What is Bearing?- Parts, Types, and application

What is Bearing?

Bearings play a crucial role in machines, basically making it possible for parts to move smoothly relative to one another. In general, you’ll find two main categories: contact bearings and non-contact bearings.

Contact bearings, as the name suggests, involve direct physical interaction with the equipment. Think of examples like sliding bearings, rolling bearings, or even flexural types they all rely on surfaces touching or rolling against each other.

On the other hand, non-contact bearings operate differently. These include designs that use a layer of liquid or air, sometimes even a mix of phases, or rely on magnetic forces to support movement. Because there’s no actual physical contact, issues like static friction are effectively sidestepped something you can’t avoid with traditional contact types.

At its core, a bearing is designed to restrict movement to only what’s wanted nothing more, nothing less. It helps reduce friction between the moving parts, making things run more efficiently.

For example, a bearing might allow something to slide in a straight line, spin freely around an axis, or, in certain setups, completely prevent a type of motion by managing the way forces act on the moving components.

Most of the time, the whole point of having a bearing is to get that desired movement with as little friction as possible. Bearings are usually sorted based on how they operate, what kinds of movements they allow, or the direction of the forces they’re built to handle.

How Does a bearing work?

Bearings play a crucial role in minimizing friction by using smooth metal balls or rollers that move between equally smooth inner and outer metal surfaces. These balls or rollers essentially support the load and let the moving parts rotate with ease.

Think about it so many machines we rely on every day only work as well as they do because of bearings. Without them, parts would wear down quickly due to friction, and we’d constantly be fixing or replacing components. Rolling motion, as you might have noticed, takes much less effort than sliding. This is why the wheels on your car act a lot like oversized bearings.

Just imagine if your car had skis instead of wheels. Getting it to move down the street would suddenly become a lot more challenging! Bearings make sure things keep rolling smoothly, saving us from a lot of unnecessary work.

Bearing loads

Bearings are generally subjected to two main types of loads: radial and thrust. The specific loading a bearing encounters depends entirely on its application. In some scenarios, a bearing might deal exclusively with radial loads, in others just thrust loads, and sometimes it handles a mix of both.

Take the example of an electric motor paired with a pulley. In this setup, the bearings are exposed primarily to radial loads. This is mostly due to the tension in the belt that connects the pulleys, which pulls directly across the bearing’s axis rather than along it.

On the flip side, consider the bearings found in barstools or lazy Susans. Here, the situation is the opposite they experience pure thrust loads.

The reason is pretty straightforward: all the weight from whatever is on top gets pushed straight down through the bearing, with little to no side-to-side force involved.

Now, if you look at the bearings inside a car’s wheel hub, things get a bit more interesting. These bearings have to manage both radial and thrust loads at the same time.

The car’s weight pressing down provides the radial load, while the thrust load comes into play when you take a corner—the sideways forces generated while turning are absorbed by the same bearing.

Parts of a Standard Bearing

The standard essential components of a bearing are as follows:

1. Inner Ring

The inner ring, which is the smaller of the two rings in a bearing assembly, features a groove along its outer edge. This groove acts as a raceway, guiding and supporting the movement of the balls within the bearing.

What sets the inner ring apart is the precision with which its outer surface is finished. The path along the outside diameter is manufactured to incredibly strict tolerances and then honed until it’s exceptionally smooth this level of care is crucial for the bearing’s overall performance.

Typically, the inner ring is fitted directly onto the shaft, and as the shaft turns, the inner ring rotates along with it, making it the primary rotating element within the bearing.

2. Outer Ring

The outer ring, which is the bigger of the two rings in a bearing, serves a crucial purpose. Along its inner diameter, you’ll find a groove that acts as a raceway for the balls to roll smoothly.

Just like the inner ring, the outer ring is carefully finished to very precise standards. In most cases, the outer ring remains fixed in place while the bearing operates.

3. Rolling Element (Balls, Cylindrical Rollers, Spherical Rollers, Tapered Rollers, Needle Rollers)

The rolling elements serve an essential function within a bearing they keep the inner and outer rings apart and allow the bearing to rotate smoothly, minimizing friction. Interestingly, the rolling elements are designed to be just a bit smaller than the grooves or tracks on both the inner and outer rings.

