Delrin (Acetal/POM) vs. ABS: Strength, Machining, Cost & Selection Guide

Choosing between Delrin® (POM-H) and ABS depends on what the part actually needs to withstand: mechanical load, impact, heat, friction, moisture, chemicals, or manufacturing constraints.

Delrin (Acetal) is stronger, more dimensionally stable, and better for precision moving parts like gears and bushings.

ABS is more impact resistant, easier to mold, and better for housings and cosmetic components.

Choose Delrin for mechanical wear; choose ABS for impact and cost efficiency.

Quick Decision Summary: Delrin vs. ABS

Do not make the final decision from the polymer name alone, both are available in multiple grades with substantially different properties, shown below.

Understanding the Materials: Brand vs. Chemistry

What Is Delrin?

Delrin® is DuPont’s brand for acetal homopolymer (POM-H), available across standard, toughened, lubricated and reinforced grades. Properties vary meaningfully within that one brand name:

Mixed test methods above (ISO vs. ASTM) are not directly comparable to each other or to ABS’s ASTM D256 figures. This is exactly why “Delrin is X times tougher/weaker than ABS” should be checked against same method data, shown in the Impact Resistance section below.

What Is ABS?

ABS (acrylonitrile-butadiene-styrene) is not one material but a broad family, with grades formulated for different combinations of impact strength, flow, heat resistance, flame retardance and UV stability.

Protolabs’ own comparison of standard versus flame-retardant ABS makes the point concretely: standard ABS lists 7.7 ft-lb/in notched Izod at 73°F, while its flame-retardant grade lists 4.0 ft-lb/in at the same temperature, a real property trade within the “ABS” name, not just a marketing distinction [3].

Side-by-Side Comparison Table

Key Material Differences Explained

Chemical Structure and Polymer Family

Delrin is an acetal homopolymer. ABS is a different polymer family built from acrylonitrile, butadiene and styrene.

Within the acetal family itself, Celanese’s technical literature distinguishes homopolymer from copolymer: homopolymers like Delrin generally have somewhat better short term mechanical properties, while copolymers offer a wider processing window and better long term performance in hot water and certain chemical environments [12].

Strength and Load-Bearing Capacity

POM-H provides substantially higher tensile strength and heat deflection capability than representative CNC ABS. But tensile strength alone doesn’t determine whether a part survives impact, fatigue, creep, wear or chemical exposure.

The actual grade, temperature, geometry, stress concentration and loading duration still need to be evaluated.

Impact Resistance

Impact data produces nearly the opposite result from strength:

On ASTM D256 data specifically, standard ABS has roughly four to seven times the notched impact value of the various POM-H grades shown here, depending on which Delrin grade is the comparison point.

That doesn’t mean every ABS grade beats every Delrin grade, flame retardant ABS gives up nearly half its impact strength, and Delrin also offers toughened grades (500T, 100ST) specifically developed for better impact performance, though ASTM method Izod figures for those two weren’t published on the sheets reviewed [9] [6].

Engineering implication: if sudden impact is the dominant failure mode, standard POM-H should not be selected merely because its tensile strength is higher.

Wear and Friction Performance

POM has a long application history in sliding and wear components.

Protolabs lists gears, bearings, bushings and rollers among common acetal applications, describing it as an engineering thermoplastic for precision parts requiring high stiffness, low friction and dimensional stability [1].

Delrin 150’s own sheet reports a wear factor of 55 × 10⁻¹⁰ in³·min/ft·lb·hr under ASTM D3702 testing [10] — a concrete number rather than a generic “low friction” claim.

Dimensional Stability and Tolerance Capability

Dimensional stability shouldn’t be reduced to an unsupported claim like “Delrin always holds ±0.001 inch.” The achievable tolerance depends on machine capability, stock condition, geometry, thermal expansion, machining parameters, moisture, post-machining relaxation and inspection method, not the polymer name.

Delrin’s coefficient of linear thermal expansion is commonly cited around 4.7–6.8 × 10⁻⁵ in/in/°F for POM-H stock[1], broadly similar in order of magnitude to ABS’s.

The correct engineering statement is that Delrin/POM is attractive for precision mechanical parts because of its low moisture sensitivity and predictable behavior, but the achievable tolerance must still be established for the actual machining process and part geometry.

