Delrin® (Acetal)
One of the most machinable engineering plastics we stock, and the one engineers reach for when a part has to hold its size. In sheet, rod and tube.
Delrin typical properties
Figures are for unfilled acetal homopolymer stock shapes (Ensinger TECAFORM AD, made from Delrin 150 series resin, and MCAM Acetron). These are typical values, not a specification. The datasheet behind each figure is linked in its row: the manufacturer’s where one publishes the figure, a distributor’s otherwise. Figures vary by supplier and test method, so confirm against the datasheet for the grade and stock form you are designing with.
| Property | Typical value |
|---|---|
| Density | 1.41g/cc |
| Tensile strength | 11,000psi |
| Tensile modulus | 350,000psi |
| Flexural modulus | 470,000psi |
| Hardness | 94Rockwell M |
| Izod impact, notched | 1.0ft-lb/in |
| Max continuous service temp | 180°F manufacturer rating (continuous, 20,000 h in air)MCAM Acetron / Ertacetal H POM-H product datasheet (rev 2023-03-07) (opens in a new tab) |
| Heat deflection temp @ 264 psi | 250°F |
| Water absorption, 24 h | 0.2% |
| Thermal expansion (CTE) | 6.8×10⁻⁵ in/in/°F |
| FDA food contact | Yes, natural grade Applies to natural Delrin 150SA and Acetron POM-H stock under 21 CFR 177.2480. Black and filled grades are not covered. The linked brochure lists the grade as FDA compliant; the CFR section is from the k-mac Plastics and Ready Plastics grade pages. Confirm the grade on the mill cert. |
What Delrin is
High-strength acetal homopolymer with excellent dimensional stability and machinability.
Why engineers specify it
Dimensional stability is the reason Delrin gets picked. It machines cleanly to a good finish and a machined part keeps its dimensions in service, which is what makes it the default for gear and bushing work.
Machining Delrin
Delrin is among the easier engineering plastics to machine, but it moves with temperature — worth planning for thermal expansion on long parts and relieving stress before a finishing pass.
Machining Delrin and acetal: tolerances and tipsNeed Delrin parts machined to print?
Send us a drawing and we will quote it. Precision plastic machining in Linden, New Jersey since 1968.