Manufacturers pay extremely close attention to the exact size of these rolling elements. Precision matters here: both the dimensions and the surface finish are tightly regulated, often down to the level of micro inches. Even slight variations in these qualities can make a noticeable difference in how the bearing performs.

4. Cage (Retainer)

The cage inside a bearing serves several important functions. First, it keeps the rolling elements apart, making sure they don’t cluster together or rub against each other unnecessarily. By maintaining consistent spacing between the inner and outer rings, the cage helps the bearing operate smoothly.

It also guides the rolling elements along their intended path as the bearing rotates. On top of that, the cage ensures that the rolling elements stay securely in place and don’t slip out of the bearing assembly.

5. Lubrication

Lubricant plays a crucial role among the essential components of a bearing. Its primary function is to minimize frictional losses that occur between the inner and outer rings of the bearing during operation.

By ensuring a smooth layer between these moving parts, lubrication not only reduces wear but also helps maintain the bearing’s efficiency and lifespan.

6. Other Optional Bearing components

In addition to the main components, ball bearings can also include shields and seals, which play a significant role in boosting both the performance and lifespan of the bearing.

Depending on what the customer needs, these extra features can be incorporated to provide added protection and ensure the bearing functions more efficiently over time.

7. Shields

A shield, in this context, is basically a thin, shaped metal disc that’s been stamped out and given its profile. It’s designed to fit snugly into a tiny groove along the inner edge of the bearing’s outer ring. Even after it’s pressed in, there’s still a small gap left between the shield and the outside diameter of the inner ring.

The important thing here is that the shield doesn’t actually touch the inner ring. This lack of contact means there’s no extra friction introduced between the shield and the bearing itself, which is why these bearings run with impressively low torque.

Shields mainly serve as a first line of defense, stopping larger contaminants from getting inside the bearing. They don’t seal everything out, but they do help keep out the bigger debris that could cause problems.

8. Seals

The seal is carefully positioned within a narrow groove located along the inner edge of the outer ring. Its inner edge is shaped into a uniquely engineered lip profile to ensure a precise fit.

Types of Bearings

• Rolling Element Bearings
• Ball Bearings
• Deep Groove Ball Bearings
• Angular Contact Ball Bearings
• Self-Aligning Ball Bearings
• Thrust Ball Bearings
• Roller Bearings
• Cylindrical Roller Bearings

#1. Rolling Element Bearings.

Rolling element bearings make use of either balls or cylinders as their rolling elements. If you’ve ever tried to push a heavy object across the floor, you’ve probably noticed it’s much easier to roll it than to slide it.

That’s because rolling friction is significantly lower than sliding friction a simple, yet crucial concept at play in these bearings.

These bearings are designed to allow machine parts to rotate freely and smoothly. Interestingly, even in cases where a system requires linear movement, it’s often more efficient to use rotational motion and then convert it to linear.

Take escalators or conveyor belts, for example: while the movement you see is straight, the whole thing runs on rollers powered by motors behind the scenes.

The same principle shows up in machines like reciprocating pumps, where a motor’s rotational energy gets transformed into back-and-forth motion using special linkages.

Throughout all these examples, ball bearings play a key supporting role, keeping motor shafts and other moving parts turning with minimal resistance.

What makes rolling element bearings especially effective is how they swap out sliding friction for rolling friction. This shift means that the bearings can carry substantial loads without generating a lot of heat or wear.

Broadly speaking, these bearings fall into two categories: ball bearings and roller bearings, each tailored to suit different applications and load types.

#2. Ball Bearings.

Ball bearings are among the most widely used types of bearings, largely due to their simplicity and versatility. At their core, these bearings employ a row of small, hardened steel balls as rolling elements. These balls are held in place between two ring-shaped metal components, commonly referred to as races.

The design is straightforward: the inner race is allowed to spin freely, while the outer race typically remains fixed in place. This arrangement helps ball bearings minimize friction during movement, making them ideal for applications requiring smooth rotation.

