⚪ DELRIN / ACETAL

Delrin and Acetal Machining in Lima, OH — Delrin 150, Homopolymer, and Copolymer Grades

Acetal — sold as Delrin by DuPont in homopolymer form and as Celcon or Ultraform in copolymer variants — earns its place in Lima's manufacturing supply chain through a combination of properties no other low-cost engineering plastic matches: a fatigue endurance limit that supports gear and cam applications, a coefficient of friction low enough for unlubricated sliding, dimensional stability within 0.001 inch per inch across a wide humidity range, and machinability that rivals aluminum on the CNC mill. Buyers sourcing from Lima's industrial base find acetal in applications spanning automotive gear train components to defense electronics enclosures.

ISO 9001AS9100
Delrin 150 is DuPont's standard acetal homopolymer grade — medium viscosity, optimized for injection molding but equally well-suited to machining from rod and plate stock. Tensile strength of approximately 10,000 psi, flexural modulus of 410,000 psi, and Rockwell M hardness of 94 characterize its mechanical profile. What distinguishes Delrin 150 from acetal copolymer is its crystallinity: the homopolymer structure gives higher yield strength, better fatigue resistance, and a harder surface. For Lima's gear and cam applications — including instrument drive gears in automotive assemblies and detent mechanisms in defense electronics — Delrin 150's fatigue endurance limit of approximately 4,500 psi at 10 million cycles makes it suitable for continuous cycling loads that would creep or fracture nylon. Lima CNC shops machine Delrin 150 at 600-1,000 SFM with sharp, high-positive-rake carbide or HSS tooling. The key technique is avoiding heat buildup — acetal melts at approximately 347 degrees F and begins smearing rather than cutting cleanly if surface speed and chip load are mismatched. Air blast or mist coolant is preferred over flood coolant because Delrin is dimensionally stable to moisture and flood coolant cleanup on plastic parts is time-consuming without benefit. Tolerances of ±0.001 inch on bored diameters and ±0.002 inch on turned ODs are standard in production, holding to room temperature measurement at 68 degrees F.

Acetal Homopolymer vs. Copolymer: Choosing the Right Variant for Allen County Applications

The structural difference between acetal homopolymer (Delrin) and copolymer (Celcon, Ultraform) comes down to two practical distinctions: centerline porosity and chemical resistance. Homopolymer acetal rods above approximately 3 inches in diameter develop a porous core during solidification of the billet — a natural consequence of the highly crystalline structure's volumetric shrinkage. For through-bored parts like large bushings or gear hubs machined from the center of rod stock, this centerline void can cause dimensional instability or visual defects. Acetal copolymer maintains a more uniform structure through large cross-sections, making it the better choice for parts requiring material at the centerline of large-diameter rod. Acetal copolymer also resists alkalis and certain organic solvents better than homopolymer, which matters in Lima's oil equipment and chemical-adjacent manufacturing. Pump impellers, chemical-resistant gear trains, and fluid-handling components that contact caustic cleaning solutions or glycol-based fluids are typically specified in copolymer grade. Tensile strength of acetal copolymer (approximately 8,500 psi) is slightly lower than Delrin 150, and its fatigue resistance is marginally lower, but for most Lima industrial applications the difference is not design-limiting. For food-contact or FDA-compliant applications — which arise occasionally in Lima's industrial equipment sector for food-grade pump components and conveyor parts — both Delrin 150 and acetal copolymer are available in FDA 21 CFR 177.2470-compliant grades. Buyers should specify the FDA-grade requirement explicitly, as standard production grades may include colorants or lubricant additives not cleared for food contact.

Gear, Bushing, and Wear Component Design Guidelines for Lima Buyers

Acetal's low friction coefficient (0.20-0.35 against steel, dry) and PV limit of approximately 3,000 psi-ft/min make it a standard material for unlubricated bushings, wear pads, and slide plates in Lima's automotive and industrial assembly applications. Bearing bushing design in acetal should provide 0.001-0.002 inch diametral clearance per inch of shaft diameter to allow for slight thermal expansion and prevent seizing; too little clearance causes friction heating that softens the acetal and rapidly accelerates wear. Gear design in Delrin follows AGMA standards with module selection matched to load, but tooth profile should be cut to AGMA Quality 8 or better to minimize noise in precision mechanisms. Lima shops with hobbing capability or CNC gear milling produce acetal spur gears to Q8 routinely. Tooth root fillet radius of at least 0.25 times module is critical — sharp root fillets in acetal concentrate stress at the high-cycle fatigue initiation site. For mating metal-to-Delrin gear pairs, the metal gear should be the driver if possible, allowing the acetal gear to conform to the metal profile as wear occurs rather than gouging the harder metal surface. Wear plates and slide pads in Delrin for conveyor and assembly fixture applications in Lima's automotive tier shops are typically bonded with structural adhesive (3M DP-810 or equivalent) to steel backing plates. Countersunk screw attachment is also used when adhesive is not appropriate; self-tapping screws in Delrin should be torqued carefully because the material's ductility makes over-torquing and thread stripping easy. Acetal does not accept primer or paint adhesively — mechanical attachment is the only reliable fastening method for load-bearing assemblies.

