TRIBOLOGY

Rolling Element Bearing

Contents

Introduction4

Rolling Element Bearing5

Ball Bearing5

Design5

Types of Ball Bearings6

Ball Bearing with Shafts6

Ball bearings without Shafts7

Thrust Ball Bearings7

Angular Contact Bearing7

Radial Ball Bearing7

Roller Bearing8

Basic Design8

Types of Rolling Bearing8

Tapered Roller Bearing8

Spherical Roller Bearing9

Cylindrical Roller bearing9

Friction9

Materials used for making Gears10

Surface of the gears13

Lubrication for smoother operation of gears:15

Lubrication in Rolling Element Bearings17

Lubrication Method18

Bearing Failures and their Causes19

Wear19

Smearing20

Corrosion20

Damage by Electric Current21

Applications21

Changes to Improve Performance22

Reference24

Appendices………………………………………………………………………………………………..18

Rolling Element Bearing

Introduction

Tribology is the science of surfaces with relative motion which are interacting with each other. It includes the study of friction, wear and lubricant (Bushan,B, 2000, Pp 1-3). When one body slides over another, a resistive force is created, known as friction. Considering friction as a loss of energy, many attempts are made to eliminate it or reduce it to a small quantity. The frictional force can results in wear of the surfaces. Wear is the removal of the surface when the two surfaces slides over each other. This can result in change in the dimension of the components giving rise to improper results. There are many types of wear encountered by the sliding surfaces. Adhesive wear results when two surfaces slides over each other and friction produced can cause change in the dimension of the surfaces. Abrasive wear results when the hard surfaces slide over the soft surfaces. Erosive wear occurs when the particles of solid or liquid slides over the surface. The common example is the movement of slurries through pumping equipment.

The study of Tribology is commonly use in designing of the bearings. A Bearing is an element which restricts the motion between the moving parts to only the desired motion. The purpose of this is to reduce the wear of the surfaces in contact during the motion. Rolling element bearings are the most common type of bearing widely used nowadays. These bearings reduce friction by carrying a rolling element such as ball or roller between the rings (Alexander Solcum, 2008, Pp 1-2). These bearings have the advantage of low cost, smaller size, accuracy and durability. Tribological component that will be discussed in this assignment is Rolling Element Bearing. This rolling element bearing can further be classified into Ball Bearing and Roller Bearing.

Rolling Element Bearing

Rolling Element Bearing is the most common type of bearing widely used in machines to reduce friction. This type of bearing uses balls or rollers to separate the inner and outer tracks also known as raceways. These are also called antifriction because rolling element bearings have low friction compare to the fluid bearings and sliding contact bearing. Frictional torque in the rolling element bearing is lower than the other types of bearing. The starting friction torque is marginally greater than the operating friction torque. Deflection in this bearing is also less sensitive to the variation of the load. Roller element bearings also require low amount of lubricant for operation. As they are smaller in size compare to the other bearings, they can be use in compact units. The two types of rolling element bearing are Ball Bearing and Roller ...