Precision Transmission
Sleeves & Spacers

A precision transmission sleeve is a thin-wall cylindrical part with a precisely ground bore and OD, used to adapt between shaft and housing diameters in gearboxes, servo drives, and bearing assemblies. Common uses: adapting a Ø20 mm motor shaft to a Ø25 mm gearbox input bore; spacing bearings axially in a housing; providing a hardened wear surface for a housing bore. The critical parameters are bore diameter, OD, concentricity between bore and OD, surface finish, and length.

HXC achieves bore-to-OD concentricity of ±0.003 mm TIR as standard on precision transmission sleeves, by grinding bore and OD in the same setup without re-chucking. Tighter concentricity (±0.001 mm) is available for precision spindle and encoder applications at additional cost and longer lead time.

42CrMo4 through-hardened: gearbox and machine tool sleeves — wear-resistant, dimensionally stable. Al 7075-T6 anodized: lightweight robot joint adapters. SUS316L passivated: medical and food applications. Ti Grade 5: aerospace weight savings. C45 + hard chrome: machine tool spindle sleeves requiring a hardened wear surface.

Minimum practical wall thickness for a precision ground sleeve: 1.0 mm for stainless and steel; 1.5 mm for aluminium (thinner walls distort during anodizing). Below 1 mm, the sleeve becomes too flexible to hold roundness during grinding. For very thin-wall applications, electrolytic nickel or hard chrome on a thicker sleeve is often a better approach than machining a very thin precision sleeve.

Standard: Ra 0.4 µm on ground OD and bore surfaces. For bearing press fits: Ra 0.8 µm OD (rougher promotes consistent interference fit). For encoder shaft interfaces: Ra 0.2 µm (smoother reduces runout contribution from surface texture). For hard chrome spindle sleeves: Ra 0.1–0.2 µm after chrome grinding.

For pressed-in (fixed) bearing outer race: OD tolerance P6 or P7 (slight interference). For rotating outer race housings: OD tolerance H7 (sliding clearance). Bore tolerances for inner race installation depend on bearing inner diameter — typically k5 or m5 for fixed inner race fits. Always specify the bearing designation and fit class on the drawing; HXC engineers confirm the correct sleeve dimensions from the bearing manufacturer's data.

Yes — HXC regularly machines precision sleeves with integrated keyways, tapped holes, oil grooves, snap-ring grooves, and flange faces. All features are completed in one 5-axis setup to maintain concentricity. Examples: a transmission sleeve with a keyway bore and oil distribution groove; a bearing adapter sleeve with a locking thread and integrated thrust flange.

Prototype (1–5 pcs, turned + ground): 4–7 days. Small batch (20–100 pcs): 7–12 days. Production (200–2,000 pcs): 10–16 days. Hard chrome sleeves: add 3–5 days. Stainless or titanium: add 2–3 days.