Bearing-Mount
Shafts

A bearing-mount shaft is a shaft specifically dimensioned for the correct interference or clearance fit with rolling element bearings. The bearing inner race must be pressed onto the shaft with a controlled interference (k5 or m5 tolerance for rotating inner race) to prevent the race from spinning (fretting) — or with a controlled clearance (f6/g6 for non-rotating inner race) to allow thermal expansion or axial sliding. An incorrect fit causes premature bearing failure.

The fit depends on whether the inner race rotates relative to the load direction: Rotating inner race (most common — shaft rotates in fixed housing): k5 or m5 — slight interference. Non-rotating inner race (shaft stationary, outer race rotates): f6 or g6 — slight clearance. The exact tolerance depends on bearing bore diameter and radial load. HXC engineers confirm the correct fit class from your bearing designation and load conditions.

Too loose (excess clearance): the bearing inner race micro-slides (fretting) on the shaft at every load cycle — producing iron oxide debris, pitting the shaft, and causing vibration. Too tight (excess interference): excessive hoop stress on the bearing inner race reduces the radial internal clearance below the minimum, causing ball contact angles to increase and dramatically shortening bearing fatigue life. Both failures are common when correct fit tolerances are not maintained.

Yes — HXC grinds bearing seats to any standard tolerance class: IT4 (gauge quality), IT5 (k5, m5, h5, f5), IT6 (k6, m6, h6, f6, g6), IT7 (H7 for housings). All are ground in the same 5-axis setup as the rest of the shaft, ensuring concentricity between all bearing seats within 0.005 mm TIR. Full CMM measurement of every bearing seat is standard.

Prototype (1–5 pcs, turned + ground): 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) for industrial and automotive. 20CrMnTi (carburized) for maximum surface fatigue. SUS303 / 316L stainless for food, pharma, marine. Al 6061 / 7075 hard-anodized for lightweight. Ti Grade 5 for aerospace / medical. PEEK / POM for sterilizable or self-lubricating applications.

Standard ground OD: Ra 0.4 µm. Precision bearing seats: Ra 0.2 µm. Mirror finish for seals: Ra 0.1 µm. All measured by contact profilometer and reported on the inspection certificate.

Yes — keyways, splines, threads, cross-holes, flats, and tapers are all machined in the same 5-axis turning-milling setup, ensuring concentricity between all features within 0.003 mm TIR.