Friction is reduced by bearings. When metal contacts metal, friction is high that degrades the metal by adding to wear and tear. Bearings help reduce the friction by allowing the two surfaces to roll over one another.
Let’s compare roller bearings and ball bearings!
What Are Roller Bearings?
Like ball bearings, roller bearings are designed to minimize friction while carrying a load.
Rather than balls, roller bearings use cylindrical rollers to transmit loads while keeping the moving components of the bearings separated.
Bearings of this type may include a single row of rolling elements or multiple rows; multiple rows enhance the capacity to carry radial loads.
Roller Bearing Types
1. Thrust roller bearings
Thrust tapered roller bearings
In these bearings, tapered rollers are used for thrust.
Bearings of this type consist of both housing raceway washers that have ribs and do not have ribs, along with full complement bearings.
Double-row bearings are used mainly for axial load support, such as on-roll necks in rolling mills.
Thrust cylindrical roller bearings
With cylindrical rollers for a larger load capacity, these bearings are available in a single-row, a double-row, and a three-row configuration.
Only axial loads can be supported, they can support high loads, and they have excellent axial rigidity.
Thrust spherical roller bearings
With a barrel-shaped rolling element that allows them to self-align, they can handle axial hush loads.
They have a spherical surface which is where the housing raceway washer or outer ring is with a spherical surface on which the raceway surface of the housing raceway washer (outer ring) is situated in the middle of the guiding sleeve.
Thrust needle roller bearings
These are bearings that have machined parts and use pressed steel plates for the washer. They use the latter type with the high load-bearing and smallest cross-sectional height.
2. Radial roller bearings
Double row cylindrical roller bearings
Cylindrical roller bearings with two rows are intended for heavier loads than single-row bearings cannot handle. Also, radial loads can be increased with additional rows of rollers.
Tapered roller bearings
All roller bearings can support radial loads as well as axial loads in one direction. Tapered roller bearings are the most common type.
Tapered roller bearings are used to support axial loads in both directions.
Cylindrical roller bearings
Their rolling elements are cylindrical rollers. A cylindrical roller bearing can withstand even greater radial loads than a deep groove ball bearing and is used in machines where there will be heavy impact forces.
Spherical roller bearings
The rolling elements of these devices are convex barrel rollers. There are two raceways: an outer spherical surface and a central spherical surface.
A spherical bearings inside ring, cage, and rolling elements, can take on an inclined rotation.
Needle roller bearings
The rolling elements of these devices are needle rollers. In contrast to cylindrical rollers, needle rollers are smaller in diameter and so their bearings are also smaller in cross-section height, contributing to the downsizing of machinery.
Double row tapered roller bearings
In addition to accommodating heavy radial loads, these bearings have a high level of torsional rigidity and are capable of handling axial loads.
These bearings often find application in gearboxes, rolling mills, hoisting equipment, and mining machinery.
What Are Ball Bearings?
A ball bearing is a rolling-element bearing that uses balls to separate and keep a gap between its races. Rotational friction is reduced with axial and radial loads which are supported simultaneously.
1. Thrust ball bearings
Double direction angular contact thrust ball bearings
A large contact angle ensures the elements are rigid in the axial direction so they are capable of supporting axial loads in both directions. Grease-lubricated vertical shafts are not suitable for their structure.
Single direction thrust ball bearings
A cage encloses the bearing balls between the inner ring of the shaft raceway washer and the housing raceway washer that corresponds to the outer ring. Axial loads may only be applied in one direction.
High-speed duplex angular contact ball bearings
Parallel duplexes (DF) can only handle axial loads in one direction. Angular ball bearings with double directions of the thrust are better in terms of high-speed properties but have low axial stiffness.
2. Radial ball bearings
Double row angular contact ball bearings
Angular contact ball bearings are arranged in a back-to-back configuration, known as duplex (DB) bearings, combining the inner and outer rings.
The rods can support radial loads and bidirectional axial loads, and moment loads.
Duplex angular contact ball bearings
Angular ball bearings in three-way tandem arrangements, back-to-back arrangements, face-to-face arrangements, or stacked arrangements are called tandem bearings.
