Introduction
Bearings have been around for centuries, but in the modern world, their importance is perhaps even greater than it was at the time of their invention. Low friction and high precision bearings are the driving force behind machine tools, industrial robots and precise instruments, which together provide the necessary automation and accuracy. Bearings perform a key role in providing the necessary rotational and linear motion of components to keep machines operating in a safe and efficient manner.
Many kinds of bearings are available with different structures and features, which are adjustable to various application requirements. Generally, there are five types of bearings in use: roller bearings, ball bearings, needle bearings, fluid bearings, and journal bearings.
Roller Bearings
Roller bearings are applications where the rotation or linear motion is relatively low. They are shorter and can accept more load than other bearings. The roller is a free-spinning bearing that is typically cylindrical in shape, composed of an outer race(housing) and inner race (roller), separated by a lubrication pocket and buffers. They are typically made of carbon steel, but some special applications may require stainless steel or other materials. The roller bearings are commonly used under heavy loads and have a wide range of uses. The load capacity of a roller bearing is much higher compared to other types of bearings due to its ability to support larger weight.
Ball Bearings
Ball bearings, also known as radial bearings, are the most common type of bearing used in many industries and applications. These bearings typically consist of an inner and outer ring containing several balls. The rings are separated by a lubrication pocket and buffers. The transfer of the load is done through balls which provide low friction, low wear and high precision. The balls are made of hardened steel and they are precision-grade. Ball bearings are used where there is a need for high speed with low friction, such as computer and medical equipment, and are used in a wide range of applications.
Needle Bearings
Needle bearings are ideal for taking higher loads at low speeds. They can withstand medium and high speeds, but can’t bear large loads. Needle bearings are known for their low-friction performance, low bearing failures, minimal noise and vibration and high precision. They are designed with a small diameter and a long slender form. The needle bearing has needle-shaped rollers oriented at a 90-degree angle, which allows the bearing to spin with low friction and high precision.
Fluid Bearings
Fluid bearings are a type of bearing that uses a fluid instead of rolling elements to support the loads. These bearings are often simply referred to as hydrodynamic bearings and are typically used in very high precision applications and high speeds. The use of the fluid helps to reduce the friction between the shaft and the bearing and also helps to dissipate the heat generated while running. These bearings typically consist of a single part, with no rolling elements, which helps to maintain a light weight and reduce noise and vibration.
Journal Bearings
Journal bearings are designed to support both low and high-speed loads. These bearings have the ability to safely accommodate both radial and axial loads. They are constructed of a lubricant-filled pocket, cylinder, and washers. The pocket is filled with oil, grease, or plastic-based liquefied lubricant to reduce friction between the bearing and journal speed. Journal bearings are good for applications that undergo vibration, or when it is necessary to prevent contact between the two components.
Conclusion
Each of these five types of bearings come with advantages and disadvantages. Choosing the right one depends on the application and other requirements. Roller bearings and ball bearings are the most widely used, while fluid bearings and journal bearings are ideal for applications that require higher precision and vibration resistance. Finally, needle bearings are great for applications that require low friction and high load capacity. It is important to choose the right type of bearing for a particular application in order to ensure the efficient, safe and smooth operation of a machine.