Frequently Asked Questions

Choose Delrin 150 homopolymer when the application demands maximum fatigue resistance, highest surface hardness, and best mechanical properties — gear teeth, cam followers, and precision wear surfaces in small-to-medium cross-sections (under 3 inch diameter) where centerline porosity is not a concern. Choose acetal copolymer when the part is machined from large-diameter rod (3 inch or greater) to avoid the centerline void inherent in homopolymer billets, when the application contacts alkalis or solvents that attack homopolymer preferentially, or when FDA compliance is required and a copolymer-based FDA grade is specified. Both grades machine similarly, hold equivalent dimensional tolerances, and are available from Midwest plastics distributors at comparable prices. The choice is application-driven, not cost-driven — and Lima shops familiar with both materials can advise based on your drawing and operating environment.
Standard CNC turning and milling of Delrin in Lima produces ±0.001 inch on bored diameters, ±0.002 inch on turned ODs, and ±0.003 inch on milled profiles — all measured at 68 degrees F per ISO standard conditions. Tighter tolerances are achievable with careful fixturing and temperature-controlled inspection but require discussion at quoting because Delrin's thermal expansion coefficient (5.4 x 10-5 per degree F) is roughly twice that of aluminum, meaning a part dimensioned at 68 degrees F in the shop will be 0.003 inch larger on a 2-inch bore when sitting in a 150-degree F machine environment. Buyers with close-clearance fits between Delrin and metal components should identify the operating temperature so Lima shops can apply appropriate compensation. Thread tolerances in Delrin follow 2B class for unified threads; engagement length of 1.5-2x nominal diameter is recommended due to acetal's lower shear strength versus steel.
Yes. Lima shops with hobbing machines or CNC machining centers capable of helical interpolation produce acetal spur and helical gears to AGMA Quality 8 routinely, and some shops achieve Quality 10 with controlled tooling and in-process gear checking. Quality 8 is appropriate for most power transmission gears in acetal at moderate speeds (below 2,000 RPM pitch line velocity). Tooth form accuracy matters more in acetal than metal because acetal's lower elastic modulus means mating gear pairs self-correct less under load — a poor tooth form contact ratio in metal often improves as the gears wear in, while acetal gears wear to the contact pattern dictated by the cut profile. Buyers should specify diametral pitch or module, pressure angle (20-degree standard), tooth count, face width, and required quality class on the drawing. CMM-based gear inspection with profile, lead, and pitch reports is available from Lima shops serving automotive and precision instrument programs.
Acetal performs well in petroleum-based fluids (crude oil, diesel, lubricating oil, gasoline) and resists most non-oxidizing acids and neutral salt solutions — chemical service common in Lima's oil refining equipment and pump manufacturing sector. Its limitation is oxidizing acids (nitric acid, chromic acid), strong alkalis (sodium hydroxide above 5% concentration), and some polar solvents (methanol, acetone at elevated temperature), which degrade acetal surface integrity over time. For Lima oil equipment applications, the relevant exposures are typically hydrocarbons and brines — both well within acetal copolymer's capability. Acetal seals and valve components should be avoided in steam service above 212 degrees F because the continuous service temperature limit is approximately 220 degrees F, and steam at saturation pressure contacts at 212 degrees F with thermal cycling that approaches the limit. PEEK or PTFE are better choices for steam-service components in Lima's refinery equipment applications.
Midwest plastics distributors serving Lima stock Delrin 150 homopolymer and acetal copolymer in round rod from 0.25 inch to 6 inch diameter, plates from 0.125 inch to 4 inch thick in standard 24 x 48 inch and 24 x 24 inch blanks, and tubular sections in common bore sizes. Natural (white/ivory) and black (with UV stabilizer) colorways are standard for both grades; FDA-grade natural Delrin 150 and copolymer are stocked in rod and plate. Delivery to Lima from Columbus or Cleveland distributors is typically 1-3 business days on standard items. Special sizes — large-diameter rod above 6 inch, specialty colors, or Delrin AF (PTFE-filled, for enhanced low-friction applications) — require 1-2 week lead time from manufacturer stock. ManufacturingBase-listed Lima shops can advise on material availability and pricing at quoting, allowing buyers to compare single-source machining-plus-material quotes against split-source options.

Related Pages

Delrin / Acetal in ClevelandDelrin / Acetal in CincinnatiDelrin / Acetal in DaytonDelrin / Acetal in ToledoDelrin / Acetal in AkronDelrin / Acetal in YoungstownDelrin / Acetal CNC MachiningDelrin / Acetal Swiss MachiningDelrin / Acetal EDM / Wire EDMDelrin / Acetal Laser CuttingDelrin / Acetal Stamping

Last updated: July 2026

Find Delrin / Acetal Manufacturers in Lima, OH

Search verified Lima shops that work in Delrin / Acetal.

Search Manufacturers →Get Your Shop Listed (Free)

No logins. No email gates. Just results.