However, because the contact area between each ball and the race is quite small, ball bearings are best suited for handling moderate loads rather than extremely heavy ones.

Despite this limitation, ball bearings are quite capable when it comes to supporting forces in multiple directions. They can accommodate both radial loads (forces acting perpendicular to the shaft) and axial loads (forces acting along the axis of the shaft), and do so in both directions.

In practice, ball bearings are essential for managing both oscillatory and rotational motion. A common example can be found in electric motors, where ball bearings are used to support the shaft.

The shaft needs to rotate freely while the motor housing stays stationary, and ball bearings make this possible with minimal friction and reliable performance.

#3. Deep Groove Ball Bearings.

Among the different types of ball bearings available, this variety is by far the most commonly used. What sets it apart is the way a series of balls is positioned between two races, forming a sort of ring.

These balls are responsible for carrying the load and enabling the races to move smoothly in relation to each other. A retainer is used to keep the balls properly spaced and in place.

One of the standout advantages of this bearing type is its exceptionally low rolling friction. It’s also specifically engineered to minimize noise and vibration, which is why you’ll often find it in applications where high speeds are involved.

Installation is relatively straightforward, and ongoing maintenance is typically minimal. That said, it’s important to handle the installation process with some care especially to avoid denting the races when fitting the bearing onto shafts, since a push-fit approach is required.

#4. Angular Contact Ball Bearings.

In this particular design of ball bearing, the inner and outer races are intentionally positioned at an angle to one another along the axis of the bearing.

This unique arrangement enables the bearing to support significant axial loads coming from either direction, in addition to the usual radial loads.

Because of this angular offset between the races, the bearing is able to efficiently transfer axial forces straight through to the housing. This makes it an excellent choice in situations where precise axial positioning is critical.

You’ll find angular contact bearings in a wide range of machinery everything from farm equipment and automotive systems to gearboxes and pumps especially in setups where high speeds and reliable load handling are essential.

#5. Self-Aligning Ball Bearings.

This particular ball bearing stands out because it can handle misalignment between the shaft and the housing a common issue caused by things like shaft bending or even just mounting mistakes.

What’s interesting about its design is that the inner ring comes with deep grooves, much like what you’d see in deep groove ball bearings. After that, there are two rows of balls nestled inside, followed by the outer ring.

The real trick, though, is in the shape of the outer ring: it’s concave. This isn’t just for show the concave shape actually gives the inner ring a bit of wiggle room, so it can shift and adapt if there’s any misalignment. That way, the bearing keeps things running smoothly even when everything isn’t perfectly lined up.

#6. Thrust Ball Bearings.

Thrust ball bearings are a unique category of ball bearings that are purpose-built to handle axial loads exclusively. It’s important to note that these bearings are not suited for radial loads so if your application involves any sideways force, these aren’t the right choice.

One thing people appreciate about thrust ball bearings is their quiet performance. They run smoothly and are actually well-suited for situations where high speeds are involved.

You’ll find these bearings available in two main types: single-direction and double-direction. Deciding which one to use really comes down to the nature of the load in your system if you’re only dealing with force from one direction, the single-direction type will do the job. If the load can come from both sides, then double-direction bearings are the way to go.

#7. Roller Bearings.

Roller bearings differ from ball bearings in that they use cylindrical rollers, not balls, as their load-carrying elements. For an element to be classified as a roller, its length needs to be greater than its diameter, even if the difference is slight.

One key advantage of roller bearings comes from their design: the rollers make line contact with the bearing’s inner and outer races, rather than just touching at a single point as ball bearings do. This feature allows roller bearings to handle higher loads.

There’s also a variety of roller bearing types available. Choosing the right one depends on several factors, such as the kind and amount of load, the service environment, and whether there’s any risk of misalignment. All these considerations help in selecting the most suitable bearing for a given application.

#8. Cylindrical Roller Bearings.

Among the various types of roller bearings, these are really the most straightforward in design. What makes them stand out is their ability to handle heavy radial loads and run at high speeds something that’s not always easy to achieve.

On top of that, they’re known for being quite stiff, efficiently transmitting axial loads, running with minimal friction, and lasting a long time before needing any attention.

