1

A REPORT

ON

INDUSTRIAL TRAINING

done by

Name of student – mukesh kumar

College ID - 10ME030

At

Name of company - National Engineering Industries Ltd. (NEI),

Address - Khatipura Road,Jaipur -302 006 Phone : 2223221 Fax : 0141-2221926.2222259

E-mail : neisales@nbcbearings.i

Submitted to :-

Department of Mechanical Engineering

Anand International College of Engineering

Jaipur-303012

(Approved to AICTE, New Delhi and Affilated to Rajasthan Technical University, Kota)

June/July 2014

.

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CERTIFICATE

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BONAFIDE CERTIFICATE

Certified that this industrial training is a work of mukesh kumar, Anand International College

of Engineering ID-10EDAME030 who carried out the INDUSTRIAL TRAINING at

National Engineering Industries Ltd. (NEI),. Khatipura Road, Jaipur-302006

Co-ordinator

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PREFACE

As per the requirement of B. Tech. Course, National Engineering Industries Ltd. (NEI),

Jaipur has been kind enough to permit me to complete my Practical Training under

BEARING Division.

This report prepared during the practical training which is student’s first and greatest treasure

as it is full of experience, observation and knowledge.

The summer training was very interesting and gainful as it is close to real what have been

studied is all the years through was seen implemented in a modified and practical form.

The student wishes that this Gorgeous Private Sector undertaking success so that it may

flourish and serve the nation which has reached significant years of its independence and has

to achieve many goals.

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ACKNOWLEDGEMENT

Words fail me to express my sincerest gratitude to this esteemed organization, which has

conferred on us the privilege to pragmatically convert our theoretical knowledge into

practical viable experience. During the course of my training at NATIONAL

ENGINEERING INDUSTRIES LIMITED, JAIPUR so many people have guided me and I

will remain indebted to them throughout my life for making my training at NBC, a wonderful

learning experience.

I would like to thank MR. PAWAN NAMA my project head, Mr. RAKESH

OSWAL(HOD), who gave me opportunity to work in his department and guided me through

my project from time to time. His words were a true inspiration for me. The exposure to the

working of the industry that I have got here would not have been possible without his kind

support.

He took keen interest in my project and ensured that my tenure at NBC, JAIPUR is a learning

experience for a lifetime for me.

Thanks to all those operators, Diploma Engineer Trainees and my trainee colleagues with

whom I had developed a special bond. In the end I would like to thank Mr. A. THOMAS for

providing me the opportunity to add a new dimension in my knowledge by getting trained in

this esteemed organization.

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CONTENTS

Chapter No. Topic Page No.

1. DEFINITION OF INDUSTRY 7

2. INTRODUCTION OF NEI 8

3. INTRODUCTION OF BEARING 8

4. INTRODUCTION OF BALL BEARING 11

5. MANUFACTURING PROCESS OF BALL BEARING

a. Inner track wheel

b. Outer track wheel

c. Cage

d. Balls

e. Rivets

6. TROUBLE SHOOTING 31

7. CONCLUSION 33

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DEFINITION OF INDUSTRY

Industry can be defined as:

‘’Any type of Economic Activity producing GOODs or SERVICES‛’

‘‘It is part of a chain – from raw materials to finished product, finished product to

service sector, and service sector to research and development.‛’

‘‘It includes AGRICULTURE, MANUFACTURING and SERVICES‛’

‘‘Industry varies over time and between different countries‛’

Industrial linkage:

‘‘When one Industry depends on the output of another‛’

This can cause problems if one industry has production problems or closes down

The CAR INDUSTRY is a good example – each component (engine parts, lights, body etc.)

may be produced by a different company before it goes to the ASSEMBLY PLANT.

BEARING INDUSTRY GLOBAL SCENERIO :

The world Market of quality Bearing is very vast. The Big players of bearing sector are

present in U.S.A, Russia, Japan, China and Eastern Europe. Some of leading bearing

Manufacturers are: -

- NSK Japan

- NTN Japan

- KOYA Seiko Japan

- FAG Germany

- SKF Sweden

- NRB France

- Timken USA

There are few of leading bearing manufacturer present in India. Most of the big player is

having either technical or financial Collaboration with leading Auto Manufacturer.

