Delrin Tube — OD/ID Sizes, Tolerances & Ordering (POM-H)
Delrin tube is extruded acetal homopolymer (POM-H) with a concentric through-bore, produced in standard OD/ID combinations. Tube is the cost-effective starting point when the final part has a hollow geometry and boring the ID from solid rod would waste significant material. Common applications include bushings, sleeves, spacer tubes, and cylindrical housing components.
At a glance:
- OD range stocked: 0.500" through 8.0" OD (wall thickness varies by size)
- Standard length: 4 ft
- Tolerance on OD: ±0.015"–0.030" depending on size
- Tolerance on wall thickness: ±10% of wall per ASTM D6100
- Grade: Delrin 150 natural is the primary stocked tube grade
- Primary keyword: "delrin tube" — US volume 100/month
When to Use Tube vs. Boring from Solid Rod
Delrin tube is the right choice when:
- The through-bore is large relative to the OD — boring a 3" ID in a 3.5" OD part from solid 3.5" rod wastes 72% of the material by volume; starting from tube with a matching wall saves cost
- Multiple identical hollow parts are needed — tube stock eliminates the boring operation entirely for simple sleeves and bushings
- Bore concentricity to OD is needed at the stock level — extruded tube concentricity is adequate for many bushing applications without boring
Solid rod is preferred when:
- The bore is small relative to the OD (economical to bore)
- The ID tolerance is tighter than tube can provide as-extruded (finish bore from solid)
- The geometry has non-concentric features requiring turning from a solid blank
Standard Stocked Delrin Tube Sizes
| OD | Wall Thickness | ID (approx.) | OD Tolerance | Standard Length |
|---|---|---|---|---|
| 0.500" | 0.062" | 0.376" | ±0.015" | 4 ft |
| 0.625" | 0.062" | 0.501" | ±0.015" | 4 ft |
| 0.750" | 0.062" | 0.626" | ±0.015" | 4 ft |
| 1.000" | 0.125" | 0.750" | ±0.015" | 4 ft |
| 1.000" | 0.250" | 0.500" | ±0.015" | 4 ft |
| 1.250" | 0.125" | 1.000" | ±0.020" | 4 ft |
| 1.500" | 0.125" | 1.250" | ±0.020" | 4 ft |
| 1.500" | 0.250" | 1.000" | ±0.020" | 4 ft |
| 2.000" | 0.125" | 1.750" | ±0.020" | 4 ft |
| 2.000" | 0.250" | 1.500" | ±0.020" | 4 ft |
| 2.000" | 0.375" | 1.250" | ±0.020" | 4 ft |
| 2.500" | 0.250" | 2.000" | ±0.025" | 4 ft |
| 3.000" | 0.250" | 2.500" | ±0.025" | 4 ft |
| 3.000" | 0.375" | 2.250" | ±0.025" | 4 ft |
| 4.000" | 0.375" | 3.250" | ±0.030" | 4 ft |
| 4.000" | 0.500" | 3.000" | ±0.030" | 4 ft |
| 6.000" | 0.500" | 5.000" | ±0.030" | 4 ft |
Custom OD/wall combinations are available to special order; minimum quantities apply. Non-standard sizes may require lead time.
In Delrin (POM-H) tube, the centerline porosity concern present in large-diameter solid rod is mitigated by the hollow cross-section — the through-bore removes the core material. However, for tube with very thick walls (wall > 30% of OD), some porosity can still develop in the mid-wall zone during extrusion. For thick-wall tube applications requiring uniform cross-section, evaluate acetal copolymer tube, which avoids POM-H porosity regardless of wall thickness.
Tolerances and Dimensional Notes
OD tolerance: As tabulated above; ±0.015"–0.030" per ASTM D6100 for standard sizes.
ID tolerance: ID is determined by OD minus 2× wall; individual tolerance on ID is ±15% of wall thickness for standard extruded tube.
Concentricity (wall variation): Standard extruded tube has wall variation of ±15% of nominal wall. For precision bore concentricity (eccentricity < 0.005" TIR), finish bore the ID after procurement.
Straightness: Standard tube is straight within 0.050"/ft; precision-straightened to 0.010"/ft available on request.
Machining Delrin Tube
Tube is typically chucked on the OD for end-face operations and internal boring. For thin-wall tube, use an expanding mandrel or soft-jaw chuck to distribute clamping load and prevent distortion. Turning parameters are the same as for solid Delrin rod — see the Delrin machining guide.
For cutting tube to length in the machine shop:
- Bandsaw or cutoff tool on a lathe both work well
- Deburr the cut ends; Delrin cuts cleanly but may have a slight raised burr at the parting line
Applications for Delrin Tube
Bushing and sleeve blanks: Tube provides the hollow starting point; finish-bore to final tolerance.
Spacer tubes: Fixed-length tube sections as spacers in bolted assemblies, guide assemblies, and optical mounts.
Structural support tubes: In lightweight mechanical assemblies where a hollow cross-section provides required stiffness at lower weight and cost than solid rod.
Valve spool sleeves: Delrin tube sections as bearing sleeves for valve spools in hydraulic and pneumatic control valves.
Bearing housings: Tube machined into a housing with an o-ring groove and flange, used as a bearing housing or seal bore in light-duty assemblies.
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