Ball Bearings

What is a ball bearing?

What is a ball bearing? Generally speaking ball bearings are made up of inner ring, outer ring, ball and cage, for the inner ring acts to engage the shaft and rotate with the shaft. The outer ring of the ball bearing is matched with the bearing seat to play a supporting role. The frictional resistance is small, the power consumption is small, and the mechanical efficiency is high. These are the characteristics of the ball bearing, and the size for ball bearing is also very standardized, interchangeable, and easy to install and disassemble. For advantage of stable quality, high precision, high speed, little wear and long service life, so the ball bearings are also widely used in various machinery. Lily bearings is the leader of the bearing suppliers.

Ball bearings are also used in a wide range of applications, not only to withstand radial loads but also with two-way axial loads. It is very suitable for many high speed and low noise, low vibration requirements. When the ball bearing is subjected to a pure radial load, the contact angle is zero. When the ball bearing has a large radial clearance, it has the performance of angular contact, generally the friction coefficient is relatively small, and the extreme speed of the bearing is also high, especially in the case of a large high-speed operation, the ball bearing is even more excellent.

For the extreme speed operation, the ball bearings are extremely durable and needn't frequent maintenance. The bearing has a simple structure, very high extreme rotation speed, and many changes in the size and form of the ball bearing, so it has a wide range of applications in the general machinery industry such as precision instruments, low noise motors, and automobiles.

Let’s recap about ball bearings.

What are the parts in a ball bearing setup?

Ball bearings consist of four main components: inner ring, outer ring, balls, and cage.

How does ball bearing work?

Think of ball bearings as small wheels that work inside the machine. When pulling a cart, you would want to pull the cart with wheels on the ground, and would never drag the cart without any wheel. That’s the basic principle behind any ball bearing.

In a typical ball bearing setup, the inner ring fits on a shaft where the rotation happens. The outer ring fits tightly inside the outer structure (such as a motor casing) which must be stationary.

The balls are parts that fill the gap between the inner and outer rings. The balls provide "point contact" that allows relative motion between the outer and inner rings.

The cage is normally a metal or ceramic structure that holds all the balls fixed at that relative positions but allows them to freely rotate.

When the shaft rotates, the balls start spinning inside the cage along with the rotating inner ring. A relative movement between the inner and outer rings is established with minimal contact area.

What problems can ball bearings solve?

In many industrial equipment, relative movement has to happen between different components. The relative movement involves contact between two components which creates friction.

Having friction between components when they are moving in high speed is never ideal. A solution to reduce the friction as much as possible must be applied. The solution is to reduce the contact area between the two moving components through the use of ball bearings.

Ball bearings enable "point contact" between the inner and outer rings when they are moving at high speed. Because the contact becomes minimal after using ball bearings, the friction is much lower.

In which industries are ball bearings mostly used?

Ball bearings are widely used in industries such as automotive, aerospace, paper making, toy making, and home appliances.

Pay attention to details and precision

When using ball bearings, do pay attention to the following. It is important to know that there are tolerances between the shaft (where the inner ring is attached), and the outer ring. Ball bearings are components that required “precision”. Therefore, when there is error in installation, maintenance becomes difficult and the bearings would cause failures for the mechanical operations.

How are the “balls” of the ball bearings made?

Stage one of the process involves a cold or hot forming operation in which a wire of metal more or less the diameter of the finished ball is fed through a heading machine. This machine has a metal cavity just like the shape of a hemisphere on each side. The job of the machine is to slam shut on the wire forcing the metal into the shape of a ball. The balls that come out of this machine have a ring of metal around them which make the balls look like planet Saturn.

The ring of metal is removed in the next machine. This second machine rolls the ball between the rill plates which are two very heavy hardened steel plates. One rill plate is stationary and the other spins. Together the rill plates guide the balls around in a circular path. One of the rill plates has a section cut out of it that allows the balls to enter and exit the grooves. The machine is filled with balls when it is turned on and running. When the balls travel through the grooves, they spin and tumble. Any rough edges on the balls would get cut off, and the balls would become spherical shape. In this process, the balls are highly compressed, and they would end up having a very hard surface. During this process, the metal balls generate a lot of heat. Water is poured over the balls and plates to cool them down. The balls would fall into an open section before they enter a different groove. After the balls travel through many different grooves, they will come out all having the same shape.

The sizes of the final balls can be controlled by some variables. The variables are the speed of the spinning plates and the duration of the balls that are left in the machine. Changing the variables would produce balls of different sizes.

The balls now have to go through the grinding operation. This operation is to ensure the size of all the balls is perfect. The machine has a coolant with an abrasive. The balls would travel through this machine and come out with their final dimensions.

Finally, the balls would go through the lapping operation. This time, the machine uses a softer metal and a polishing paste with much less pressure when squeezing the plates. The balls that come out of this last machine would have smooth and shinny surface.

What are the main types of bearing?

There are two main types. The first type is hydrodynamic where no pump is used at all.

The second type is hydrostatic. An external pump must be used to pump up the oil for the oil to properly work between the journal and bearing.

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