Moisture and Environmental Resistance

POM-H absorbs roughly 0.90% moisture at saturation on Protolabs’ sheet [1], low enough that it’s commonly specified where dimensional stability through humidity changes matters.

ABS also has relatively low moisture uptake compared with strongly hygroscopic polymers like nylon, but moisture absorption isn’t the same as chemical compatibility or dimensional stability under every environmental condition.

Chemical Resistance

Neither material should be treated as universally chemically resistant.

Celanese’s acetal guidance notes that copolymer acetal generally has improved resistance to hot water and alkaline environments compared with homopolymer acetal like Delrin[12].

ABS chemical resistance is also grade dependent and can be compromised by certain solvents, especially under stress.

The correct qualification for either material: check the exact resin grade against the actual chemical, concentration, temperature and exposure time, not a generic resistance chart.

UV Stability and Weathering

“ABS” and “Delrin” should each not be treated as having one outdoor weathering performance. Both families include specialized UV-stabilized and weatherable grades distinct from their standard formulations.

The correct outdoor comparison is between the actual weatherable grade on each side, using the manufacturer’s own weathering data.

Heat Resistance Comparison

The clearest numerical comparison available uses matched Protolabs data: POM-H lists 242–257°F heat deflection temperature at 264 psi, well above ABS’s figure of roughly 190°F found on a separate CNC ABS sheet [1] [11].

Delrin 150’s own sheet illustrates why the exact test load matters: its HDT is 257°F at the standard 264 psi load, but 336°F at a much lighter 66 psi load [10].

The same material, two very different-sounding numbers, depending only on how hard the test pushes on it. Any single “Delrin HDT” figure quoted without its test load should be treated as incomplete.

HDT itself should not be interpreted as a guaranteed continuous use temperature, it’s a standardized deformation-under-load measurement.

Actual service temperature depends on stress, duration, geometry, grade and environment.

Machining Comparison: CNC & Fabrication

Which Is Easier to Machine?

Both materials can be CNC machined.

Delrin tends to produce clean, predictable chips and is widely used for precision machined components [1] [12].

ABS machines successfully but needs attention to cutting heat, tool sharpness and chip evacuation to avoid smearing. See our detailed machining Delrin guide for parameters.

Tool Wear and Chip Formation

Machining behavior is affected by tool geometry, cutting speed, feed, depth of cut, coolant and part geometry.

Delrin’s stiffness and machinability make it widely used for machined precision components, but neither material should be assigned a universal tool life value. Optimize cutting conditions for the exact resin grade rather than assuming a fixed advantage either way.

Tolerance Control

Tolerance is a manufacturing capability, not an inherent material property. A “±0.001 inch is guaranteed” shouldn’t appear as a claim for either material.

Dimensional change can come from thermal expansion, moisture, residual stress and post machining relaxation, and the machine, tool, stock condition and inspection method all affect the final result.

Delrin can be a strong candidate for precision machined parts, but the actual tolerance must be validated through the machining process for the specific geometry.

Surface Finish

ABS is widely used where painting, gluing and cosmetic finishing matter. It accepts these directly.

Delrin’s low surface energy makes conventional adhesion and finishing more challenging without specialized treatment [12].

Choosing Between Delrin and ABS for Precision Components

For a precision mechanical component, work through the actual requirements rather than defaulting to the material with the higher tensile strength:

1. Tensile and compressive load.
2. Required stiffness.
3. Temperature, and at what load (see Heat Resistance Comparison above).
4. Friction and wear.
5. Impact loading.
6. Chemical exposure.
7. Moisture.
8. Dimensional tolerance.
9. Manufacturing process.
10. Required surface finish.

The data in this guide gives Delrin/POM-H a substantial advantage in tensile strength and HDT, and ABS a substantial advantage in notched impact strength, which one matters more depends entirely on which of the ten items above is the actual limiting requirement for the part.

Injection Molding Differences

Flow Characteristics

ABS is available in grades formulated for different flow requirements, including thin wall and high flow variants.

Delrin also has grades selected for flow and molding behavior, 900P, for instance, is specifically a low-viscosity grade intended for thin wall and multicavity molding rather than maximum strength [7].

