What is Delrin made of?

Delrin is a polyoxymethylene homopolymer (POM-H) — a semi-crystalline engineering thermoplastic made by polymerizing formaldehyde. "Acetal" is the generic family name; Delrin is the brand name for the homopolymer grade. Acetal copolymer (POM-C) is a related material, typically made by copolymerizing trioxane with a small amount of comonomer.

Is Delrin the same as acetal?

Delrin is a type of acetal. Acetal is the generic material family (also called polyoxymethylene or POM). Delrin is the homopolymer variant; Acetron, Ertalyte and Sustarin are common copolymer or filled variants. Homopolymer (POM-H) is slightly harder and stiffer; copolymer (POM-C) resists hot water and weak bases better.

Several Delrin grades carry FDA food-contact and NSF compliance for repeated use. Food-contact status is grade-specific, not a property of "Delrin" in general — confirm the specific grade's regulatory listing before specifying it for food handling.

Can Delrin be machined?

Yes — POM-H is one of the most machinable plastics. It cuts cleanly on standard metalworking equipment, holds tight tolerances, and produces continuous chips. It is notably better than PEEK and most nylons for tolerance control because of its low moisture absorption and stiffness. Use sharp tooling, high rake angles, and avoid dwelling (heat buildup can melt the surface).

Delrin vs PEEK — which should I use?

Choose Delrin for stiff, dimensionally stable, low-cost mechanical parts up to about 85 °C continuous. Choose PEEK when service temperature exceeds 150 °C, when chemical resistance is required, or when the part must survive sterilization. PEEK costs roughly 8–12× more than Delrin, so for room-temperature mechanical parts Delrin is normally the better choice.

What is the melting point of Delrin?

175 °C (347 °F) — the crystalline melting point of acetal homopolymer. Note this is far above the maximum continuous service temperature of 85 °C (185 °F) and the deflection temperature of 125 °C at 1.8 MPa.

Delrin (Acetal / POM-H)

Complete property data sheet for Delrin acetal homopolymer — mechanical, thermal, electrical and physical values, each with its ASTM test method — plus grade selection (100 / 150 / 500) and comparison with PEEK, PTFE and Nylon.

Data verified 2026-09-29 · based on ASTM D6778-20

Mechanical Properties

Property	Metric	Imperial	Test method
Tensile strength, yield	75.8 MPa	11,000 psi	ASTM D638
Tensile modulus	3.10 GPa	450 ksi	ASTM D638
Elongation at break	25 %	25 %	ASTM D638
Flexural strength	110 MPa	16,000 psi	ASTM D790
Flexural modulus	2.90 GPa	420 ksi	ASTM D790
Compressive strength	35.9 MPa	5,200 psi	ASTM D695
Izod impact, unnotched	0.80 J/cm	1.5 ft·lb/in	ASTM D256
Hardness, Rockwell M	94	94	ASTM D785
Hardness, Rockwell R	120	120	ASTM D785
Coefficient of friction, dynamic	0.20	0.20	ASTM D3702
Limiting pressure-velocity (PV)	0.0513 MPa·m/s	1,460 psi·ft/min	ASTM D3702

Thermal Properties

Property	Metric	Imperial	Test method
Melting point	175 °C	347 °F	ASTM D2133
Deflection temperature @ 0.46 MPa (66 psi)	169 °C	336 °F	ASTM D648
Deflection temperature @ 1.8 MPa (264 psi)	125 °C	257 °F	ASTM D648
Max continuous service temperature, air	85 °C	185 °F	UL 746B
Max intermittent service temperature, air	149 °C	300 °F	—
Coefficient of linear thermal expansion	122 µm/m·°C	68 µin/in·°F	ASTM D696
Flammability	UL94 HB	UL94 HB	UL 94

Electrical & Physical Properties

Property	Metric	Imperial	Test method
Volume resistivity	1.00 × 10¹⁵ Ω·cm	—	ASTM D257
Dielectric strength	19.7 kV/mm	500 V/mil	ASTM D149
Dielectric constant @ 60 Hz	3.7	—	ASTM D150
Dissipation factor @ 60 Hz	0.0050	—	ASTM D150
Specific gravity / density	1.42 g/cm³	—	ASTM D792
Water absorption, 24 h	0.25 %	—	ASTM D570
Water absorption at saturation	0.90 %	—	ASTM D570

Delrin 100 vs 150 vs 500

Delrin 100, 150 and 500 are the same chemistry at different melt-flow grades. The number indicates melt viscosity, not a performance tier — so 500 is not "better" than 100.

Grade	Melt flow	Molecular weight	Best for
Delrin 100	Lowest flow	Highest	Maximum toughness and impact strength, thick sections, stock shapes (rod, sheet)
Delrin 150	Medium flow	Medium	General-purpose molding and machining — the most widely available grade
Delrin 500	Highest flow	Lowest	Thin-wall and complex molds; best moldability

Practical difference: bulk mechanical properties (tensile, flexural, density, melting point) are essentially equivalent across 100 / 150 / 500. The difference shows up in impact strength (100 is toughest) and moldability (500 is easiest). For machined parts, choose by stock availability — 150 is the default.

