Ever since man began to need to move things, he has used round rollers to make the job easier. Probably the first rollers were sticks or logs, which were a big improvement over dragging things across the ground, but still pretty hard work. Egyptians used logs to roll their huge blocks of stone for the pyramids. Eventually, someone came up with the idea of securing the roller to whatever was being moved, and built the first "vehicle" with "wheels." However, these still had bearings made from materials rubbing on each other instead of rolling on each other. It wasn't until the late eighteenth century that the basic design for bearings was developed. In 1794, Welsh ironmaster Philip Vaughan patented a design for ball bearings to support the axle of a carriage. Development continued in the nineteenth and early twentieth centuries, spurred by the advancement of the bicycle and the automobile.
There are thousands of sizes, shapes, and kinds of rolling bearings; ball bearings, roller bearings, needle bearings, and tapered roller bearings are the major kinds. Sizes run from small enough to run miniature motors to huge bearings used to support rotating parts in hydroelectric power plants; these large bearings can be ten feet (3.04 meters) in diameter and require a crane to install. The most common sizes can easily be held in one hand and are used in things like electric motors.
This article will describe only 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.
Raw Materials
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.
The Manufacturing
Process
There are four major parts to a standard ball bearing: the outer race, the rolling balls, the inner race, and the cage.
Races
1 Both races are made in almost the same way. Since they are both rings of steel, the process starts with steel tubing of an appropriate size. Automatic machines similar to lathes use cutting tools to cut the basic shape of the race, leaving all of the dimensions slightly too large. The reason for leaving them too large is that the races must be heat treated before being finished, and the steel
Surprisingly, the rolling balls start out as thick steel wire. Then, in a cold heading process, the wire is cut into small pieces smashed between two steel dies. The result is a ball that looks like the planet Saturn, with a ring around its middle called "flash."
Surprisingly, the rolling balls start out as thick steel wire. Then, in a cold heading process, the wire is cut into small pieces smashed between two steel dies. The result is a ball that looks like the planet Saturn, with a ring around its middle called "flash."
usually warps during this process. They can be machined back to their finished size after heat treating.
2 The rough cut races are put into a heat treating furnace at about 1,550 degrees Fahrenheit (843 degrees Celsius) for up to several hours (depending on the size of the parts), then dipped into an oil bath to cool them and make them very hard. This hardening also makes them brittle, so the next step is to temper them. This is done by heating them in a second oven to about 300 degrees Fahrenheit (148.8 degrees Celsius), and then letting them cool in air. This whole heat treatment process makes parts which are both hard and tough.
3 After the heat treatment process, the races are ready for finishing. However, the races are now too hard to cut with cutting tools, so the rest of the work must be done with grinding wheels. These are a lot like what you would find in any shop for sharpening drill bits and tools, except that several different kinds and shapes are needed to finish the races. Almost every place on the race is finished by grinding, which leaves a very smooth, accurate surface. The surfaces where the bearing fits into the machine must be very round, and the sides must be flat. The surface that the balls roll on is ground first, and then lapped. This means that a very fine abrasive slurry is used to polish the races for several hours to get almost a mirror finish. At this point, the races are finished, and ready to be put together with the balls.
Contact Us
ARB Bearings Limited
H-22, Udyog Nagar
New Delhi - 110041, Delhi, India
Phone: +(91)-(11)-25471274 / 25471255 / 25186300
Fax: +(91)-(11)-25475455 / 25470126
Email: info@arb-bearings.com, export@arb-bearings.com,
sales@arb-bearings.com
Website :http://arb-bearings.com
For Export Enquiry :
Mr. Divay Rathee : +91-9968373086
This article will describe only 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.
Raw Materials
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.
The Manufacturing
Process
There are four major parts to a standard ball bearing: the outer race, the rolling balls, the inner race, and the cage.
Races
1 Both races are made in almost the same way. Since they are both rings of steel, the process starts with steel tubing of an appropriate size. Automatic machines similar to lathes use cutting tools to cut the basic shape of the race, leaving all of the dimensions slightly too large. The reason for leaving them too large is that the races must be heat treated before being finished, and the steel
Surprisingly, the rolling balls start out as thick steel wire. Then, in a cold heading process, the wire is cut into small pieces smashed between two steel dies. The result is a ball that looks like the planet Saturn, with a ring around its middle called "flash."
Surprisingly, the rolling balls start out as thick steel wire. Then, in a cold heading process, the wire is cut into small pieces smashed between two steel dies. The result is a ball that looks like the planet Saturn, with a ring around its middle called "flash."
usually warps during this process. They can be machined back to their finished size after heat treating.
2 The rough cut races are put into a heat treating furnace at about 1,550 degrees Fahrenheit (843 degrees Celsius) for up to several hours (depending on the size of the parts), then dipped into an oil bath to cool them and make them very hard. This hardening also makes them brittle, so the next step is to temper them. This is done by heating them in a second oven to about 300 degrees Fahrenheit (148.8 degrees Celsius), and then letting them cool in air. This whole heat treatment process makes parts which are both hard and tough.
3 After the heat treatment process, the races are ready for finishing. However, the races are now too hard to cut with cutting tools, so the rest of the work must be done with grinding wheels. These are a lot like what you would find in any shop for sharpening drill bits and tools, except that several different kinds and shapes are needed to finish the races. Almost every place on the race is finished by grinding, which leaves a very smooth, accurate surface. The surfaces where the bearing fits into the machine must be very round, and the sides must be flat. The surface that the balls roll on is ground first, and then lapped. This means that a very fine abrasive slurry is used to polish the races for several hours to get almost a mirror finish. At this point, the races are finished, and ready to be put together with the balls.
Contact Us
ARB Bearings Limited
H-22, Udyog Nagar
New Delhi - 110041, Delhi, India
Phone: +(91)-(11)-25471274 / 25471255 / 25186300
Fax: +(91)-(11)-25475455 / 25470126
Email: info@arb-bearings.com, export@arb-bearings.com,
sales@arb-bearings.com
Website :http://arb-bearings.com
For Export Enquiry :
Mr. Divay Rathee : +91-9968373086
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