Different Kinds of Bearings: Categories And Choosing Tips

Different kinds of bearings

The bearing is one of the leading components in various machinery and serves numerous industries, from automotive to oil & gas, and manufacturing to aerospace. Over time, the list of different kinds of bearings has grown, and can now be broadly classified as plain, ball, roller, and special-purpose bearings. 

Each of these categories has a long list of different versions, each engineered for specific circumstances. A large variety of products usually presents choosing challenges for many resellers, dealers, and end-users.

Buying with the focus on important points such as speed, working conditions, loading requirements, and misalignment considerations can help enhance the success of CNC machining projects. All these points and others have been covered in this coverage of different kinds of bearings.

Read on for more insights. 

 

What Is A Bearing?

A bearing in a setup

A bearing is a mechanical component incorporated in mechanical systems to perform different functions, but mainly to smooth and simplify movement or rotation. It does so through force and motion transfer, either directly (contact bearing) or indirectly (non-contact bearing) with the source of the force or motion. 

The fundamental bearing components are; 

• Inner ring & raceway
• Outer ring & raceway
• Rolling elements 
• Cage 

Parts of a bearing

The inner ring is the smaller one and rests on the shaft. For ball bearings, this ring has a raceway is a groove, while for roller bearings, it is flat. The same raceway design is on the outer ring, but facing the center of the bearing. 

Bearings rotate smoothly due to the presence of balls or rollers that move between the outer and inner rings. These bearing components are better known as rolling elements. 

Since these parts take care of the bulk of the friction, they must be expertly designed and manufactured. The surface quality and symmetry of rolling elements must be perfect to enhance performance and minimize heat and noise generation. 

When the cage is added to the set, a complete bearing is formed. Its main function is to ensure the rolling elements remain in their places. 

 

What Is the Function Of a Bearing?

Bearings are instrumental in the smooth, efficient, and safe running of machinery, enhancing mechanical efficiency and controlling motion. While the core function and what most people relate to is friction reduction, these mechanical components are useful in more ways. 

They support loads, distribute loads, and dissipate heat for safe machinery operation. 

Supporting And Distributing Loads

Bearings are typically fixed on Crankshaft setups and other shafts to support loads, for instance, in a car motor shaft. As the bearing supports the load, the shaft can rotate smoothly. 

Types of loads on a bearing

Reducing Friction 

This is the most recognizable function of the bearing. Wherever bearings are used, whether in the valve train of the car engine valves, the landing gear of an aircraft, a car wheel, or robotic arms in a medical facility, they replace sliding motion with rolling motion. 

This effectively reduces friction between the moving parts. In other words, the bearings we will list here provide improved rotary or linear motion on a fixed axis. 

Minimizing Wear And Tear

Bearings, by supporting weight and movement, can significantly reduce wear and tear of moving parts. The bearings provide a smooth surface for the opposing forces to interact. Apart from enhancing the durability of these parts, this also minimizes maintenance costs.

Categorization Of Different Kinds Of Bearings

Bearings will most likely fall under plain bearings, ball bearings, roller bearings, mounted bearings, and special-purpose bearings classes. A helpful way to analyze the different kinds of bearings is to categorize these mechanical components broadly based on their design and function. Whichever industry you focus on. 

The motion properties, applications, and ideal load type for each of these types of bearings are distinct, so an exploration of their characteristics is worthwhile. 

Type of Bearing 1: Plain Bearing

The plain bearing is the most basic and popular type, renowned for its simplicity and versatility. The mechanism is simple: The surfaces slide against each other with the help of lubrication. 

Plain bearing

Unlike other options like roller bearings and ball bearings, plain bearings don’t have moving parts. They have a press-fit design instead, with the bearing and moving part in direct contact. Their maintenance-free nature is suitable for applications where durability and low-cost operation are prioritized, for instance, in Camshafts. 

There are several types of plain bearings, including sleeve bearings and flange bearings. 

Type of Bearing 2: Ball Bearing

Ball bearings, part of rolling element bearings, are characterized by spherical rolling components, which enable the mechanical device to effectively handle axial and radial loads. This class comprises designs such as angular contact ball bearings, deep groove ball bearings, self-aligning ball bearings, and thrust ball bearings.

Angular Contact Ball Bearings

Angular contact ball bearings are designed to handle a case where there are significant axial loads. The tracks of these bearings are tilted towards the axial direction, creating an inclined contact angle between the ball and tracks. 

Angular contact ball bearings

Deep Groove Ball Bearings 

These ball bearings feature outer and inner rings with deep grooves that enable the balls to support both axial and radial loads. These types of bearings are common in high-speed applications, for instance, car starters, high-precision CNC spindles, and rotary saws. 

Self-Aligning Ball Bearings

This type of ball bearing is designed to minimize friction and support loads in three-degree misaligned shafts. Whether this misalignment is dynamic or axial, these bearings are still applicable. 

With their self-adjusting capability, these bearings are useful in loaders, generators, pumps, and such machinery. 

Thrust Ball Bearings

The distinctive thrust bearing application is to support axial load on a shaft, preventing axial thrust of the shaft. These bearings are not ideal for supporting radial loads because they are solely designed for axial loads.

Thrust ball bearing

You can find these components in machine tool spindles, automotive clutches, and steering gears, among other applications. 

Type of Bearing 3: Roller Bearing

For roller bearings types, the most distinctive parts are the cylindrical rollers, which are designed to carry incredible loads. Under this category of rolling element bearings, we have options like cylindrical roller bearings, needle roller bearings, spherical roller bearings, and tapered roller bearings. 

