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Pearson Scott Foresman (Wikimedia Commons) · Public domain

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Emma

11. 10월 2026

Ball Bearings: Races, Balls and Cage

A ball bearing has four parts: an outer race, an inner race, the balls that roll between them, and a cage that keeps the balls evenly spaced. Almost all of it is steel, usually 52100 (1% chromium, 1% carbon), which can be made very hard and tough by heat treating; 440C stainless is used where rust is a problem. The races are turned from tubing, the balls are cold headed from thick wire, both are hardened, tempered, ground and lapped to an almost mirror finish, and the cage is stamped from thin sheet. Even an inexpensive bearing's balls may be out of round by no more than 25 millionths of an inch; precision bearings allow five millionths.

고급

Factory process

안내

Turn the races

Cut the basic shape of both races from steel tubing on automatic lathe-like machines, leaving every dimension slightly oversize: the steel usually warps in heat treatment.

이 단계의 재료:

베어링강 관(52100)1 as required

필요한 도구:

자동 선반

Harden and temper the races

Heat to about 843 °C (1,550 °F) for up to several hours depending on size, then quench in oil: hard but brittle. Temper at about 149 °C (300 °F) and let cool in air: hard and tough.

필요한 도구:

유랭 연속 담금질로

뜨임로

Grind and lap the races

The hardened steel is too hard to cut, so grind almost every surface: the fitting surfaces round, the sides flat. Grind the ball track, then lap it for several hours with a very fine abrasive slurry to an almost mirror finish.

이 단계의 재료:

래핑 컴파운드1 as required

필요한 도구:

베어링 궤도륜 연삭기

궤도 래핑기

Cold head the balls

Feed thick wire from a roll into a machine that cuts off a short piece and smashes both ends in toward the middle between two dies, without heating. The ball comes out with a ring of "flash" round its middle.

이 단계의 재료:

베어링강 선재(52100)1 as required

필요한 도구:

냉간 압조기

Remove the flash

Run the balls many times round rough grooves between two cast-iron discs, one turning and one fixed, until the flash is gone and they are nearly round. Leave about 0.008 in (0.2 mm) for finishing.

필요한 도구:

볼 버 제거기

Harden, grind and lap the balls

Heat treat and temper the balls like the races. Grind them in the same kind of disc machine with grinding wheels to within a few ten-thousandths of an inch, then lap them 8–10 hours on cast-iron wheels with lapping compound.

이 단계의 재료:

래핑 컴파운드1 as required

필요한 도구:

유랭 연속 담금질로

뜨임로

볼 연삭기

볼 래핑기

Stamp the cage

Stamp the cage halves from thin steel sheet and bend them to shape in a die. (Plastic cages are injection moulded instead.)

이 단계의 재료:

강판1 as required

필요한 도구:

스탬핑 프레스

Assemble

Put the inner race inside the outer race, pushed as far to one side as it goes, and drop the balls into the gap opposite. Centre the races and spread the balls evenly, fit the cage (steel cages riveted, plastic ones snapped in) and coat the bearing with rust preventive.

이 단계의 재료: