Needle Roller Bearing

Needle roller bearings are durable, compact, and lightweight and are typically preferred over ball bearings when space is limited. They have rollers resembling needles, and their length generally is four times longer than the bearing's diameter. Additionally, like all bearings, the primary function of a needle bearing is to reduce friction between moving parts.

Low Maintenance
Most needle roller bearings don't require daily, weekly, or even monthly maintenance. However, they do need to be kept adequately lubricated. This means choosing the right type of lubricant and ensuring that the proper amount of lubricant covers the rolling elements (needles) of the bearing. Proper lubrication is also essential to keeping dirt and debris out and protecting the bearing against corrosion. Equally important is knowing when to lubricate and how much lubricant to use. The best solution often involves installing an automatic lubrication system so that the bearing receives the correct amount of lubricant at the right time.

Exceptional Axial & Radial Load Capacity
Industrial needle bearings can also withstand high axial and radial loads. This differentiates them from ball bearings, which are typically reserved for applications where high axial and radial load requirements aren't as necessary. Axial loads, sometimes referred to as thrust loads, are forces exerted parallel to the axis, while radial loads run perpendicular to the axis. Needle roller bearings have excellent axial and radial load capacity because they support high loads on the mounting surface (axial direction) and radial direction.

Excellent Rigidity
Rigidity refers to a material's ability to maintain its shape and not deform, bend, or break when a high external force is applied. Industrial needle roller bearings have excellent rigidity, and even a small amount of elastic deformation on a needle roller bearing won't typically affect its operation. Using rigid bearings in tight-fitting applications with high axial and radial loads helps to protect mating surfaces and adjacent parts from friction and excessive wear. The rigidity will vary based on the bearing's size and the type of needle roller bearing used. Factors including the physical space the bearing must occupy, alongside the amount of axial and radial loads the bearing must withstand, should always be considered. Increasing the number of rollers used will increase the rigidity.

Great for High-Speed Applications
Ball bearings generate lower amounts of centrifugal force during high-speed applications. This increases friction, leading to the ball bearing overheating and eventually breaking. Comparatively, needle roller bearings generate a higher centrifugal force with high rotational speeds because the needles are longer and weigh more than the balls in ball bearings. Needle roller bearings also generate high rotation and won't overheat at high speeds, which makes them ideal for high-temperature applications.

Low Coefficient of Friction
Friction occurs when a given material or surface encounters resistance when sliding, moving, or rubbing against another. The coefficient of friction refers to the ratio of friction between the two materials relative to the normal force that would otherwise keep them together.
A low coefficient of friction means that the resistance between the two surfaces is low. Needle roller bearings have a low coefficient of friction during operation. This means that friction is low, and as a result, the bearings won't overheat. It also means the bearings don't require much lubrication to control friction between mating surfaces.

Exceptional Mechanical Properties
Mechanical properties vary based on the material the needle roller bearing is made of. However, for the most part, manufacturers will heat treat a needle bearing to improve its mechanical properties. Heat treatments can increase a bearing's strength, durability, hardness, ductility, elasticity, and wear resistance. Since the needle roller bearing will be in contact with other metals, increasing its hardness, tensile strength, ductility, and wear resistance through heat treatment helps to extend the life of the bearing while protecting any mating surfaces. This leads to a stronger, more durable bearing that lasts longer and requires fewer replacements.

Understanding the distinct advantages of needle roller bearings compared to traditional ball bearings is crucial when selecting the right bearing for a specific application. Needle roller bearings offer several key benefits due to their unique design and functional properties:

1. Needle roller bearings have longer and narrow rollers, which increase the contact area with the mating surface. This design enables them to support higher radial loads than ball bearings of the same size. The SKF NA 4900 series, for example, is engineered to accommodate heavier loads without increasing the bearing's radial size.

2. Needle roller bearings are designed to reduce friction by minimizing surface contact with raceways, unlike ball bearings. This design characteristic allows bearings like the INA NK series to operate at higher speeds with less heat generation, making them ideal for applications where temperature regulation is a concern.

