January 15th, 2021
Bushings and bearings: it seems like these two terms are used interchangeably. There is actually a difference between the two, and it is indeed a simple one.
“Bearing” refers to a component that facilitates movement between two parts, while reducing friction. A “bushing” is a specific design of bearing used for specific applications. In short, a bushing is a bearing, but a bearing is not always a bushing.
Now that is cleared up, we will take a closer look at the different types of bearing, and how a bushing differs from its rolling counterparts.
Different types of bearing have the same basic structure and purpose: they have two surfaces that move over each other, enabling mating parts to move easily and without friction. The main difference is whether they are working with rotational or linear motion.
Ceramic or steel balls are fitted between inner and outer rings to create the classic ball bearing. These are designed to support rotating shafts, while reducing friction between the static and moving parts.
These cylindrical or tapered rolling-element bearings have a high load capacity. Stainless steel cylindrical roller bearings take heavy-duty radial loads and are used applications with high speeds. Spherical bearings work at lower speeds and if installed as a double row, can manage both radial and axial heavy loads. Self-aligning, they can deal with sudden shocks and vibration.
Small but robust, needle bearings reduce friction between smaller components, and are often found in domestic appliances which have oscillating parts.
These are mounted bearings that are installed inside bolted-on parts like pillow blocks. They have an eye-shaped head, and their integral flank houses the plain spherical bearing.
The simplest design of bearing, these are also known as plain bearings, journal bearings – and bushings.
Its alternative name of “sleeve bearing” gives you the best idea of a bushing’s use and appearance. The sleeve bearing has a sliding action and because they are usually self-lubricating, they provide a smooth and reliable operation.
The simplest type of bushing is a cylindrical, sleeve-shaped design, and it’s used in radial loads. If you’re working with heavy loads, combine the cylindrical bushing with thrust washers. For axial loads, a bushing with a flange is the best option.
The design may be simple; however, the performance and function of a bushing can vary greatly depending on its material.
Plastic bushings are popular, being a low-cost, low friction and low maintenance option. They are self-lubricating so are good for hard-to-reach parts, and as there is no risk of corrosion, they can be used in wet environments. They have a low coefficient of friction, thus reducing heat, and have a better resistance to shock than their metal counterparts.
Bronze bushings have exceptional durability and a long service life. They do not corrode and do not easily deform. However, bronze bearings do need plenty of lubrication during operation, making them higher maintenance than plastic. Stainless steel is a popular option, either as the sole material or backed onto the plastic bearing surface to add rigidity (this prevents deformation during e-painting).
PTFE (polytetrafluoroethylene) is a high-performance engineering plastic that makes an excellent bushing material. It is low friction, noise-dampening and maintains constant torque. It can be difficult to join, but this is not a deal-breaker with the simple sleeve bearing design, like our NORGLIDE® Bearings.
Before you specify your bearings, speak to the experts at Saint-Gobain, engineer to engineer. We can talk through the different types of bearing and bushing in greater detail, and make sure your application has the optimum bespoke components for the job.