Flow should be compared grade-to-grade, not as a blanket “ABS flows better” claim.

Shrinkage Rate

Delrin is semi crystalline, and its molding shrinkage is strongly influenced by crystallization, processing conditions and geometry.

ABS’s amorphous structure generally gives it lower, more predictable shrinkage.

Neither material has one universal shrinkage percentage worth publishing as a specification, it varies by grade and process, and should come from the resin manufacturer’s own molding guide.

Mold Complexity Capability

ABS’s flow characteristics and lower shrinkage make it a common choice for large, complex cosmetic housings.

Delrin can also be molded into complex parts, but the mold and process need to account for its crystallinity and shrinkage behavior.

The practical decision depends on wall thickness, flow length, shrinkage, draft, warpage, gate design, cooling and required surface finish.

Cycle Time and Production Cost

A fixed claim like “ABS always has a 15% shorter cycle time” isn’t defensible without a controlled process comparison.

Cycle time depends on mold temperature, melt temperature, wall thickness, cooling requirements, part geometry, grade and machine.

Treat any such percentage as something to verify for your own tooling, not a published fact to rely on.

Cost Comparison

Raw Material Cost

ABS is generally positioned as a lower cost engineering plastic.

Delrin’s broader grade portfolio (standard, lubricated, toughened, filled) spans a wider price range.

A universal $/kg figure would be misleading, since resin price moves with grade, supplier, order quantity, location, color, reinforcement, certification and market conditions.

Get a current quotation for the exact grade rather than relying on a published number.

Processing Cost

For CNC parts: material + machine time + tooling + labor + finishing + scrap/inspection.

For molded parts: resin + mold amortization + cycle time + machine cost + labor + finishing + scrap.

Delrin’s machinability can make it economically attractive for certain CNC parts, but there isn’t enough controlled, public evidence to claim a fixed percentage saving against ABS either way.

Long-Term Performance Value

This framework is more defensible than claiming either material universally has a lower total cost.

Application-Based Comparison

Gears and Mechanical Parts

Delrin/POM has a strong application case for gears and mechanical components, with Protolabs listing gears, bearings, bushings and rollers among common acetal applications [1].

ABS can be used for mechanical parts where impact resistance and cost matter more than wear performance, but the actual duty cycle should be evaluated rather than assumed.

Automotive Interior Components

ABS has a substantial automotive interior application base, where impact performance, flow, appearance and heat resistance can be balanced through grade selection.

Delrin can also appear in automotive mechanical components, linkages, small gears, fuel-system parts where strength, low friction or dimensional stability matter.

Electrical Housings

ABS is widely used for electrical and electronic housings because of its balance of impact resistance, stiffness, processability and finishing options.

Delrin can be appropriate for electrical/mechanical components needing its specific mechanical and dimensional properties, but the grade and electrical requirements (dielectric strength, flammability rating) need separate verification.

Consumer Product Casings

ABS has a strong case for consumer housings needing impact resistance, cosmetic appearance, paintability or bonding, and economical injection molding.

Delrin is generally the better fit when the casing also performs a demanding mechanical function rather than simply enclosing something.

When Delrin Is the Wrong Choice

1. You Need Easy Painting or Conventional Bonding

ABS accepts paint and adhesives directly.

Delrin’s low surface energy makes conventional bonding more challenging without specialized treatment [12].

If the primary requirement is a painted or conventionally bonded cosmetic enclosure, ABS is the more practical starting point.

2. The Environment Contains Aggressive Chemicals

Don’t assume Delrin resists every chemical, resistance depends on the exact polymer, grade, concentration, temperature and exposure duration.

Copolymer acetal generally outperforms Delrin’s homopolymer chemistry in hot water and alkaline conditions specifically [12].

3. Impact Toughness Is the Primary Requirement

Standard POM-H’s 1.0–2.0 ft-lb/in notched impact range sits well below ABS’s 7.7–8.0 [1] [2] [10].  

Standard POM-H shouldn’t be the default choice where high notched impact resistance is the dominant requirement.

Toughened Delrin grades exist (500T, 100ST); compare against the specific grade being considered, not generic Delrin.