3. Needle roller bearings are designed to achieve higher stiffness and greater accuracy in operation, making them ideal for precision applications. The FAG NK series is often used in robotic arms or medical equipment due to its high precision and rigidity.

It's important to measure needle roller bearing dimensions and choose the correct bearing type when designing a new system, replacing a damaged bearing, upgrading an existing system, or changing the application of a system. Choosing the right needle roller bearing ensures proper fit and function, improves efficiency, and prolongs the system's lifespan.

Step 1: Determine the load and speed requirements
Before measuring needle roller bearing sizes and choosing the correct bearing type, it is crucial to recheck and determine the load and speed requirements. This helps to select a proper needle roller bearing that can handle the specific requirements of the system and ensures proper function, longevity, and efficiency. For example, a high-speed application will require a needle roller bearing that can handle the high rotational speeds without excessive heat buildup or wear. Similarly, an application with a heavy load will require a larger needle roller bearing to support the weight without prematurely failing.

Step 2: Measure the needle roller bearing sizes
Once you know the load and speed requirements, you'll need to identify the bearing dimensions. About how to measure bearing sizes, here are common ways:
(1) The reference number
The quickest way to determine the correct type is to use the reference number. Most needle roller bearings have these numbers engraved on them, but over time they may become difficult to read or rub off completely. In these cases, you'll need to measure the bearing yourself to get an accurate match.
(2) Accurate measurement of needle roller bearings
To measure a needle roller bearing in a good way,you'll need to determine its width(W), inner diameter(ID), and outside diameter(OD). To get an accurate reading, measure at the widest point for OD and measure at the narrowest point for ID and measure W between the two bearing rings. You can do this with a vernier caliper or a ruler, making sure to measure with precision. Once you have these measurements, you can use our bearing search tool to do bearing search by dimensions.

Step 3: Choose the appropriate needle roller bearing type
There are several needle roller bearing types available. Each type is designed for a specific application, so it's important to choose the appropriate type for your needs. Once you measure your needle roller bearings, you can use our search to find the corresponding bearing type. This is known as the suffix in the bearings reference.
e.g. Inside Diameter: 12mm; Outside Diameter: 18mm; Width: 16mm - Bearing Type: HK1216
But that's not all – needle roller bearings also have suffixes indicating the presence of seals.
E.g. 2RS= 2 Rubber Seals=double seal
Another important suffix to consider is the bearing clearance value. This determines the amount of room between the bearing races and can affect how the bearing performs in certain conditions. This clearance is necessary to accommodate any thermal expansion that may occur during operation, as well as to ensure that the bearing operates smoothly and efficiently. For example, if a bearing is likely to get hot, a larger clearance may be necessary to allow for heat expansion.
C2 = Clearance is less than international standard
No Markings = Standard Clearance
C3 = Clearance is greater than international standard
C4 = Clearance is greater than C3
It is important to choose the correct clearance for a needle roller bearing based on the application requirements. Too much clearance can cause the needle roller bearing to vibrate excessively, while too little clearance can cause the bearing to overheat and fail prematurely.

Carrying capacity
Generally, under the same external dimensions, the bearing capacity of the needle roller bearing is 1.5-3 times that of ball bearing, so when a large load or impact load is applied, roller bearing can be selected preferentially. However, when the diameter is less than or equal to 20mm, the bearing capacity of the two is similar, and the price of ball bearings is lower than roller bearings, so ball bearings are preferred.

The speed cannot exceed the limit speed
An excessive rotation speed of the rolling bearing will increase the temperature between the friction surfaces, resulting in high heat. In this case, the lubrication of the two metal surfaces fails, and the rolling elements will be damaged by gluing.
When designing, if the rotational speed of the rotating shaft is known, when selecting a rolling bearing, we must make the limiting speed more excellent than the rotational speed of the shaft, so that the rolling bearing is safe.