Cylindrical Roller Bearings 

Cylindrical roller bearings types comprise cylindrical-shaped rollers within the raceways. Their linear contact with the rings enhances load distribution over a large area. These bearings are common in applications of significant radial loads, for instance, car transmission shafts and electric motors. 

Needle Roller Bearings Types

Needle roller bearing

This type contains thin, long bearings arranged in the casing. The ends of these bearings may taper or be hemispherical. The design is excellent at overcoming high radial loads in two-stroke engines, thread feeders in textile machinery, and servo motors for industrial robots, among others. 

Spherical Roller Bearings

These are the perfect bearings for significant radial loads and some axial ones. They come with spherical rollers built to accommodate angular misalignment. You will find these kinds of bearings in wind turbine shafts, mining machinery, and rolling mills. 

Tapered Roller Bearings

As can be deduced from the name, these roller bearings types feature tapered rollers whose rotating axes converge. Popular in automotive applications, these bearings handle both radial and axial loads. 

Tapered roller bearing

Type of Bearing 4: Special Purpose Bearing

The first two categories of bearings already discussed are considered standard and, thus, are the most common in applications related to CNC machining services. However, there are instances where these mechanical components may be inadequate – very tight dimensional limits, extreme working conditions, unique load requirements, etc. 

Special-purpose bearings come in such cases. They are available in three main types, namely air bearings, linear bearings, and magnetic bearings.

Air Bearings 

Air bearing

The bearings can also be called aerodynamic or aerostatic bearings because their design is based on the concept of a thin film of air supporting the load instead of the standard direct contact between CNC parts. 

These components are renowned for low vibration and excellent rotational accuracy, critical properties in applications such as Coordinate Measuring Machines (CMMs) and micro-machining. 

Linear Bearings

This is another unique type of bearing, which is extremely popular for linear motion applications. These bearings are defined by movement along a straight line, often on shafts or rails, and using recirculating ball bearings. 

Linear bearing

Magnetic Bearings

These are bearings that support loads and ensure smooth movement or rotation using magnetic forces. The setup for these bearings could be 100% magnetic or contain conventional bearing configurations. While there are many varieties of these bearings, Active Magnetic Bearings (AMBs) are the most widely used. 

Fluid Bearings

Fluid bearings are a special class of bearings that use a thin layer of lubricating fluid. Such bearings, which mostly rely on oil, are present in applications such as satellites, power generators, gas turbines, automotive, and aerospace industries.

Fluid bearing 

Type Of Bearing 5: Mounted Bearings

Mounted bearings, or bearing units, come pre-assembled, complete with a bearing housing. They are designed for easier installation and maintenance, and their housings are mostly made from stainless steel or cast iron.

Popular versions of mounted bearings are flange block, hanger bearing, and pillow block. 

Flange Bearing

Flange bearing

This mounted bearing type features a ball bearing insert and a flanged housing. Its housing is not only important for mounting but also for protecting the bearing from contaminants when being used in HVAC, material handling, and related applications. 

Hanger Bearing 

Hanger bearing

True to its name, the hanger bearing is designed to hang on drive shaft assemblies, especially in aerospace and automotive applications. It is best or most popularly paired with screw assemblies. 

Pillow Block Bearing

Pillow block bearing

The mounting holes of the pillow block type of mounted bearing are perpendicular to the shaft. The bearing’s robust design from pressed steel and cast iron is perfect for industrial applications. 

How To Choose Different Types Of Bearings 

The choice of a bearing affects the performance and durability of machinery. Therefore, it makes sense to exhaust all the factors before deciding what kind of bearing to provide or use. 

Considering all the options we have outlined above, factors such as operating conditions, nature of the load, accuracy, and rigidity are important in the selection process. 

Speed Range

The speed of rotation or movement is a critical consideration for all types of bearings. A bearing meant for high speeds is usually designed with matching materials, shapes, and orientation. Generally, roller bearings are for slower applications, while ball bearings can support high-speed applications. 

Working Conditions 

Working conditions refer to all the elements, weather-related and artificial, that may affect bearing performance. Is the bearing capable of performing optimally in the presence of heat, dirt, vibrations, moisture, and such? 

Temperature, for instance, can alter material properties and lubrication effectiveness. A bearing to be used in high-temperature environments must be engineered to withstand it. 

Misalignment Tolerance 

In many instances, the bearing is exposed to misaligned components. In that case, the bearing tolerance to such situations matters. Even where there are motor Shaft deviations, the bearing should work optimally. Consider using spherical roller bearings for the best performance in misaligned setups. 

Loading Requirements 

The amount of load and its direction are important considerations for bearing types and uses. This component should support both radial and the accompanying axial forces. Tapered bearings are excellent at handling axial loads, while roller bearings handle large radial loads superbly. 

Further reading: Custom Car Interiors and Manufacturing, Custom Car Interior Materials & Manufacturing

 

Conclusion

If there is a list of unsung heroes of machinery, then the different kinds of bearings are on it. The smooth-running systems with superior efficiency in aerospace components, industrial machinery, and consumer goods, among so many other applications, owe it to these powerhorses. 

At ProleanTech, we recognize the essence of having the right kind of bearing for the application. We have in-depth expertise in CNC precision machining that ensures bearings and other components perform optimally. 

Contact us now to learn how the best machining services can sustain the smooth running of machinery for a lifetime.