⚪ DELRIN / ACETAL
Delrin and Acetal Machining in Greensboro, NC
If a Greensboro part has to slide, mesh, or hold a tight dimension and metal is overkill, odds are it gets made from acetal. Sold most famously as Delrin, acetal is the go-to machinable plastic for gears, bushings, rollers, manifolds, and precision mechanical parts across the Triad's transportation and equipment work. This page sorts out Delrin versus copolymer versus homopolymer, explains why acetal machines so beautifully, and shows how local buyers source the right grade.
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Acetal, chemically a polyoxymethylene or POM, is one of the most machined plastics in the Triad for a simple reason: it does the everyday mechanical jobs better than almost anything else in its price class. It is rigid and strong for a plastic, has excellent dimensional stability, low moisture absorption, a naturally low coefficient of friction, and good wear resistance and fatigue life. That combination is exactly what gears, bushings, bearings, rollers, cams, wear strips, and precision mechanical components need.
For Greensboro's transportation, heavy-equipment, and automation work, acetal is everywhere in the supporting hardware: sliding and rotating components, fluid-handling fittings and manifolds, electrical insulators, and the countless small precision parts that keep machinery moving. It is the default whenever an engineer wants a metal-replacement part that moves against another surface, holds tolerance, and does not need acetal's pricier cousins like PEEK.
Delrin is DuPont's brand name for acetal homopolymer, and the name has become shorthand for the material in general, much as machinists say the brand when they mean the polymer. Knowing that Delrin specifically refers to a homopolymer, while plenty of acetal stock on the market is copolymer, is the first step to specifying it correctly, because the two have real differences that matter for some applications.
Delrin 150, Homopolymer, and Copolymer
Delrin 150 is a specific, widely used grade of acetal homopolymer, an unfilled general-purpose stock prized for high stiffness, strength, and excellent machinability. It is a common default for gears, bushings, and precision machined parts where you want the homopolymer's higher rigidity and surface hardness. When a print calls out Delrin 150, it is specifying that homopolymer grade rather than a generic acetal.
Acetal homopolymer, the Delrin family, offers slightly higher tensile strength, stiffness, and surface hardness than copolymer, which is why it is favored where maximum rigidity and wear performance matter. Its one known quirk is a tendency toward centerline porosity in thicker extruded or molded sections, a small internal void at the core that can matter for sealing or pressure parts but is irrelevant for most mechanical components.
Acetal copolymer trades a touch of that peak stiffness for better long-term thermal stability, superior resistance to hot water and a broader range of chemicals, and freedom from the centerline porosity issue, giving more uniform stock through the cross-section. It is often the better choice for parts exposed to hot water, certain chemicals, or continuous elevated temperature, and for components where through-section uniformity matters. For Triad buyers the practical guidance is straightforward: homopolymer and Delrin 150 for maximum stiffness and wear in mechanical parts, copolymer for chemical and hot-water exposure or where centerline porosity would be a problem. For most ordinary gears and bushings either works, and availability often decides.
Why Acetal Is a Machinist's Favorite
Acetal is one of the most cooperative materials a Greensboro shop will ever put on a lathe or mill. It machines fast and clean, produces well-broken chips, takes a fine surface finish, and holds tight tolerances thanks to its dimensional stability and low moisture absorption. Unlike many plastics it does not gum, melt easily, or fight the tool, so shops turn, mill, drill, and thread it at high rates with excellent results, which is a big part of why it is the default for precision plastic parts.
The stability point is worth emphasizing for tolerance-critical work. Acetal absorbs very little moisture, so parts do not swell and drift dimensionally the way nylon can in humid service, and that makes acetal the better choice for close-tolerance gears, bushings, and mechanical parts that have to stay on size in real-world conditions. For Triad mechanical and automation work, that predictability is exactly what engineers want.
The one process detail experienced shops respect is residual stress and thermal expansion. Acetal has a relatively high coefficient of thermal expansion for a structural plastic, and thicker parts machined to tight tolerance can benefit from stress relief so they hold dimension after machining. A shop that runs acetal routinely accounts for this and for the material's expansion when holding precision dimensions across temperature, which is the kind of detail that separates a real precision-plastics supplier from a general shop.
Sourcing Acetal Stock and Machined Parts Locally
Acetal is widely stocked and readily available through the Triad supply network in rod, plate, and tube across natural and black, in both homopolymer and copolymer, so material is rarely the bottleneck. The real sourcing decision is finding a Greensboro shop that machines it to the tolerance and finish your application needs and understands the homopolymer-versus-copolymer trade-off well enough to flag substitutions.
For most mechanical work, any capable plastics-machining shop in the area handles acetal comfortably given how cooperative the material is. The cases that warrant a more careful supplier choice are tight-tolerance gears and precision parts where stress relief and thermal-expansion management matter, applications exposed to hot water or chemicals where copolymer should be specified, and regulated work such as medical or food-contact parts that may require specific certified grades and traceability.
