to soften and creep, so for sustained hot service we recommend PEEK or PPS.

Yes. Send us a DXF, DWG, STEP or PDF and we will quote machined acetal parts to your tolerances. Acetal is one of the easiest engineering plastics to hold tight tolerances on, with most parts shipping within 5 to 10 working days from order.