Concentric Adapter
High-Precision Sleeves

A high-precision sleeve is a short cylindrical part with a precision-ground bore and OD used to adapt between shaft and housing diameters, or to serve as a bearing carrier. The critical parameter is bore-to-OD concentricity — any eccentricity between bore and OD adds directly to the shaft runout of the assembly. HXC achieves ±0.003 mm concentricity by grinding the OD from the finished bore as datum in one setup.

An adapter sleeve converts a shaft OD to a different housing bore — for example, mounting a Ø40 mm bearing onto a Ø35 mm shaft. A reduction sleeve (reducer bushing) converts a motor shaft to a smaller coupling bore. Both use the same manufacturing approach but the fit directions differ: the adapter sleeve has an interference OD and clearance bore; the reduction sleeve has a clearance OD and clamped bore. HXC makes both.

The adapter sleeve OD fits into the bearing bore with p5 or r5 interference (same as a direct shaft-to-bearing fit) — the sleeve transmits radial load from the shaft to the bearing. The sleeve bore fits the shaft with H7/h6 clearance (fixed by set-screw or locking nut). If concentricity between sleeve OD and bore is poor, the bearing runs eccentric on the shaft — causing vibration and reduced bearing life.

Internal grinding leaves a subtle three-lobe or five-lobe pattern from the grinding wheel contact. For a sleeve that runs directly on a shaft or carries a bearing in the bore, this lobing causes uneven contact and localised wear. Honing removes the lobing, producing a true-round bore (roundness ≤ 0.002 mm) with a cross-hatch finish that retains lubricant. HXC hones sleeve bores to IT4–IT5 on precision orders.

Prototype (1–5 pcs, turned + ground + honed): 4–7 days. Small batch (10–50 pcs): 7–12 days. Production (100–1,000 pcs): 10–16 days. Stainless or titanium: add 2–4 days. Rush production available.

42CrMo4 (induction hardened) — standard adapter sleeves. GCr15 (SUJ2) through-hardened — bearing carrier sleeves. SUS303/316L/440C stainless — food, pharma, marine, clean-room. Al 6061/7075 hard-anodized — lightweight. Bronze ZA — sliding sleeve bushings. Ti Grade 5 — aerospace/medical.

Standard ground OD / bore: Ra 0.4 µm. Precision bearing seats: Ra 0.2 µm. Honed bore: Ra 0.2 µm, roundness ≤ 0.002 mm. Mirror finish for seals: Ra 0.1 µm. All measured by contact profilometer and reported on the inspection certificate.

Yes — HXC machines precision sleeves with integral keyways (in bore and/or OD), set-screw tapped holes, locking-nut threads, and flanges in one 5-axis setup. Keyway position and depth are held to DIN 6885. All features maintain concentricity to the ground bore/OD surfaces within the tolerance of the part.

Yes — HXC machines tapered adapter sleeves (per the bearing standard 1:12 or 1:30 taper bore) used to mount self-aligning ball bearings and spherical roller bearings onto plain cylindrical shafts. The taper bore is ground and lapped to the bearing maker's contact pattern requirement, and the OD is ground concentric to the taper bore.