Needle bearing vs Ball bearing- Their common
Rolling bearings are composed of orbital rings (inner ring and outer Rings), rolling elements (balls), and cages.
That is, several rolling elements are arranged between two opposite track rings, and the retainers are used to prevent them from contacting each other and keep a certain interval for rolling motion.
The geometry of the rolling elements and the raceway surfaces of the inner and outer rings is point (ball) or line (roller) contact. Theoretically, the rolling elements roll and revolve on the inner and outer rings.
The main feature of the bearing is to help reduce friction. Bearings reduce friction by rolling two surfaces against each other, thereby reducing the amount of friction created. They consist of a smooth metal ball or roller that rolls on smooth inner and outer metal surfaces. The wheel or ball is loaded, causing the device to spin.
The contact surface (point) of the rolling element and the track ring support the load on the bearing with its track surface. The other constituent part retainer does not directly bear the bearing load. In addition to maintaining the correct position of the rolling elements at equal intervals, it also prevents the rolling elements from falling off when the bearing is installed.
The load of the bearing includes radial load and thrust load. Depending on where the bearing is in the mechanism, it can see all radial or thrust loads or a combination of the two.
Rolling bearings are mainly divided into two categories: ball bearings and roller bearings according to the shape of the rolling elements. Compared with ball bearings and roller bearings with the same main dimensions, ball bearings are suitable for high-speed, high-precision, low-torque, and low-vibration applications due to their lower frictional resistance and shaft runout during rotation. Because there are many forms and types of rolling bearings, each has its inherent characteristics.
Compared with sliding bearings, it has the following common advantages:
(1) The starting friction coefficient is small and the difference with the kinetic friction coefficient is small.
(2) There are international unified standards and specifications, and it is easy to obtain interchangeable products.
(3) Easy to lubricate and less lubricant consumption.
(4) A bearing can bear radial load and shaft at the same time as the load.
(5) It is also easier to use at high or low temperatures.
(6) Bearing rigidity can be improved by applying preload.
Needle bearing vs Ball bearing -Ball-bearing structure and features
The ball bearing is a type of bearing that contains a ball to maintain the clearance between the bearing races. The motion of the ball reduces the friction compared to flat surfaces sliding against each other.
The ball bearings have the following types:
- Radial bearing
- Thrust ball bearing
- Deep groove bearing
- Self-aligning ball bearing
- Angular contact bearing
Among the ball bearings, deep groove ball bearings are the most commonly used bearings. The inner and outer ring tracks are arc-shaped deep grooves, which can bear radial load, bidirectional axial load, or their combined load, and are also suitable for high-speed rotation.
In this type of bearings, there are grease-filled bearings (double-covered or double-sealed bearings) and bearings with retaining rings, etc., so the use of these bearings can simplify the design of the bearing shell (box).
Most commonly, one race is connected to a rotating component (such as a shaft or hub) while the other race is fixed. When the race rotates, the ball also rotates. Due to the ball rotation, the coefficient of friction is less than the two flat surfaces rubbing against each other.
These controllers have a small contact area between the races and the ball. Therefore, the load-carrying capacity of ball bearings tends to be lower than that of other types of bearings. Though, these controllers could bear some misalignment between outer and inner races.
However, one of the disadvantages of ball bearings is that the ball “flattens” over time and can eventually fail if the outer race is bored to excessive pressure.
Hence, you must regularly check the rated load and other parameters.
Needle bearing vs Ball bearing -What are needle bearings?
A needle roller bearing is a special type of roller bearing that uses long, thin cylindrical rollers resembling needles. Compared to ball bearings and ordinary roller bearings, needle bearings have a greater surface area in contact with the races, so they can support a greater load.
Needle bearings are roller bearings with rollers that have high length-to-diameter ratios.
Compared with the roller bearing, the needle roller diameter of the needle roller bearing is smaller than that of the roller bearing, but the length is longer.
Compared with general rolling bearings, needle roller bearings have a smaller section-height-to-space ratio, and their load-bearing capacity and rigidity are significantly improved.
A needle roller bearing is thus able to withstand 2 to 8 times more load than ball bearings or cylindrical roller bearings of the same shaft diameter, all this in a small space.
At the same time, they are suitable for rocking motion due to the small inertial force caused by rotation. Needle roller bearings are suitable for lightweight, small machine designs, and they can also be used to replace plain bearings.
Needle roller and retainer assembly is the main type of needle roller bearing, which includes a needle roller and a mechanical retainer that supports it. In space-required miniaturized designs, the shaft and bearing housing (box) itself act as a bearing ring. It is often used in reciprocating compressors and small engine connecting rod bearings, especially the design of the retainer can be used in environments with large changes in speed, acceleration and deceleration, high temperature, and poor lubrication conditions.
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