4. The Part Is a Large, Complex Molded Geometry

Large or complex parts need flow length, wall thickness, shrinkage, warpage, gate location, cooling, mold temperature and grade viscosity evaluated together.

Both ABS and POM have specialized molding grades, so this is a process engineering decision, not a simple material “winner.”

5. The Application Requires Specialized Sterilization

Don’t assume a generic Delrin grade is automatically suitable for a medical sterilization process.

Verify the exact resin grade, sterilization method, temperature, exposure duration and required property retention against the supplier’s technical and regulatory documentation.

When ABS Is the Wrong Choice

1. High-Cycle Sliding or Wear

POM has a substantial grade portfolio built around low friction and wear, including lubricated and PTFE-filled variants [1] [12].

For continuously sliding or rotating parts, evaluate a suitable POM grade rather than assuming ABS is equivalent.

2. Long-Term Mechanical Loading

POM-H’s 10,500–11,000 psi tensile strength and higher modulus make it worth investigating for mechanically loaded precision components, particularly where stiffness and creep resistance matter [1].

The actual long term allowable stress still requires creep data at the operating temperature and stress level.

3. Aggressive Chemical Exposure

ABS chemical compatibility varies by grade and chemical. For demanding environments, check the exact ABS grade against the actual chemical and temperature rather than assuming generic resistance.

4. Demanding Outdoor Exposure

Standard ABS shouldn’t be treated as an outdoor grade material by default.

UV performance is grade-dependent, and a weatherable ABS grade should be compared against a weather-stabilized POM grade using actual weathering data.

5. High-Temperature Mechanical Service

At a comparable load, POM-H’s heat deflection temperature (242–257°F) runs well above the ABS figure found (~190°F) [1] [11].

If mechanical stiffness at elevated temperature matters, generic ABS shouldn’t be treated as equivalent to POM-H and HDT remains a comparative test property, not a continuous-use-temperature guarantee, for either material.

Frequently Asked Questions

Related Guides

•  Delrin® (POM): Properties, Grades, Applications & Material Selection Guide
• Delrin vs. Nylon A comparison where both materials genuinely compete for the same job.
• Delrin vs. Acetal (POM-H vs. POM-C) If the real question is which acetal grade, not a different polymer.
• UHMW vs. Delrin For wear duty cycles beyond what either material here covers well.
• Machining Delrin
• 3D Printing ABS
• PC ABS
• ABS Plastic Injection Molding
• Machining ABS
• Flame Retardant ABS

Technical sources

Values in this guide are attributed to the specific supplier sheet and grade they came from, reviewed September 2026.

Stock-shape sheets and injection-molding resin sheets report different values for the same nominal grade; verify the current datasheet before using a number for design, qualification or procurement.

[1] Protolabs — POM-H (Acetal Homopolymer) CNC material data sheet (2026)

[2] Protolabs — ABS CNC material data sheet (2026)

[3] Protolabs — ABS Natural and Black, including flame-retardant ABS, material data sheet

[4] UL Prospector / Protolabs — Delrin 500P NC010 (medium-viscosity homopolymer) technical data

[5] Material Data Center — Delrin 100 NC010 (high-viscosity homopolymer) datasheet

[6] Material Data Center — Delrin 100ST NC010 (super-toughened homopolymer) datasheet

[7] Plasticker — Delrin 900P NC010 (low-viscosity, thin-wall/multicavity) datasheet

[8] Entec Polymers — Delrin 900P NC-010 product data (notched Izod)

[9] Delrin 500T NC010 (toughened) ISO property data

[10] Trident Plastics — Delrin 150 NC010 (POM-H natural, extruded shapes, FDA/NSF grade) technical data

[11] ARRK — CNC ABS material data sheet (heat deflection, Vicat softening)

[12] Craftcloud — Delrin (POM-H) CNC material guide (surface energy, chemical limits)

Last reviewed: October 2026

Usama Ayub

Usama Ayub is the founder of PlasticSpec and a polymer manufacturing engineer with eight years of hands-on industrial experience in PET, PA6, and PA66 fiber and filament yarn production. He writes material property and selection guides for Delrin, Nylon, PEEK, PTFE, UHMW, Polycarbonate, and ABS.