Bearing FAQ

Please feel free to scroll down the list of frequently asked bearing questions and find out if your query has been asked before. Questions have been grouped into simple categories.

1. What is the purpose of the bearing retainer and what benefits accompany different retainer materials?
Ans:The retainer (also called cage or separator) is used to separate the balls and equally position them around the bearing raceway. Some retainer materials contain lubricant for extended bearing life. Retainers for ball bearings are generally available in two designs. The most universal is a 2-piece closed ball pocket design called a ribbon retainer. A single piece open ball pocket design is called a crown retainer. Crown retainers are available in a variety of metal and nonmetal options. PACAMOR KUBAR BEARINGS offers 440C steel retainers in both crown and ribbon designs and plastic crown retainers in either Phenolic or Torlon (polyamide-imide) materials. Phenolic and Torlon retainers are excellent options for high-speed applications. Torlon offers additional bearing life under steam autoclave conditions but requires regular lubrication at maintenance intervals. Phenolic is very forgiving under lube starved and low maintenance environments.

2. Is selecting the right lubricant vital? It seems that bearings fail for other reasons- not from picking the wrong oil or grease?
Ans:Bearings do fail for many reasons, but improper lubrication is there at the top of the list. And the rest are the following:

43% due to improper lubrication;
27% due to improper mounting;
21 % due to other causes and
9% due to reaching the fatigue limit of the metal.

Reasons for lubrication failure are following:
1) Incorrect selection of the grease base for a particular application.
2) Use of static or circulating oil in a improper manner.
3) Insufficient lubrication either in quantity or in required viscosity.
4) Deterioration of prolonged service without proper intervals.
5) Contamination of the lubricant and the bearing with foreign materials.

3. Is there any right or wrong way to store bearings ? Can we put them on a shelf until we need them.
Ans:Yes, there is a right and wrong way to store bearings. You should store bearings in a clean and dry place.. Always use the oldest bearing first. Bearings are precision components and should be treated gently. Never drop them or handle them roughly. In fact, the less you handle them the better since finger prints can lead to rusting. It is necessary to measure temperature changes in your bearing storage area regularly because condition like condensed moisture forms could be harmful for bearings.

4.What is the purpose of bearing lubrication?
Ans: Bearing lubrication is an essential element of bearing selection, as it:
1).Extends fatigue life of the bearing by reducing wear and friction between the mating components of the bearing assembly.
2).Prevents corrosion and extends shelf life.
3).Provides a level of protection from foreign material entering the rolling elements.
4).Reduces the noise level of the bearing, lowers torque, and assists the bearing in reaching maximum operating speed.

5. I do not see a design to fit my application in your catalog. Can you help me design a custom bearing?
Ans: Yes, technical expertise is available to assist with design engineering for custom products. Available options include, but are not limited to, custom rings, retainers, balls, shields, lubricants, and packaging. We look forward to working with you to satisfy your rotary motion requirements.

6. What factors increase or decrease bearing torque?
Ans: Factors that increase bearing torque include:
        1).Increased number of balls in the bearing
        2).Tight crimp ribbon retainer
        3).Tight radial play
        4).High lubricant viscosity
        5).High lube fill in the bearing
        6).High applied bearing load

Factors that decrease bearing torque include:
       1).Fewer balls in the bearing
       2).Crown type or loose crimp retainer
       3).Loose radial play
       4).Low lubricant viscosity
       5).Low lube fill in the bearing
       6).Low applied bearing load

7. What causes bearing noise?
Ans: Bearing noise is a function of both the bearing and the way it is used. Bearing noise is not generally influenced by ABEC and there is no fixed standard among bearing manufacturers for acoustic noise. Some external factors which affect bearing noise include, lubricant type, excessive bearing load, and improper installation.

8. What are ABEC and ISO standards?
Ans: The Annular Bearing Engineers Committee (ABEC) of the American Bearing Manufacturers Association (ABMA) establishes standards for manufacturing precision ball bearings. These standards are also accepted by (ANSI) American Standardization Institute and by international agreement for the standards developed by the International Standards Organization (ISO). The ABEC and ISO bearing standards primarily define tolerances for the ball bearing rings. These standards do not define many other aspects of the bearing such as lube, radial play, ball complement, retainer type, torque, cleanliness, etc.

9. Do your domestic brands come in original boxes?
Yes in most cases. We can also ship them in bulk

10.What about slewing bearing's features?

Major features
Structure compacted tightly and weight light , It has highest static load capacity, also can simultaneously withstand the axial force, radial force and tilting moment.

Rotary transfer machines, welding manipulator, small and medium-sized cranes and excavating machinery, etc.

The normal working temperature of the slewing ring ranges from -25 up to +70°C. Lower or higher temperature are possible but requrie special design provisions by our Engineering Department.

In case when the working environments is particulary aggressive:
Sea atmosphere;
Dust or abrasive environments(sand,coal….);

Particular protection devices must be incorporated such as:

Preventive maintenance operations will be increased to ensure normal operation.

If the slewing rings are continously sollicited by shocks and/or vibrations,the customers must mention it in the specifications in order to design the right piece.

The slewing rings can work whehter by oscillation motion or continous motion.It is necessary to check that the circumferential raceway speed remains within the acceptable limits of respective bearing's capacity.


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