Delrin vs PEEK vs PTFE vs Nylon

Property	Property	Delrin (POM-H)	Nylon 6/6	PEEK
Density (g/cm³)	1.42	1.14	1.30	2.16
Tensile strength (MPa)	75.8	82.7	100	20–35
Melting point (°C)	175	265	343	327
Max continuous use (°C)	85	105	250	260
Water absorption, 24 h (%)	0.25	1.2–1.5	0.15	0.01
Coefficient of friction	0.20	0.25–0.40	0.34	0.04–0.10
Machinability	Excellent	Good	Fair	Excellent
Relative cost	1×	1×	8–12×	3–5×

Comparison values are typical published figures for unfilled grades. How to choose: Delrin for stiff, dimensionally stable, low-cost mechanical parts at moderate temperature; Nylon where toughness and higher temperature matter and moisture swelling is acceptable; PEEK for high temperature or chemical exposure where cost is secondary; PTFE where the lowest possible friction or chemical inertness is the priority.

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Frequently Asked Questions

What is Delrin made of?: Delrin is a polyoxymethylene homopolymer (POM-H) — a semi-crystalline engineering thermoplastic made by polymerizing formaldehyde. "Acetal" is the generic family name; Delrin is the brand name for the homopolymer grade. Acetal copolymer (POM-C) is a related material, typically made by copolymerizing trioxane with a small amount of comonomer.
Is Delrin the same as acetal?: Delrin is a type of acetal. Acetal is the generic material family (also called polyoxymethylene or POM). Delrin is the homopolymer variant; Acetron, Ertalyte and Sustarin are common copolymer or filled variants. Homopolymer (POM-H) is slightly harder and stiffer; copolymer (POM-C) resists hot water and weak bases better.
Is Delrin food safe?: Several Delrin grades carry FDA food-contact and NSF compliance for repeated use. Food-contact status is grade-specific, not a property of "Delrin" in general — confirm the specific grade's regulatory listing before specifying it for food handling.
Can Delrin be machined?: Yes — POM-H is one of the most machinable plastics. It cuts cleanly on standard metalworking equipment, holds tight tolerances, and produces continuous chips. It is notably better than PEEK and most nylons for tolerance control because of its low moisture absorption and stiffness. Use sharp tooling, high rake angles, and avoid dwelling (heat buildup can melt the surface).
Delrin vs PEEK — which should I use?: Choose Delrin for stiff, dimensionally stable, low-cost mechanical parts up to about 85 °C continuous. Choose PEEK when service temperature exceeds 150 °C, when chemical resistance is required, or when the part must survive sterilization. PEEK costs roughly 8–12× more than Delrin, so for room-temperature mechanical parts Delrin is normally the better choice.
What is the melting point of Delrin?: 175 °C (347 °F) — the crystalline melting point of acetal homopolymer. Note this is far above the maximum continuous service temperature of 85 °C (185 °F) and the deflection temperature of 125 °C at 1.8 MPa.

Value Sources

Each data column on this page is tied to the source it came from. The numbers in square brackets correspond to the table headers above.

#	Source	Type	Revision / method
[1]	Delrin 150 published material data sheet	standard	supplier data sheet, retrieved 2026-09 — source

Data Sources

Standard	Revision	What it covers on this page
ASTM D6778 — Standard Classification System for Polyoxymethylene Molding and Extrusion Materials	ASTM D6778-20	classification of acetal homopolymer and copolymer grades
Individual ASTM test methods	current revisions as of 2024 (methods cited per property)	each mechanical, thermal and electrical property value

Cross-checked against:

Glemco published Delrin 150 material data sheet
Supplier-published POM-H data sheets (values consistent)

Values are typical published figures for the grade stated. Property data for filled or modified grades differs substantially — use the specific grade data sheet for design work.

Accuracy and use. The values on this page are compiled from the published standards and cross-checked sources listed above. Where values are derived, the derivation is stated. No warranty, express or implied, is made as to the accuracy or completeness of this information, and no liability is accepted for any loss or damage arising from its use. Engineering reference data is provided for guidance in preliminary work — before a value is used for design, fabrication or acceptance testing, verify it against the current revision of the governing standard and against your own inspection. The user assumes all risk and responsibility in connection with the use of this information.

Cite This Page

Every value on this page is traceable to the sources listed above. If you use the data in a document, paper or report, cite it as:

Plain text

Engineering Reference. "Delrin (Acetal / POM-H) Properties." https://refmanual.com/materials/delrin-150/ (accessed 2026-09-29). Data from ASTM D6778 — Standard Classification System for Polyoxymethylene Molding and Extrusion Materials, ASTM D6778-20.

BibTeX

@misc{delrin-150,
  title        = {Delrin (Acetal / POM-H) Properties},
  author       = {{Engineering Reference}},
  howpublished = {\url{https://refmanual.com/materials/delrin-150/}},
  note         = {Accessed: 2026-09-29},
  source       = {ASTM D6778 — Standard Classification System for Polyoxymethylene Molding and Extrusion Materials, ASTM D6778-20}
}

RIS (EndNote, Zotero, Mendeley)

TY  - ELEC
TI  - Delrin (Acetal / POM-H) Properties
AU  - Engineering Reference
PB  - Engineering Reference
UR  - https://refmanual.com/materials/delrin-150/
PY  - 2026
DA  - 2026-09-29
N1  - Source: ASTM D6778 — Standard Classification System for Polyoxymethylene Molding and Extrusion Materials, ASTM D6778-20
ER  -

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