A needle roller bearing is a roller bearing that uses long, thin cylindrical rollers resembling needles. Standard rollers are slightly longer than their diameter, however needle rollers typically are four times longer than the diameter. The needle roller bearing is used in many industries, including mining, automotive, railroad, machine tool and aerospace. Source
In comparison to ball and standard roller bearings, needle bearings have a greater surface area in contact with the races to support more loads. They are thinner, so less clearance is required between the axle and the surrounding structure.
Little change has been made in the basic design of needle roller bearings over the past 60 years, but continuous development has led to cage designs with five times the service life and twice the static load capacity.
With the general trend towards reducing weight, space, and energy consumption, needle roller bearings have become the choice for many critical applications.
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Until then, please continue reading for more information on needle roller bearings and their many versatile uses.
It would be advantageous for us to create a series of posts that included the main roller bearings types you may need for your projects. This is the fourth post of the five-part series.
In case you missed it, here's the third article—Tapered Roller Bearings: What You Need to Know.
What is a Needle Roller Bearing?
- The Needle Roller Bearing supports very heavy loads compared to their size thanks to its contact surface developed by the needles mounted in a steel cage.
- Generally, needle roller bearings consist of needle rollers and cages. A cage is placed between two hardened, smooth surfaces to prevent needle rollers from contacting one another, allowing smooth rolling.
- Compared to other ball bearings, needle roller bearings have a smaller radial section height and smaller mass, making them more compact and suitable for applications requiring low inertia forces.
Why Choose This Bearing?
- Needle roller bearings have a smaller diameter difference between the bearing and the shaft, making them more compact.
- These bearings have become quite popular among design engineers and have been recognized for their tech advantages within specific applications.
- This bearing can withstand 2 to 8 times more weight than cylindrical roller bearings or ball bearings of the same shaft diameter, all in a small space.
- Through its small rollers, a needle roller bearing dramatically reduces the friction of rotating surfaces. In applications that require minimal space and weight, the bearing's large surface area in contact with the bearing's raceway journals creates an advantage. The needle roller bearing is strong, despite its compact design.
- Their size makes them cost-effective compared to other alternatives.
- Comparatively, needle roller bearings have a smaller diameter difference between the bearing and the shaft, making them more compact.
Needle roller bearings must comply with the standards outlined for the roller bearing.
- The accompanying standards may be helpful when considering needle roller bearings. A wide variety of needle roller bearing standards are available from the IHS Global Standards Store.
- ASTM F2162 - Standard Specification for Bearing, Roller, Needle: Drawn Outer Ring, Full Complement, Without Inner Ring, Open and Closed End, Standard Type
- ASTM F2163 - Standard Specification for Ring, Bearing, Inner: for Needle Roller Bearing With Drawn Outer Ring
- ISO 281 - Rolling Bearings - Dynamic load ratings and rating life
- ISO 3031 - Roller Bearings - Thrust Needle Roller and Cage Assemblies, Thrust Washers - Boundary Dimensions and Tolerances
- ISO 3096 - Rolling Bearings - Needle Rollers - dimensions and tolerances
Most commonly used in automobile, machine tool, construction, and agriculture components, including transmissions, compressors, pumps, torque converters, suspensions, U-joints, and rocker-arm pivots. They also can be found in domestic appliances such as pump clutches, portable power tools, and spindles.
Among the many applications of needle roller bearings are automotive transmissions, two- and four-stroke engines, planetary gear sets, and air compressors. In machinery that requires high temperatures, oversized loads, durability, and quiet operation, needle roller bearings are particularly useful.
Types of Needle Roller Bearings
Although there are different types of bearings with needle-shaped rolling elements, the four main types of needle roller bearings include; caged wheel, drawn cup, precision race wheel, and thrust wheel.
A typical structure consists of an inner wheel or shaft to anchor the part, a cage to hold all the rolling elements, and an outer ring. Choosing the correct needle roller bearing depends on various factors, including the type of load required, the speed required, and the expected temperature limits (higher than ball or sleeve bearings). source
Depending on the activity and the application, needle roller and cage assembly can be integrated between rings. The technical constraints of the industrial markets require needle roller bearings to be available in many forms (cages, bushings, bearings with solid rings, combined bearings, needle thrust bearings, cam followers, etc.). source
The basic load rating of a needle roller bearing must be determined before determining its expected helpful duration.
Bearings should never be hammered into their housings.
When a shouldered housing is required, the housing bore must be deep enough to ensure that the housing shoulder filet and the shoulder face clear the bearing.
Place the stamped end of the needle roller bearing (with identification markings) against the angled shoulder of the pressing tool. To locate the bearing properly in the housing, it is advisable to use a positive stop on the press tool. The assembly tool should have a leader or pilot to start the bearing true in the housing. source
Before selecting a needle roller bearing, engineers should consider various factors during the design phase: type of load, speed, misalignment, load capacity, lubrication requirements, temperature, service life, and more.
Rolling cylinders with small diameters held between a single race and a bearing shaft, needle roller bearings are one of the most economical bearings available.
As well as reducing friction, it also reduces wear on the rotating surfaces. Due to their design, these bearings are quite light and small, making them ideal for applications that require less space. The wide range of advantages makes this type of bearing famous among design engineers.
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p.s. Stay tuned for our Ceramic Ball Bearings post next. Ceramic Ball Bearings can replace steel ball bearings because of their higher hardness, meaning they are less susceptible to wear and tear, resulting in a longer lifetime.