The back-to-back duplex (DB) and face-to-face duplex (DF) bearings can handle axial loads in either direction.
Ball bearings for rolling bearing unit
Both sides of the seal are covered with synthetic, oil-resistant rubber seals, and the unit is equipped with a unique slinger.
Included are those with an inner ring of a wide diameter that is screwed onto the shaft, with mounting balls in two areas, and those with a bore tapered caliber surface and are attached with an adapter.
Deep groove ball bearings
This is the most common type of bearing in a wide variety of applications. For ease of use, these bearings feature grease-enclosed seals and shields.
Four-point contact ball bearings
There are two inner rings in these angular contact ball bearings. During radial movement of the inner and outer ring, four points of both rings come into contact with the balls.
Self-aligning ball bearings
With these ball bearings, the track surface on the outer ring is spherical. The inner ring consists of two rows of grooves, the center of which matches the center of the bearing. The balls, inner ring, and cage can rotate independently of one another as well as tilt to a certain extent.
Roller Bearing vs Ball Bearing: How Do They Differ?
With ball bearings, two factors determine the distribution of sliding speed: the contact ellipse’s spatial curvature and the effect of spinning.
In tapered roller bearings, neither of these torque contributions occurs. On the other hand, tapered roller bearings experience a roller/rib torque, which is analyzed with the previous two components of hall torque.
The bearing consists of two racing rings that accommodate rolling elements. As the race elements move relative to one another, they roll easily and without slipping.
It has a finite pressure and a finite size of contact between ball and race. Due to the different speeds of the individual parts of the deformed ball, as it rolls, the ball does not roll smoothly.
Contact between the inner and outer rings
As a sphere, the ball only makes contact with the outer and inner races at a very minute point, which makes spinning it extremely smooth.
Bearings with rollers that are cylinders have a line rather than a point at which they contact the outer race. Consequently, more load can be applied to the outer race.
Load spreading area
A roller in these bearings is cylindrical, so there’s no point where the outer and inner races come into contact. A bearing can handle much greater loads than a ball bearing because the load is spread over a larger area
Able to handle thrust and radial loads and tend to be used for applications with a relatively low load.
When the contact area is very small and your bearing is under excessive load, the balls will deform and squish, causing the bearing to malfunction.
The loads are distributed over a larger surface area, so the bearing can withstand much higher loads as compared to a ball bearing. It is not intended to handle thrust loads.
When to Use Roller Bearings?
You don’t need high-speed operations
Roller bearings suffer from a lot of friction due to their large contact area. In addition to generating heat, excessive friction also leads to deterioration and wear, which negatively affects equipment. In this sense, roller bearings are designed for slower rotation speeds and are under highly controlled conditions.
You are designing for heavy load operations
Roller bearings are characterized by the fact that their contact area is greater – by orders of magnitude greater than the ball bearings. The load is distributed evenly so the roller bearings can handle heavy loads.
You are willing to spend more for precision-made parts
There is only one axis of rotation for roller bearings. An out-of-alignment bearing element has become out of line with the load direction, so it won’t be able to rotate. Therefore, roller bearings require more precision when designed, so they are also pricier.
When to use ball bearings?
You are designing equipment for lighter loads
Oscillatory and rotational motions are controlled by ball bearings. The shaft is connected to the motor housing with ball bearings for electrical motors with a free-rotating shaft but a fixed housing.
You need greater freedom of movement
Whether the load is radial or thrust, a ball bearing will rotate. As a result, ball bearings are ideal for items with no control over the input, such as items designed to be used by humans.
You need to operate at greater speeds
The advantage of ball bearings and small contact areas is that friction is reduced significantly, which makes them ideal for high-speed operations. Because of the low friction, the spherical elements rotate with less resistance reducing wear and tear.
1. Can ball bearings rust?
Ans: All chrome steel bearings are prone to rust, so the outer surface has a protective oil coating. However, when in contact with certain substances, stainless steel bearings will still rust.
2. Is a ball bearing the same as a steel ball?
Ans: Ball bearings were known as steel balls many years ago. Despite what many people think, a steel ball can be called a “steel ball” in the bearing trade, while a “ball bearing” is an assembly including the inner ring, outer ring, along with balls in between.