Plastic Tube & Hollow Rod: Sizes, Materials & Bore Tolerances

Plastic tube stock — also called hollow rod — is pre-bored cylindrical form supplied with a defined inside diameter (ID), outside diameter (OD), and wall thickness. Starting with tube instead of solid rod eliminates the lathe boring operation when producing bushings, sleeves, spacers, and guide cylinders. Cast and extruded tube is stocked in Nylon, Acetal, PEEK, UHMW-PE, PVDF, PTFE, and phenolics, with standard ID/OD combinations ranging from 3/4" OD up to 24" OD in select materials.

TL;DR

• Tube is specified by OD × ID (or OD × wall thickness); verify both dimensions with your distributor
• Cast Nylon tube dominates the large-diameter bushing and wear-sleeve market (up to 24" OD)
• PTFE tube provides near-universal chemical resistance with low friction for fluid-handling and liner applications
• PEEK tube is available to ~6" OD for high-temperature and semiconductor applications
• Bore (ID) tolerances vary 2–4× more than solid rod OD tolerances; specify if bore will be used as-machined or finish-bored
• Common wall thicknesses: 1/8", 1/4", 3/8", 1/2", and 3/4"
• Tube is sold by the foot or cut to length; standard lengths are 2 ft

Common ID/OD Table by Material

Non-standard wall thicknesses and bore diameters are produced by CNC boring solid rod or turning OD/ID to specification — see machined parts.

Materials Available in Tube

Nylon Tube

Nylon tube is the most widely stocked plastic hollow rod. Cast Nylon 6 tube reaches up to 24" OD and is the standard material for large machinery bushings, conveyor sleeve bearings, and slow-rotating journals that would otherwise require bronze. Natural Nylon tube is FDA-compliant for incidental food contact. MoS₂-filled Nylon tube (gray) adds self-lubrication and is widely used in dry-running bearing applications where re-lubrication is difficult. Moisture absorption is significant — allow 0.006"–0.010" per inch of wall thickness for post-installation swell when operating in wet environments.

Extruded Nylon 6/6 tube is available in smaller OD ranges (3/4"–6") with tighter dimensional tolerances and lower moisture absorption than cast Nylon 6. For applications with close ID fits (H7 or tighter), specify extruded Nylon 6/6 and finish-bore to size after installation.

Acetal Tube

Acetal hollow rod is the premium bushing material in the 3/4"–6" OD range. Its near-zero moisture absorption (0.25% saturation) means the bore diameter is stable from dry to wet conditions — a critical advantage over Nylon in precision fits. Acetal tube is white (natural) or black; FDA-compliant grades are stocked in natural. Self-lubricating Acetal grades with PTFE or silicone additives are available for lower-friction service. Tensile strength: 9,500–10,000 psi; compressive strength: 18,000 psi — sufficient for most bushing loads.

PEEK Tube

PEEK tube handles continuous temperatures to 480°F (250°C) and resists hydraulic fluids, fuels, and most organic solvents. Available in natural and 30% glass-filled grades from 1/2" to 6" OD. Extruded PEEK tube is used in semiconductor wafer-handling arm sockets, medical device spacers and bearings, and aerospace fluid-system components. Its combination of high strength (14,500 psi tensile) and chemical resistance is unmatched among extruded thermoplastic tubes.

UHMW-PE Tube

UHMW-PE tube delivers outstanding abrasion resistance for wear sleeve and guide bushing applications where impact loading is present. Ram-extruded in OD from 1-1/2" to 10". The near-zero water absorption ensures dimensional consistency even in immersed applications. UHMW-PE tube is used for trough-liner pipe sleeves, star-wheel guides, and chain conveyor pins. Not recommended for precision fits because OD/ID tolerances on ram-extruded tube are looser than standard extruded materials.