The practical approach is to confirm the shop routinely machines acetal to your tolerance class, will use the correct homopolymer or copolymer grade for the service environment rather than substituting blindly, and can provide certification and traceability if the application requires it. ManufacturingBase lets Triad buyers search local suppliers by both the material and the relevant capabilities and certifications, so whether you need a quick run of bushings or a certified batch of precision gears, the right shop surfaces quickly.
Frequently Asked Questions
Delrin is a brand name, specifically DuPont's name for acetal homopolymer, and over time machinists have come to use Delrin loosely to mean acetal in general, much as people use a brand name for a whole product category. But for precise specification it does matter. Delrin refers to a homopolymer, while a large share of the acetal stock on the market is copolymer, and the two have real differences. Homopolymer, the Delrin family, has slightly higher stiffness, strength, and surface hardness, which is why it is favored for gears, bushings, and precision wear parts, but it can have centerline porosity in thicker sections. Copolymer trades a little of that peak stiffness for better resistance to hot water and a broader range of chemicals, better long-term thermal stability, and more uniform stock without the porosity issue. For most ordinary mechanical parts either works fine and availability often decides. But if your part sees hot water, chemical exposure, or you need through-section uniformity, you should specifically call out copolymer rather than just saying Delrin. A good Triad supplier will ask about the service environment and flag the right choice rather than substituting blindly.
Delrin 150 is a specific, widely used grade of acetal homopolymer, an unfilled general-purpose stock known for high stiffness, strength, and excellent machinability. When a drawing calls out Delrin 150, it is specifying that particular homopolymer grade rather than a generic acetal, which gives the shop a defined material to source and machine. You should specify Delrin 150 when you want the homopolymer's higher rigidity, surface hardness, and wear performance for mechanical parts like gears, bushings, rollers, cams, and precision machined components, and when the service environment does not demand the copolymer's superior hot-water and chemical resistance. It is essentially the default homopolymer choice for general-purpose precision plastic parts. If your application involves hot water, aggressive chemicals, continuous elevated temperature, or thick sections where centerline porosity would be a problem, you would specify an acetal copolymer instead. For most dry mechanical applications in the Triad's transportation and equipment work, Delrin 150 or an equivalent homopolymer is a solid, readily machined choice, and any capable Greensboro plastics shop will handle it comfortably.
The main reason is dimensional stability. Acetal absorbs very little moisture, so its parts stay on size in humid and wet conditions, whereas nylon absorbs significant moisture and can swell and drift dimensionally as it takes on water. For close-tolerance gears, bushings, and precision mechanical parts that have to hold dimension in real-world service, that stability makes acetal the more reliable choice. Acetal also has excellent dimensional stability overall, a naturally low coefficient of friction, good wear resistance, and high rigidity, and it machines cleaner and holds tighter tolerances than nylon, all of which favor it for precision work. Nylon still has its place, particularly where its toughness, impact resistance, or abrasion resistance is the priority, and nylon can outperform acetal in certain wear pairings. But when the governing requirement is holding a tight tolerance predictably, especially in conditions where moisture is present, acetal usually wins. For Triad transportation, equipment, and automation work where precise sliding and meshing parts must stay on size, acetal is the default, and a knowledgeable Greensboro supplier will recommend it over nylon for exactly that dimensional-stability reason.
For many ordinary parts, no, but for tight-tolerance precision work, especially thicker sections, stress relief is worth considering. Acetal machines beautifully and is dimensionally stable in terms of moisture, but it has a relatively high coefficient of thermal expansion for a structural plastic, and stock can carry some residual internal stress that releases during machining and slightly distorts the part. For close-tolerance gears, precision bushings, and parts where a few thousandths matter, an experienced shop may stress-relieve the material, sometimes annealing between roughing and finishing, so internal stresses settle before final cuts and the part holds its dimension afterward. The shop will also account for acetal's thermal expansion when the part must hold precision across a range of temperatures, since the material moves more with temperature than metal does. This is the kind of detail that distinguishes a real precision-plastics supplier from a general shop that occasionally cuts plastic. For routine mechanical parts where tolerances are not critical, acetal can simply be machined and used as-is given how stable and cooperative it is. A capable Greensboro shop will know when stress relief is warranted for your specific tolerance class.
Acetal is one of the most widely stocked machinable plastics, so it is rarely a sourcing bottleneck in the Triad. It is available through the regional supply network in rod, plate, and tube, in both natural and black, and in both homopolymer and copolymer forms, so the common sizes and grades are generally on hand or quick to get. That ready availability is part of why acetal is the default for so much precision mechanical work: a Greensboro shop can usually start machining without a long material lead time. The cases where you should plan ahead are less common grades or forms, large sizes, or applications that require a specific certified grade, such as medical or food-contact parts needing traceability, which may need to be ordered to spec. For most transportation, equipment, and automation work, though, standard acetal stock is readily accessible and any capable plastics-machining shop in the area keeps or quickly sources it. On ManufacturingBase you can search local suppliers by both the material and the certifications you need, so whether it is a fast run of bushings from stock or a certified batch of precision gears, you can line up the right shop quickly.
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Last updated: July 2026
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