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Delrin vs nylon? The question comes up for gears, bushings, structural brackets, wear pads, and any part that slides, seals, or takes a load.
This comparison covers moisture behavior, dimensional stability, mechanical properties, machinability, tolerances, and application fit: the dimensions that determine which material belongs on your drawing.
What Are Delrin and Nylon?
Delrin is acetal homopolymer (POM-H). It belongs to the polyoxymethylene (POM) family alongside acetal copolymer (POM-C). POM-H has slightly higher crystallinity and stiffness; POM-C offers better resistance to hot water and alkalis. The distinction matters if your part will see aggressive cleaning agents or steam.
Nylon covers the polyamide (PA) family. PA6 and PA66 are the two workhorse grades for machined parts. PA6 absorbs more moisture but machines more easily. PA66 has higher strength and heat resistance but is less forgiving during machining. Glass-filled variants (PA6-GF30, PA66-GF30) boost stiffness and HDT at the cost of increased tool wear.
Both are semi-crystalline thermoplastics available in sheet, rod, and tube. Both machine on standard CNC mills and lathes. Both get specified for the same part types, which is why the comparison comes up repeatedly.
For a broader look at machining engineering plastics, see our plastic CNC machining overview.
Quick Comparison Table
Figures assume dry-as-machined conditions. Moisture and temperature shift these numbers; those effects are covered in the following sections.
| Property | Delrin (POM-H) | Nylon (PA6, dry) | Notes |
| Density (g/cm³) | 1.41–1.45 | 1.13–1.35 | Nylon ~7% lighter |
| Tensile strength (MPa) | 68–70 | 82–85 | Nylon stronger in tension when dry |
| Flexural modulus (MPa) | ~3,000 | ~2,800 | Delrin stiffer in bending |
| Moisture absorption (24h, %) | 0.2 | 1.5–2.5 | Root cause of most behavioral differences |
| Moisture absorption (equilibrium, %) | <0.8 | 7–9 (PA6) / 2.5 (PA66) | PA6 absorbs 3x more than PA66 at saturation |
| CoF (dry, vs steel) | 0.20–0.35 | 0.30–0.40 | Delrin slides better without lubrication |
| HDT at 1.8 MPa (°C) | ~95 | ~75–85 (PA66) | Delrin holds shape better under load at temperature |
| Continuous service temp (°C) | ~90 | ~120 (PA66) | Nylon handles higher ambient heat long-term |
| Raw material cost | $ | $–$$ | Standard grades comparable; filled/specialty grades push nylon higher |
| CNC machinability | Excellent | Good (requires pre-drying) | Delrin more forgiving for tight tolerances |
Nylon looks stronger on paper, but that paper assumes a dry lab. In a workshop or end-use environment, moisture changes the comparison.
Delrin vs Nylon: Moisture and Stability
Nylon is hygroscopic. PA6 absorbs 7–9% of its weight in moisture at saturation; PA66 around 2.5%. Delrin stays below 0.8% at full saturation and absorbs slowly, remaining dimensionally stable through typical humidity swings.
A 100 mm nylon part machined bone-dry can grow 0.3–0.9 mm after weeks in a humid environment. A part delivered at ±0.05 mm may no longer fit. The growth is rarely uniform: thick sections swell more than thin walls, and clearance fits can close unpredictably.
Delrin’s moisture uptake is low enough that dimensional change is negligible in most non-immersion applications. This is why Delrin is the default for precision sliding fits, bearing journals, and anything where clearance is measured in hundredths.
Conditioning nylon
Conditioning (controlled moisture exposure, typically water immersion or humid aging) brings the part to equilibrium before delivery. It is standard practice for bearing-grade PA66. It reduces dimensional variation and makes behavior more predictable, but the part still expands and contracts with ambient humidity. Conditioning does not make nylon behave like Delrin.
What operators report
Nylon feels gummy during cutting, especially if stock has been stored without climate control. Delrin cuts clean and predictable off the shelf. Damp nylon deflects differently under the tool, swarf clears poorly, and burr formation is more common.