The allowable range of angular deviation
Due to the installation error of the bearing or the deformation of the shaft, the centerline of inner and outer rings will be relatively inclined. The angle of inclination is called angular deviation. If the angular difference is too significant, it can even affect the regular operation of the shaft. At this time, you can choose a spherical bearing, such as a spherical ball bearing or a spherical roller bearing. The self-aligning bearing outer ring raceway is a spherical surface centered on the bearing center, so it can automatically align itself. Thrust ball bearings and needle roller bearings do not allow angular deviations. Thrust ball bearings can only support axial loads, and the load line of action must coincide with the axis. If there is an angular deviation, the thrust ball bearing will be severely damaged. The rolling body of the needle roller bearing is in line contact with the outer ring and is most sensitive to the axis deviation. It should be avoided when the axis is skewed.

Needle roller bearings, like other types of bearings, play a big role in how efficiently your machines operate. Any debris or dirt that contaminates the Needle Roller Bearing will eventually cause premature wear and tear, which may result in mechanical failure and/or roller misalignment.
Since bearings are also not resistant to corrosion or oxidation. The environment in which needle roller bearings operate will also affect their performance and lifecycle. Bearing failures are more common when the bearings are exposed to wet environments and corrosive chemicals, or if lubricated with low-quality grease.

Step 1: Selecting the Right Lubricant
Lubrication is needed on the rolling elements of Needle Roller Bearings to reduce friction, prevent corrosion and contamination, and to extend the overall life of the bearing and other components.
There are mainly two types of lubricants: Grease and oil. Grease lubricants are often used to lubricate needle roller bearings, but oil lubricants are needed for high-speed or high-temperature applications.
When selecting the right type of grease lubricant, consider the formulation of the product, including any thickeners and additives, then choose the right product for the bearing's operating conditions. Grease lubricants are typically given an NLGI (National Lubricating Grease Institute) grade number which is measured by the worked penetration range.

Step 2: Lubricating Your Needle Roller Bearing
When it comes to Needle Roller Bearing maintenance, the most common mistake is using the wrong lubrication method. This can actually negatively impact the overall life of the bearing.
You can lubricate bearings either manually or with an automated system. We recommend using an automatic lubrication system for better efficiency.

Step 3: Knowing When to Relubricate
One of the most common lubrication mistakes is applying oil or grease lubricant when it's not needed.
Knowing when to relubricate is just as important as knowing what type of lubrication to use. You should not lubricate bearings every month or week.
Typically, relubrication intervals will not be time-based, but instead depend on the performance of the system and the operating environment. You should monitor friction levels and lubricate your bearings depending on the specifics of the application, including load size, speed, and the type of bearing you have.

Step 4: Ensuring Proper Mounting
Before mounting your Needle Roller Bearings, it's important to understand the assembly tolerances. The most common fitting practice is J6/H7 clearance and fit guidelines. It's also important to select the right type of shaft.
Universal Bearings can machine custom shafts that are designed for your specific Needle Roller Bearing, so you'll never have to worry about selecting the right shaft size and type.
Bearings with cylindrical bores are typically mounted using the press fit method or with a hammer and mounting sleeve. If it's a large bearing, you will need to heat the bearing first. Bearings with tapered bores are mounted on a tapered or cylindrical shaft with an interference fit. You typically use an adapter or withdrawal sleeve for mounting. The types of tools you'll need depend on the mounting procedure, bearing size, and seat type.
After mounting, we recommend performing an inspection to ensure proper mounting of your Needle Roller Bearing.

Step 5: Continually Inspecting for Signs of Damage
You also need to frequently inspect your bearings for signs of wear and tear and other damages.
We recommend creating a Needle Roller Bearing maintenance program for your plant. This will ensure that your employees understand when inspections should be performed and how often bearings need to be relubricated.
The most common causes of bearing failures are improper lubrication, contamination, improper mounting, and fatigue.
These following signs of damage indicate that a bearing may not have been properly installed or maintained:
• Flaking on Raceway
• Peeling or Cracks
• Spalling (Scratches)
• Smearing (Rough Surface)
• General Wear (Rough & Scored Surface)
• Discoloration
• Rust & Fretting
• Skewing Rolling Element
The solutions to these depend on the cause. Whether the failure was caused by improper installation/mounting, improper lubrication, or unfavorable operating conditions, correcting the condition is critical to proper machine operation and employee safety. 

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