Release time : 2015-06-10 11:34:01
By Bearing Manufacturer>Bearing News>A Brief Introduction of How Ball Bearing Manufacturers Make ball Bearings
This article will describe only how ball bearings manufacturers make ball bearings. In these bearings, the rolling part is a ball, which rolls between inner and outer rings called races. The balls are held by a cage, which keeps them evenly spaced around the races. In addition to these parts, there are a lot of optional parts for special bearings, like seals to keep oil or grease in and dirt out, or screws to hold a bearing in place. We won't worry here about these fancy extras.
Almost all parts of all ball bearings are made of steel. Since the bearing has to stand up to a lot of stress, it needs to be made of very strong steel. The standard industry classification for the steel in these bearings is 52100, which means that it has one percent chromium and one percent carbon (called alloys when added to the basic steel). This steel can be made very hard and tough by heat treating. Where rusting might be a problem, bearings are made from 440C stainless steel.
The cage for the balls is traditionally made of thin steel, but some bearings now use molded plastic cages, because they cost less to make and cause less friction.
Till that all of the parts are manufactured by ball bearing manufacturers, the bearing needs to be put together. First, the inner race is put inside the outer race, only off to one side as far as possible. This makes a space between them on the opposite side large enough to insert balls between them. The required number of balls is put in, then the races are moved so that they are both centered, and the balls distributed evenly around the bearing. At this point, the cage is installed to hold the balls apart from each other. Plastic cages are usually just snapped in, while steel cages usually have to be put in and riveted together. Now that the bearing is assembled, it is coated with a rust preventative which would perform as Stainless Steel Bearings which have the characteristic of corrosion resistance and packaged for shipping.
Ball bearing manufacturers treat bearing making as a very precise business. Tests are run on samples of the steel coming to the factory to make sure that it has the right amounts of the alloy metals in it. Hardness and toughness tests are also done at several stages of the heat treating process. There are also many inspections along the way to make sure that sizes and shapes are correct. The surface of the balls and where they roll on the races must be exceptionally smooth. The balls can't be out of round more than 25 millionths of an inch, even for an inexpensive bearing. High Speed or precision Bearings are allowed only five-millionths of an inch.