See our nylon CNC machining guide for detailed processing parameters.
Delrin vs Nylon: Strength, Wear, and Load Behavior
Tensile and stiffness
Dry PA6: 82–85 MPa tensile. Delrin: 68–70 MPa. But nylon loses 10–20% of tensile strength after conditioning. A PA6 part machined at 82 MPa may stabilize at 65–70 MPa after moisture equilibration, right where Delrin already sits.
In bending, Delrin is stiffer (~3,000 MPa flexural modulus vs ~2,800 MPa for unreinforced nylon). For gear teeth, this means less deformation and more accurate motion transmission. For bushings under radial load, less bore distortion over time.
Fatigue
Delrin outperforms nylon in cyclic loading. Its polymer chain structure handles repeated stress cycles without the progressive softening that moisture-affected nylon shows. Relevant for gears, cams, and parts seeing millions of load cycles.
Wear and friction
Delrin vs steel, dry: CoF 0.20–0.35. Nylon: 0.30–0.40. Delrin parts often run dry where nylon would need external lubrication.
PTFE-filled Delrin (Delrin 100AF) drops CoF toward 0.10. Used for bearings, seals, and sliding elements where external lubrication is undesirable.
Real-world data: on EV drivetrain forums, nylon reduction-drive gears developed pitting and noise over time; Delrin replacements ran quieter with less wear. On automotive forums, Delrin suspension bushings accumulated 20,000+ miles with no measurable bore wear, running smoother than the OEM metal-backed parts they replaced.
Impact
Nylon absorbs more energy before fracture. The better choice for clips, snap-fits, and parts that may see accidental impact. Delrin is notch-sensitive: a sharp corner or sudden load concentrates stress and initiates a crack.
Delrin vs Nylon: CNC Machining and Tolerances
Delrin machining
Cuts dry, clean chips, holds dimensions without stress relief. Surface finish Ra 0.8–1.6 μm is routine with sharp carbide. Standard tolerance ±0.05 mm is straightforward. ±0.01–0.02 mm achievable on dimensional features with attention to tool condition and fixturing. Does not gum up cutters. Rarely needs coolant.
Thin-walled POM features introduce a different challenge: vibration and tool deflection can cause surface chatter and tolerance drift. We have machined locating plates with a narrow central web where step-controlled roughing and finishing passes held all critical features within 0.1 mm. The limiting factor was geometry rigidity, not material machinability.
Nylon machining
Requires pre-drying (24–48 hours at ~80°C). Less rigid under the tool: light cuts and sharp positive-rake tooling needed to control deflection and burrs. Standard tolerance around ±0.10 mm. ±0.05 mm requires careful stock prep and process sequencing (rough, stabilize, finish). ±0.025 mm needs PA66 or glass-filled grades, pre-conditioned stock, and acceptance that final dimensions drift with ambient humidity.
For nylon parts that need these process controls, our nylon CNC machining services cover material prep through final inspection.
Choosing Delrin vs Nylon by Application
Gears
Delrin: low backlash, quiet operation, consistent tooth geometry over part life. Go-to for instrument gears, encoder wheels, timing pulleys, and light-to-medium power transmission.
Nylon: shock loads, start-stop cycling, lubricated enclosures where moisture absorption is less of a concern. Toughness handles abuse that would crack an acetal gear.
For AGMA Q7–Q9 precision gears, Delrin’s ability to hold machined tooth profile without post-machining growth often makes it the only viable choice short of metal.
Bushings and bearings
Delrin: dry-running plain bearings, linear guides, any surface where stick-slip matters. Low CoF and hardness keep the bearing surface smooth over wear life. PTFE-filled grades extend this further.
Nylon: environments with abrasive contamination. Its surface can embed hard particles rather than letting them score the shaft. Side bearings are one such application. Oil-filled nylon (PA6 with internal lubricant) performs well in dirty, intermittently lubricated conditions.