PTFE Tube

PTFE tube provides near-universal chemical resistance and the lowest friction of any solid material (dynamic COF ≈ 0.05 against steel). Compression-molded from sintered powder in OD from 1/4" to 12". PTFE tube is used as valve stem liners, fluid transfer line inner sleeves, and electrical insulation. The high creep rate of PTFE under compressive load limits its structural use — PTFE tube is typically a liner inside a metal housing, not a load-bearing structural component.

PVDF Tube

PVDF (Kynar) tube handles acids, bases, and oxidizing media that degrade most engineering plastics. Continuous service to 275°F (135°C) and UL94 V-0 flame rating make it the standard choice for semiconductor chemical delivery systems and high-purity water plumbing. Extruded from 1/2" to 4" OD in standard schedule dimensions.

Phenolic and PPS Tube

Cotton phenolic tube (NEMA LE) provides high compressive strength (~35,000 psi) and dimensional stability for precision bearing races and rollers. PPS (Ryton) tube in 40% glass-filled grade offers near-zero moisture absorption and excellent chemical resistance for tube-in-shell heat exchanger bodies and pump sleeves.

How Plastic Tube Is Made

Extrusion

Extruded tube is produced by a screw extruder feeding through an annular die with a pin mandrel setting the bore. The tube is pulled through a vacuum sizing tank that fixes the OD, while the mandrel controls the ID. For small and medium ODs (up to ~6"), extrusion produces consistent wall thickness and reasonable bore concentricity. Tolerances on extruded tube: OD ±0.010"–±0.025"; ID ±0.020"–±0.040"; wall thickness ±15% of nominal wall.

Ram Extrusion

UHMW-PE tube is ram-extruded because its high molecular weight prevents screw processing. A hydraulic ram forces compacted powder through a heated annular die, producing tube of consistent density. OD/ID tolerances on ram-extruded UHMW tube are wider than conventional extrusion — plan to finish-bore and turn OD for precision applications.

Casting

Cast Nylon 6 tube is produced by anionic polymerization of caprolactam in an annular mold (a rotating outer shell with a central mandrel). This process is the only viable route for large-diameter tube up to 24" OD because the heat generated during polymerization is managed more easily in a large casting than through a die. Cast tube has isotropic properties and lower residual stress than extruded; wall thickness uniformity is ±5%–10% on large castings.

Molded and Sintered

PTFE tube is compression-molded from powder and sintered. Phenolic tube is molded from resin-impregnated fabric in a stepped-mandrel press. Both processes produce dense, void-free material with excellent consistency.

Specifications & Tolerances

Bore (ID) Tolerances

Concentricity

Extruded tube typically holds TIR concentricity within 0.005"–0.015" OD to ID. Cast Nylon tube may show 0.020"–0.050" TIR on larger diameters due to mold core shift. Finish-turned OD or finish-bored ID reduces TIR to 0.001"–0.003" on a CNC lathe.

Cutting & Finishing

Cutoff and Parting

Tube is parted on a horizontal band saw or cold saw with a fine-tooth blade (14–18 TPI for thin-wall, 10–14 TPI for thick-wall). Support the tube close to the cut to avoid collapse of thin walls. For small-wall tube, a V-block fixture prevents elliptical deformation under saw pressure.

Finish Boring

For precision ID fits, mount tube in a 4-jaw chuck, bore to final diameter with a single-point boring bar, and ream if necessary. Boring removes the as-extruded ovality and achieves roundness within 0.001"–0.002". For Nylon tube, allow for moisture growth after installation in wet environments — finish-bore slightly undersize and allow to equilibrate.

OD Turning

OD turning brings the outer surface to a precise cylinder and improves concentricity. Support with a live center in the bore or a mandrel. Light finishing cuts (0.005"–0.015") at 400–800 SFM produce 32–63 µin Ra surfaces without heat buildup.

More related guides

Common materials and applications stocked in this form:

Top materials

• PEEK
• UHMW
• Delrin
• G10 and FR4

Applications

• Bushings & bearings
• Wear strips & guide rails
• Electrical insulation

Industries

• Aerospace plastics
• Food & beverage plastics
• General industrial