How ball bearings are made

Date Added: January 03, 2012 01:10:08 PM

Author: Polina

Steel ball bearings comprise of three main type of component: the inner and outer raceways, the balls themselves and the ball cage. Bearing races are normally produced by centerless grinding, a manufacturing process whereby theworkpiece is ground without the use of a spindle, and is instead rested on a pedestal between a high pressure grinding wheel and a stationary guiding wheel. This method has a very large throughput as changing the workpiece is a quick process and easy to automate, enabling its operational costs to be recovered promptly. It can also produce results of very high quality and with small error margins when deployed in several stages utilizing grinding wheels of increasingly fine abrasive quality: Typically, this will include a rough grind which will achieve the correct diameter and roundness, and a final grind to achieve the precision dimensions demanded by applications requiring specialist bearings. The internal tracks of the raceways are also machine polished in order to minimise friction. Every stage of the raceway grinding and polishing process includes automated quality control, as customers generally have very tight size allowances in their ball bearing specifications. This is of course particularly important for bespoke applications requiring very small bearings. Balls are produced from a length of steel wire of the correct diameter, cut by machine and then punched by a die into a roughly spherical shape. These are then ground and polished in a similar way to the raceways in order to achieve the high grades of precision required for most applications. Machinery with a high throughput is of course vital, as is the accuracy of the tooling. There are also some chemical processes which can be employed after grinding to achieve a higher grade of precision. A bearing cage is used to hold the rolling elements in place inside the raceway, preventing them from bunching up and increasing the friction between elements, and allowing for a more even distribution of lubricant within the bearing. These are typically manufactured from a high tensile strength to weight ratio material such as steel or cast from a high performance plastic which will be able to tolerate the rapid accelerations that the bearings will likely encounter. Additionally, the manufacturing material must, like all other components of the bearing, be resistant to chemicals such as petrol and grease, and must have a low absorption of water and lubricant. The bearing is thoroughly washed with kerosene before being injected with an elastohydrodynamiclubricant with the correct minimum dynamic viscosity for the diameter and application of the bearing. A plastic or rubber seal is then applied to finish the bearing and prevent leakage of the lubricant. For more information visit Acorn Industrial Services

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