What is Bearing?
Bearings are machine components that allow components to move relative to one another. Bearings are classified into two types: contact and non-contact. Contact-type bearings, which include sliding, rolling, and flexural bearings, make mechanical contact with the equipment.
Non-contact bearings include liquid, air, mixed-phase, and magnetic bearings. Static friction is eliminated because there is no mechanical contact.
A bearing is a machine component that restricts relative motion to only the desired motion while reducing friction between moving parts.
For example, the bearing’s design may allow for free linear movement of the moving part or free rotation around a fixed axis; or it may prevent a motion by controlling the vectors of normal forces bearing on the moving parts.
Most bearings make the desired motion easier by reducing friction. Bearings are classified broadly based on the type of operation, the motions permitted, or the loads (forces) applied to the parts.
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Functions of Bearing
Bearings reduce friction by providing smooth metal balls or rollers and a smooth inner and outer metal surface against which the balls roll. The load is “bear” by these balls or rollers, allowing the device to spin smoothly.
Many of the machines we use every day are made possible by bearings. If we didn’t have bearings, we would have to replace parts that wear out due to friction. Objects roll faster than they slide. Your car’s wheels are analogous to large bearings. If you had skis instead of wheels, your car would be much more difficult to push down the road.
Bearings are typically subjected to two types of loading: radial and thrust. The bearing may experience radial loading, thrust loading, or a combination of the two depending on where it is used.
An electric motor and pulley combination’s bearings face only a radial load. The tension in the belt connecting the pulleys accounts for most of the load.
Bar stool and lazy Susan bearings are completely thrust-loaded. The weight of the objects accounts for the entire load.
Types of Bearing
Rolling Elements Bearings
Rolling element bearings have rolling elements shaped like balls or cylinders. We know that rolling a wheel is easier than sliding it on the ground because rolling friction’s magnitude is lower than sliding friction’s. The same logic is at work here. Rolling element bearings allow parts to move freely in rotational motion.
Even when linear motion is required in applications, converting rotational motion to sliding motion is simple. Think about an escalator or a conveyor. Even though the motion is linear, it is powered by rollers powered by motors.
Ball bearings are one of the most widely used bearing classes. It comprises a row of balls that act as rolling elements. They are trapped between two metal annulus-shaped pieces. These metal pieces are referred to as races. The inner race is free to rotate, whereas the outer race is fixed.
Ball bearings have very low rolling friction but have a limited load-carrying capacity. This is due to the small contact area between the balls and the races. Aside from radial loads, they can support axial loads in both directions.
Deep Groove Ball Bearings
This is the most common type of ball bearing. A ring of balls trapped between the two races transmits the load and allows rotational motion between the two races. A retainer holds the balls in place.
They have very low rolling friction and are designed to be quiet and vibration-free. As a result, they are ideal for high-speed applications.
Angular Contact Ball Bearings
The inner and outer races of this ball bearing are displaced from each other along the bearing axis. This type is intended to withstand greater axial loads in both directions and radial loads.
The axial load can be transferred through the bearing to the housing due to the inner and outer races shift. This bearing is appropriate for applications requiring rigid axial guidance.
Self-Aligning Ball Bearings
This ball bearing type is resistant to shaft-to-housing misalignment caused by shaft deflection or mounting errors.
Like deep groove ball bearings, the inner ring is followed by two rows of balls and the outer ring. The outer ring is concave, which allows the inner ring to rearrange itself depending on the misalignment.
Thrust Ball Bearings
Thrust ball bearings are a type of ball bearing that is specifically designed for axial loads. They are incapable of withstanding radial loads.
Thrust ball bearings operate quietly and smoothly and can handle high-speed applications.
Bearings on Rollers
As load-carrying elements between the races, roller bearings use cylindrical rolling elements rather than balls. A roller is an element whose length is greater than its diameter (even if only slightly). They can withstand higher loads because they are in line contact with the inner and outer races (rather than point contact as with ball bearings).
Cylindrical Roller Bearings
These are the most basic of roller bearings. These bearings can withstand heavy radial loading and high speeds. They also have high stiffness, good axial load transmission, low friction, and long service life.
The load capacity can be increased even further by removing the cages or retainers typically used to hold the cylindrical rollers in place. This allows for the addition of more rollers to carry the load.
Applications of Bearing
- Aviation Cargo System
- Actuators for Aerospace Wings
- Card Readers and ATMs
- Blenders for commercial use.
- Dental Hand Instruments
- Motors powered by electricity
Benefits of Bearings
- Friction resistance and power consumption are low, mechanical efficiency is high, and it is simple to start.
- Size standardization, interchangeability, ease of installation and disassembly, and repairability
- The structure is more compact, the weight is lighter, and the axial size is smaller.
- High precision, high load capacity, and long service life.
- Some bearings are capable of automatic heart adjustment.
- It is suitable for mass production, has stable and reliable quality, and has a high production efficiency.
- Because the transmission’s friction torque is much lower than the fluid dynamic pressure bearing, the friction temperature rises, and the power consumption is low.
- The axial size is smaller than that of a conventional fluid dynamic bearing.
- Radial and thrust loads can be carried simultaneously.
- The unique bearing design can achieve excellent performance over a wide load-velocity range.