How are ball bearings made?

Question

They seem perfectly spherical, no ring around the middle from casting. no nipples They are uniform , precise size and they are mass produced. How do they change a lump of steel into an exact ball with no visible markings and do it in large numbers

Answer 1

High speed, cold heading machines take a wire or rod feed, chop it to length and cold forge a ball to fairly close limits of size and sphericity. Basically this is done by taking a cut slug of the right volume and "bonking" it between two hemispherical dies.

Heat treatment follows..in continuous conveyor fed furnaces.

Then the balls are fed in a continuous stream to a series of grinding and lapping machines. These look like the old flour grinding mills..two discs contra-rotating (or rotating at differential speeds) the balls feed in the center and sphericity is 'Generated" just as you would form a ball of play-do by rolling it between your hands.

Gauging is automatic..usually by rolling the balls along two, slightly divergent hardened knife edges..amazing accuracy!

Balls are graded for size and sent off to be assembled with similarly graded inner and outer rings on a "Selective Assembly" basis. This may be done in the building next door..or one half way around the world!! Bearings are a Multinational concern!

The assembly plants run, 24/7/365 fully automated, on an almost "lights out" basis. Noisy places they are..Busy but no one about unless something needs fixing.

A modern ball bearing can go through every stage of manufacture, assembly, packaging, shipping and assembly (For instance into an automobile) without being touched by human hand or seen by human eye.

Answer 2

How Are Ball Bearings Made

Answer 3

Surprisingly, ball bearings start out as thick wire. This wire is fed from a roll into a machine that cuts off a short piece, and then smashes both ends in toward the middle. The balls now look like the planet Saturn, with a ring around the middle called a "flash." The bulge around the middle of the rolling balls is removed in a machining proess. The balls are placed in rough grooves between two cast iron discs. One disc rotates while the other one is stationary. The stationary wheel has holes through it so that the balls can be fed into and taken out of the grooves. A special conveyor feeds balls into one hole, the balls rattle around the groove, and then come out the other hole. They are then fed back into the conveyor for many trips through the wheel grooves, until they have been cut down to being fairly round, almost to the proper size, and the flash is completely gone. The balls are left oversize so that they can be ground to their finished size after heat treatment. The amount of steel left for finishing is not much; only about 8/1000 of an inch, which is about as thick as two sheets of paper.

From here, the balls are heat treated, ground, and lapped, which leaves the balls with a very smooth finish. The balls become hard and tough after heat treating and tempering. After heat treatment, the balls are put back into a machine that works the same way as the flash remover, except that the wheels are grinding wheels instead of cutting wheels. These wheels grind the balls down so that they are round and within a few ten thousandths of an inch of their finished size.

The end result is steel ball bearing that is extremely smooth.


Bearing making is a very precise business. High-speed or precision bearings are allowed only five-millionths of an inch error.

Ball bearings will be used for many years to come, because they are very simple and have become very inexpensive to manufacture. Some companies experimented with making balls in space on the space shuttle. In space, molten blobs of steel can be spit out into the air, and the zero gravity lets them float in the air. The blobs automatically make perfect spheres while they cool and harden. However, space travel is still expensive, so a lot of polishing can be done on the ground for the cost of one "space ball".

Answer 4

The first step is a cylinder of steel is double upset forged into a sphere, with a ring at the parting line (it looks like saturn). the nest step is that this ring is shorn off by rolling the ball in a set of counter rotating circular cast iron plates with spiral grooves cut in them. The last step is finish grinding, with a grind stone on top and a cast iron lpa plate on the bottom; again, both the grind stone and the lap plate have hemispherical grooves cut in them that spiral inward to a hole where the balls drop out.

It's a pretty amazing process. It's one of the most underrated inventions of all time. People have absolutely no idea that modern automobiles and machines are impossible without this ingenius yet humble and relatively unknown invention.

Answer 5

i think it is made by atomization that is steel is heated until it is melted then it is spraied in special size and then it is grinding or rubbing.

Answer 6

cuase thats how they roll, lol.

just kidding. no Im sure they are made.. no wait.. i just lost it.. I may be back later to answer that.

Answer 7

how it's made ;)