Interestingly, the load capacity of these bearings can be pushed even higher if you skip the use of cages or retainers those are the parts that typically keep the cylindrical rollers in place. Without them, you can actually fit in more rollers, which means the bearing can handle an even bigger load.

When it comes to types, you’ll find these bearings in single-row, double-row, and even four-row configurations. Manufacturers also offer split and sealed versions to suit different applications.

The split variants come in handy when you’re working with hard-to-reach places think engine crankshafts, for example. Sealed bearings, on the other hand, are designed to keep out contaminants and lock in lubricant, which essentially makes them maintenance-free.

When to Use Ball Bearings?

So, let’s outline some of the working conditions that may require a ball bearing.

• Ability to Handle Thrust Loads: One of the key strengths of ball bearings lies in their design, which allows them to handle axial (thrust) loads quite effectively. In situations where these types of forces are present, ball bearings prove to be a reliable choice.
• Not Suited for Heavy Loads: It’s important to recognize that ball bearings are not intended for situations involving very heavy loads. Because the rolling elements are spherical, the force gets concentrated onto just a few small contact points. Over time, this can lead to premature wear or even early failure if the loads are excessive.
• Efficient at High Speeds: Another advantage of ball bearings is their ability to operate efficiently at high speeds. Since the actual contact area between the rolling elements and the raceway is quite small, there is less friction to overcome. This reduced resistance makes it much easier for systems using ball bearings to reach and maintain high rotational speeds.

Selection of bearing type

Selecting a proper bearing for our application is a very important thing. Here is a quick guide for selecting the right bearing.

• For light to moderate loads, ball bearings are generally the go-to option, while roller bearings are preferred when the loads get heavier.
• If the shafts aren’t perfectly aligned, self-aligning ball bearings or roller bearings are typically chosen to compensate for any misalignment.
• When you’re dealing with medium thrust loads, radial thrust bearings tend to work well. However, if the thrust loads are on the higher side, cylindrical thrust bearings are usually a better fit.
• In cases where there’s a mix of both axial and radial forces, engineers often opt for deep groove ball bearings, angular contact bearings, or spherical roller bearings to handle the combined load.
• For high-speed scenarios, deep groove ball bearings, angular contact bearings, and cylindrical roller bearings are all solid choices because they perform well under those demanding conditions.
• If system rigidity is a top priority like in precision machine tools double-row cylindrical roller bearings or taper roller bearings are commonly used for their sturdiness.
• And finally, if minimizing noise is critical, deep groove ball bearings are generally selected thanks to their quiet operation.

Applications of Bearing

• Aviation Cargo Systems.
• Aerospace Wing Actuators.
• Anemometer.
• ATMs & Card Readers.
• Bicycles.
• Commercial Blenders.
• Dental Hand Tools.
• Electrical Motors.

Advantages of bearings

• These bearings are characterized by minimal friction resistance and reduced power consumption, resulting in high mechanical efficiency and ease of startup.
• Their dimensions follow standardized sizes, making them interchangeable and simplifying both installation and disassembly processes. Maintenance is also straightforward.
• Thanks to their compact construction and lighter weight, these bearings occupy less axial space compared to alternatives.
• They offer high precision, can support substantial loads, and are known for their extended service life.
• Certain types are equipped with self-aligning capabilities, allowing them to automatically adjust to minor misalignments.
• The design is well-suited for large-scale production, ensuring consistent quality and dependable performance, alongside high manufacturing efficiency.
• The friction torque during operation is significantly lower than that found in fluid dynamic pressure bearings, which means less heat is generated and overall power consumption remains low.
• Their axial dimensions are smaller than those of traditional fluid dynamic bearings.
• These bearings are capable of handling both radial and thrust loads at the same time.
• Even across a wide range of load and speed conditions, their specialized design enables them to deliver consistently strong performance.

Disadvantages of rolling bearings

• The noise is great.
• The structure of the bearing seat is complex.
• The cost is high.
• Even if the bearings are lubricated well, installed correctly, and well-sealed, and the operation is normal, they will eventually fail because of the fatigue of the rolling contact surface. If you want to learn more about bearings, please don’t hesitate to contact us.

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