Delrin / Acetal Manufacturers & Suppliers

Delrin homopolymer (polyoxymethylene-H) is produced by DuPont from formaldehyde polymerization with acetal end groups that provide moderate thermal stability. Its tensile strength of 10,000 psi and hardness of Rockwell M94 make it the stiffer, slightly stronger option preferred for precision gears, snap-fit mechanisms, and sliding wear surfaces. Acetal copolymer (POM-C) incorporates comonomer units that interrupt the regular chain structure, reducing crystallinity slightly but eliminating the surface porosity in thick stock that homopolymer exhibits due to its tighter crystallization behavior. For parts machined from rod stock over 3" diameter, copolymer's better thick-section properties often justify choosing it over Delrin. Copolymer also outperforms Delrin in hot water above 180°F and in caustic environments, where Delrin's end groups can unzip and cause dimensional instability.

Acetal homopolymer and copolymer both meet FDA 21 CFR 177.2470 and NSF 51 requirements for food-contact applications, making them broadly accepted for beverage dispensing components, conveyor guides, meat processing equipment, and dairy fittings. The material's inherently low moisture absorption (0.2% at saturation versus 1-7% for nylon) means dimensional stability in washdown environments is substantially better than nylons — gears and cams maintain their dimensional fit through wet-dry cycles. Acetal does not support bacterial growth and cleans easily with standard food-industry sanitizers. Its FDA status covers natural (white) and colors produced from approved pigments. Hot water above 180°F and certain sanitizer chemistries (particularly iodine-based or strong oxidizers) can cause surface degradation over time — verify chemical compatibility with the specific sanitizer used in the application.

Acetal is frequently cited as the easiest engineering plastic to CNC machine due to its predictable, clean chip formation, low tool wear, and ability to hold tight tolerances without the heat management challenges of PEEK or the gummy behavior of polyethylene. At surface speeds of 500-1000 SFM with sharp carbide tooling, Delrin produces well-broken chips and excellent surface finish. Key precautions: the material has a relatively low softening point (338°F / 170°C), so tool rubbing or dwell generates heat that causes localized melting and built-up material on tool edges — consistent chip loads and air-blast chip clearing prevent this. Acetal also responds well to injection molding, but molded parts contain residual stress and gate vestige that can cause dimensional drift when machined — machining from annealed extruded rod stock is preferred for tolerances tighter than ±0.003".