Structural and housing parts
Nylon: brackets, enclosures, structural parts where impact resistance outweighs micron-level precision. Glass-filled nylon (PA6-GF30) bridges the stiffness gap with Delrin while retaining toughness.
Delrin: precision structural parts where creep resistance and long-term dimensional stability are critical: sensor mounts, alignment fixtures, optical bench components.
By industry
| Industry | Delrin | Nylon |
| Medical | Fluid path components, instrument gears, valve bodies (low extractables, chemical resistance to sterilants) | Equipment housings, structural brackets, impact-resistant fixtures |
| Semiconductor | Wafer handling, cleanroom fixturing, thermode insulators (low particle generation, minimal outgassing, thermal stability) | Less common; moisture absorption risks contamination in dry-room environments |
| Automotive | Fuel system components, window regulator gears, seat track bushings (dimensional stability across temperature swings) | Under-hood parts, cable ties, engine covers (PA66-GF for heat; PA6 for cost-sensitive interiors) |
| Robotics | Joint bushings, sliding elements, end-effector precision parts (low friction, no stick-slip) | Impact-absorbing bumpers, cable management, structural brackets (toughness and fatigue resistance) |
Decision Checklist
Will the part see moisture or humidity in service?
Yes: Delrin. A nylon part may pass inspection at 40% RH and fail fit-check at 70% RH.
What tolerance does the drawing require?
±0.05 mm or tighter: Delrin is the lower-risk choice. Nylon can reach these tolerances, but holding them through shipping, storage, and end-use humidity adds cost and lead time.
Static, cyclic, or impact load?
Static: either. Choose by tolerance and environment. Cyclic: Delrin for fatigue life; nylon where some compliance is beneficial. Impact: Nylon. Delrin is stiff but notch-sensitive.
Is low friction critical? Can the part be lubricated?
Critical, cannot lubricate: Delrin (or PTFE-filled Delrin). Critical, can lubricate: either, but Delrin has a better baseline CoF. Not critical, cannot lubricate: Delrin.
What does failure cost?
Standard-grade material cost differences are single-digit percentages. The real variable in material selection is the cost of field failure.
| Material | Cost tier |
| Standard POM (copolymer/homopolymer) | $ |
| Standard PA6 | $ |
| PA66 (natural or black) | $$ |
| Glass-filled nylon (PA6-GF30, PA66-GF) | $$ |
| PTFE-filled Delrin (POM 100AF) | $$$ |
Still weighing Delrin against nylon? Your application drives the material choice. Upload your drawing and our engineers will verify the grade selection against your load, moisture, and tolerance targets before quoting.
Frequently Asked Questions
Is Delrin stronger than nylon?
Nylon has higher tensile strength when dry (82–85 vs 68–70 MPa). Delrin is stiffer (higher flexural modulus) and holds its strength in humid environments. Nylon’s tensile advantage shrinks or disappears after moisture conditioning.
Is Delrin the same as acetal or POM?
Not exactly. “Acetal” and “POM” are two names for the same polymer family. “Delrin” is DuPont‘s brand name, technically referring to acetal homopolymer (POM-H). In practice, engineers use “Delrin” to mean any POM grade.
Can you 3D print Delrin and nylon?
Nylon: yes. SLS and MJF produce functional parts. FDM works on enclosed machines with thoroughly dried filament, though large parts tend to warp.
Delrin: no. FDM warps heavily, layers delaminate, and melting releases formaldehyde. SLS-grade POM powder exists but is rare outside specialized bureaus.
Bottom line: if your workflow needs both 3D-printed prototypes and CNC-machined production parts in the same material, nylon is the only option.
Which costs more, Delrin or nylon?
Standard PA6 and standard POM are both in the $ tier: nearly identical by weight. PA66 costs about twice as much as PA6. Glass-filled nylon and PTFE-filled Delrin (POM 100AF) push into $$$ territory. The per-kilogram price difference is rarely the deciding factor. A material saving that looks attractive on a BOM line becomes expensive when a part swells and fails inspection after shipping.
