REPRRESENTED BY AKHILESH KUMAR 14UPE054 PRODUCTION ENGINEERING

CONTENT Introduction Function of Bearing Classification Types and Application Friction Loads Magnitude of load Direction of load Speed 2

INTRODUCTION A Bearing is a device to permit constrained relative motion between two parts, typically rotation or linear movement. When there is a relative motion between two machine parts, one of which supports the others. The supporting member is called Bearing. 4

FUNCTION OF BEARING A bearing permits relative motion between two machine members while minimizing Frictional resistance. A bearing consists of an inner and outer member separated either by a thin film of Lubricant or a rolling element. A bearing bears the load. It locates the moving parts in correct position. It provides free motion to the moving part by reducing friction. 3

CLASIFICATION OF BEARING Bearing are classified depending upon the load. Bearing are also classified depending upon the type of contact. 1. Sliding contact bearing - journal bearing - plane bearing 2. Antifriction bearing - Ball bearing - roller bearing 5

Slider bearing In which the rotating shaft has a sliding contact with the bearing which is held stationary. Due to large contact area friction between mating parts is high requiring greater lubrication. 6

Type of slidding bearing Journal bearing – in this the bearing pressure is exerted at right angles to the axis of the axis of the shaft. The portion of the shaft lying within the bearing in known as journal. shaft are generally made of mild steel. Foot step or pivot bearing – in this bearing the bearing pressure is excreted parallel to the shaft whose axis is vertical. Note that in this case the end of the shaft rests within the bearing. Plane bearing – in this bearing supporting pressure is parallel to the axis of the shaft having end thrust. Thrust bearing are used in bevel mountings, propeller drives, turbines, etc. note here the shaft,unlike foot-strep bearing passes through and beyond the bearing. 7

Rolling or anti-friction bearing Due to less contact area rolling friction is much lesser than the sliding friction, hence these bearings are also known as antifriction bearing. 8

Type of antifriction bearing Ball bearing: Incorporating a deep hardened raceway which makes them suitable for radial and axial loads in either direction, providing the radial loads are greater than the axial loads. Roller bearing: Roller bearing have a greater load-carrying capacity than ball bearing of equivalent size as they make line contact rather than point contact with their rings. Not suitable for axial loading, cheaper to manufacture, used for heavy and sudden loading, high speed and continuous service. 9

Friction Reducing friction in bearings is often important for efficiency, to reduce wear and to facilitate extended use at high speeds and to avoid overheating and premature failure of the bearing. Essentially, a bearing can reduce friction by virtue of its shape, by its material, or by introducing and containing a fluid between surfaces or by separating the surfaces with an electromagnetic field. By shape, gains advantage usually by using spheres or rollers, or by forming flexure bearings.rollers 10

By material, exploits the nature of the bearing material used. (An example would be using plastics that have low surface friction.) By fluid, exploits the low viscosity of a layer of fluid, such as a lubricant or as a pressurized medium to keep the two solid parts from touching, or by reducing the normal force between them. By fields, exploits electromagnetic fields, such as magnetic fields, to keep solid parts from touching. Combinations of these can even be employed within the same bearing. An example of this is where the cage is made of plastic, and it separates the rollers/balls, which reduce friction by their shape and finish. 11

Loads Bearings vary greatly over the size and directions of forces that they can support. Forces can be predominately radial, axial (thrust bearings) or bending moments perpendicular to the main axis. 12

Magnitude of load The magnitude of the load is one of the factors that usually determines the size of the bearing to be used. Generally, roller bearing are available to support heavier loads than similar size ball bearing and bearings having a full compliment of rolling elements can accommodate heavier loads than the corresponding caged bearing. 13

Direction of load Axial load :- The load which comes axis on the shaft called Axial load. Thrust ball bearing and four point contact ball bearing are suitable for light or moderate loads that are purely axial 14

Radial load :- The load which comes perpendicular on the shaft called redial load. Cylindrical roller bearing, needle roller bearing, and toroidal roller bearing can only support pure Radial loads. 15

Combined load :- A combined load comprises a redial and an axial load acting simultaneously For combined loads, single and double row angular contact ball bearing, and single row taper roller bearing are most commonly used, although deep groove ball bearing and spherical roller bearing are suitable. 16

Speed The permissible operating temperature limits the speed at which rolling bearings can be operated. Bearing types with low friction and correspondingly low heat generation inside the bearing are therefore the most suitable for high - speed operation. 17

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