The Manufacture of Ball Bearings

Ball bearings are at the heart of almost every product with a rotating shaft. We’ve come to rely heavily on these products--and in turn on the bearings too--for the benefits they provide. We expect these products (and the bearings within) to give us uninterrupted, dependable "lifetime" service. This expectation has been built, in part, due to the increasingly reliable performance of precision components such as bearings. The highly precise surface finish, material properties, cleanliness, dimensions and tolerances of today’s bearings contribute significantly to product performance.

Although most bearing specifications and manufacturing tolerances are quantified in one-ten thousandths of an inch (1/10,000) by ABMA, NTN actually measures the production process in micron and submicron ranges. It is this precise measuring capability that gives NTN the ability to produce a product with less variation from piece to piece, lot to lot, and day to day. NTN’s efforts have led to recognition as a world leader in Statistical Process Control (SPC). Every manufacturing process is 100% checked and feedback provided to ensure the integrity of the process and product.

Note: A micron (an abbreviation for micrometers) is one-millionth of a meter, or, 25,400 microns equals one (1) inch.

Grinding the Outer Diameter

Finish Grinding of the Ring Faces

Inner/Outer Ring Manufacturing Process

• The bearing steel is machined (turned) or forged into rough cut, basic ring configurations;
• Rings are machined to within rough tolerance specifications;
• Rings are heat treated to increase the steel’s strength;
• Ring faces receive the final grinding, removing any rough spots;
• The ring O.D. and I.D. are finish ground to a smooth surface;
• Raceways are also finish ground to an even surface;
• The raceways are honed to a polished finish; and,
• The rings are then cleaned and readied for assembly.

Bearing Steel Wire Cold Stamped

• The bearing steel wire is cold stamped (headed) into roughly shaped balls;
• Balls are rough ground to remove the flashing (orbit) created during heading;
• The balls are heat treated for strength;
• Balls are rough ground again to remove coarser imperfections;
• The balls are next finish ground;
• The balls are lapped (a fine-polishing process); and,
• Finally, the balls are cleaned and readied for assembly.

Retainers Finish Formed

• Blanks, or donut shaped discs, are stamped out of strip steel;
• The retainers are partially (rough) formed;
• The retainers are next finish formed;
• Retainers are then punched (if rivets are to be used);
• Retainers go through a deburring process; and,
• The finished retainers are cleaned and readied for assembly.

Bearing Assembled & Treated with Rust Preventative

The bearing components will next go through the final assembly process. The assembled bearing is then cleaned, lubricated, noise tested, etc.; it’s ready to meet your expectations!