Radial ball bearings are friction reduction devices that carry loads radially around its axis.
A molded plastic cage, this cage type is guided by the balls and is suitable for varying running torques and high speeds.
Average running torque is the mean level of torque the bearing is subjected to at a consistent RPM. Bearing speed limitations are almost impossible to conclude from application to application.
The shields and seals of a bearing do not carry a radial load and only light axial loads, if any. A loose fit allows for easy installation, but may also allow the bearing to slip on the shaft or in the sleeve.
Industry standards typically require that 90% of bearings are still serviceable after 1 million rotations, and 50% of bearings still be serviceable after 5 million rotations. Ball bearings types include radial ball bearings (deep groove and angular contact) and thrust ball bearings. Temperature can be regulated by monitoring the oil flow through the bearing and by external cooling.
Starting torque is the measurement of the torque required to initiate rotation of one raceway of the bearing. Peak running torque is the maximum amount of torque experienced by a bearing, but can be difficult to determine. Calculated life of a bearing is based on its load, operating speeds, and environmental factors. Stamped steel is the most common retainer material; stamped bronze or brass is readily available in many European countries. Rubbing of the mechanical parts, as well as oil shearing, contribute to a ball bearing's heat generation. Conveyor belts will use radial ball bearings to provide frictionless rotation of traction wheels.
This bearing can handle considerable radial and axial load, but is not intended for pure thrust applications.
As part of its continuous effort to improve the performance capabilities of its rolling bearings, NKE researches surface coating technologies and uses alternative cage materials.


In order to improve the performance of radial cylindrical roller bearings and radial deep groove ball bearings in particular, for demanding operating conditions NKE uses a cage made from high strength material with an amorphous carbon coating, the DLC coating with NKE suffix SQ202. Quality radial ball bearings are subject to standards, which indicate their precision and efficiency.
Other specialty bearing cages and retainers are manufactured, often of supplement styles to receive additional benefits.
Miniature bearings and instrument bearings carry moderate radial and thrust loads at low operating torque while providing high performance in a small envelope design.
These ball bearings are available with cylindrical or tapered bores in diameters ranging from 5mm to 130mm.
This means four variables need to be accounted for to determine working loads for a bearing. 440C stainless steel and SAE 52100 steel are the most common materials for raceway and ball designs, but these alloys are not suitable for operating or friction temperatures above 350° F. These steel cages coated with DLC are tougher and last longer than the standard, uncoated brass variants, and are ideally suited to harsh operating conditions. Bearings that are used in machines with high radial accelerations, centrifugal forces or vibrations are typically equipped with inner-ring or outer-ring guided, primarily one-piece, solid brass cages in order to minimise any undesirable effects the cage may have on the motion characteristics of the rolling elements.
This increases resistance to breakage and lowers the coefficient of friction between the rolling bearing shoulders and the cage, helping to prevent premature wear or abrasion especially in applications where lubrication is difficult. The service life of bearings was extended considerably, and mechanical failures were eliminated altogether. Radial ball bearings are manufactured in many configurations to suit a variety of applications.
Bearings without shields or seals, called open bearings, should be employed if externally sealed and the operating conditions permit. Needle roller bearings are a type of radial roller bearing with rollers whose length are at least four times their diameter. By revising the cage materials and assembly, the bearing becomes better suited for certain applications. High temperatures can have adverse effects on bearing materials if they are not approved for high-heat use. Frictional heating is a result of bearing pressure, rolling velocity, and the coefficient of friction.


Other bearing components besides cages can also be treated with the amorphous carbon coating. Examples of typical applications include big end bearings, fast accelerating gearboxes or generator systems.
The material of choice for the cage is steel, and depending on the design of the bearing the cage may be machined solid steel with inner or outer ring guidance. One of the most important properties of the coating is that it prevents wear and thus also the abrasion particles that become trapped by the lubricating grease in the bearing. When compared directly with uncoated brass cage variants, the steel cages with the SQ202 coating offer clearly superior performance in terms of wear and strength in harsh application environments.
Molded synthetic rubbers operate in a similar fashion to regular rubber bearing seals, but have higher operating temperatures and have better chemical resistance properties. Roller bearings are used in rotary applications to replace sliding movement with low friction, rolling motion. This results in no accountable impact on the inner raceway, but this type of bearing cannot be cleaned or receive additional lubricant, which is usually grease. Although solid brass cages are an acknowledged standard, they are still subject to certain operating limits. Polytetrafluoroethylene (PTFE) seals are connected to the bearing by a groove in the outer raceway.
Dry films are difficult to apply and produce wear flakes as the bearing rotates, possibly obstructing bearing operation. In applications with heavy loading, excessive wear, abrasion of the cage guide surfaces or even mechanical failure can occur.
It helps to prolong the service life of bearings significantly in extreme operating conditions. Loads for ball bearings are subject to static or dynamics loads, as well as axial or radial loads.



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