Ball Bearings and Roller Bearings: The Differences

Before dissecting the differences between ball bearings and roller bearings, let’s look at why bearings are needed. Shafts are used to transmit power from one point to another. For instance, one end of a shaft is connected to a motor and the other end is connected to a belt or some other component to which you want to transfer power. Because of this movement, the shaft is under different axial and radial loads. These loads could result in possible deflection, both up and down, and jerking of the shaft while moving. These motions create vibrations that can prevent load transfer from occurring properly. To resolve this issue, a continuously moving support is needed. Bearings serve as this support.  

A bearing is a machine part that supports the machine element and allows relative motion between the contact surfaces of the members while carrying a load. Nearly all types of bearings consist of the same basic parts: a set of rolling elements fitted between an inner and outer ring. This arrangement allows the bearings to absorb a load during operation. The bearing will either rotate or roll when a radial load is applied, and bearings are often used to withstand axial/thrust loads as well. If the load is perpendicular to the axis, it is a radial load. If the load is parallel to the axis of the rotating shaft, it is an axial or thrust load. Having been in use for a long time, bearings have evolved over the years into many different types depending on the requirements of an operation.
 
Now let’s look at the difference between the two types. Bearings have three main components: the bearing rings, the rolling elements, and the cage. If the rolling element is spherical balls, they are considered ball bearings. Ball bearings are commonly used in small wheels at higher speeds and lighter loads. They are standardized and sold as assemblies. In roller bearings, the roller element is a cylindrical roller that makes a line contact as opposed to a point contact. They can take on heavier loads and shocks than ball bearings, and are generally disassembled and replaced in parts. Roller bearings are also more sensitive to angular misalignment. In summary, there are five main difference between ball and roller bearings:

1. Ball bearing rolling elements use point contact, while those of roller bearings use line contact.
2. Ball bearings are ideal for high speeds and light loads, while roller bearings are better for shock and impact loading.
3. Ball bearings are often sold as assemblies, while roller bearings are sold disassembled.
4. Ball bearings are mostly standardized, while roller bearings differ from vendor to vendor.
5. Ball bearings are susceptible to fatigue and spalling, while roller bearings are more susceptible to angular misalignment.