International Collaboration gives Access to best technology in the world.

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BEARING INDUSTRY INDIAN SCENERIO:

The Indian Bearing Industry is estimated at Rs. 30 Billion Approximately. The Industry has

established a highly diversified product range of around 1000 type of Bearing having High

Volume Demand. As much as 70% of the total

Demand for common varieties and size of bearing is met by the domestic Industry, and the

remaining demand to the tune of 30% is imported essentially for Industrial Application and

special purpose.

The Indian bearing Industry can be divided in to the organized sector and un-organized

sector. The organized sector primarily caters to the original equipment Manufacturer (OEM)

Segment, which predominantly comprises automotive industries and other mechanical

Industrial users. The replacement market is dominated by unorganized Sector.

ABOUT NEI:

Bearing in India started with the setting up of manufacturing unit in JAIPUR by the Birla

Group in 1946 under the name of "National Bearing Company Ltd."

The 1st Bearing was manufactured in 1950 with a modest start of 30 thousand bearing in 19

Sizes. The Bearing Races (Soft) was Manufactured by the Tiny Unit in the Small Scale

Sector at Jaipur during 1970 on Job Work basis.

It is a view to utilize the end piece of the Stainless steel tube which could not be fed to the

Multi operation of National Engineering Industries Jaipur.

There after there is a continuous growth of this Industry and now it has grown to a level that

Almost All the Leading Manufacturer of the country are procuring Soft Bearing Races from

JAIPUR. The National Engineering Industries procure lakhs of Ring every month from these

Bearing Race Manufacturing Unit.

The other leading manufacturer like S.K.F., FAG, TATA Bearing, NBC are also procuring

the Bearing races from Jaipur. In addition to above, the Small Scale Units manufacturing

Bearing in the state of Rajasthan, Delhi, Gujarat and Punjab also purchasing Bearing Races

and components from Jaipur.

BEARING:-

A bearing is a device to allow constrained relative motion between two or more parts,

typically rotation or linear movement.

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Bearings may be classified broadly according to the motions they allow and according to

their principle of operation as well as by the directions of applied loads they can handle.

TYPES:-

There are many different types of bearings.

Type Description Friction Stiffness

† Speed Life Notes

Plain

bearing

Rubbing surfaces,

usually with lubricant; some

bearings use pumped lubrication and

behave similarly to

fluid bearings.

Depends on materials and

construction, PTFE has

coefficient of friction ~0.05-0.35,

depending upon fillers

added

Good,

provided wear is

low, but some slack is

normally present

Low to

very high

Low to very

high - depends upon application and lubrication

Widely used, relatively

high friction, suffers from stiction in

some applications.

Depending upon the application,

lifetime can be higher or

lower than rolling element

bearings.

Rolling

element

bearing

Ball or rollers

are used to prevent or

Rolling

coefficient of friction with

Good,

but some slack is

Moderat

e to high (often

Moderate to

high (depends on lubrication,

Used for

higher moment

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minimize

rubbing

steel can be

~0.005 (adding

resistance due to seals, packed

grease, preload and

misalignment can increase

friction to as much as

0.125)

usually

present

requires

cooling)

often requires

maintenance)

loads than

plain bearings with

lower friction

Jewel

bearing

Off-center

bearing rolls in seating

Low Low due to flexing

Low

Adequate

(requires maintenance)

Mainly used

in low-load, high precision

work such as clocks. Jewel

bearings may be very small.

Fluid

bearing

Fluid is forced

between two faces and held in by edge seal

Zero friction

at zero speed, low

Very high

Very high

(usually limited

to a few hundred feet per

second at/by

seal)

Virtually infinite

in some applications,

may wear at startup/shutdown in some cases.

Often negligible maintenance.

Can fail

quickly due to grit or dust or other

contaminants.

Maintenance free in continuous

use. Can handle very

large loads with low friction.

Magneti

c

bearings

Faces of bearing are

kept separate by magnets

(electromagnets or eddy currents)

Zero friction at zero

speed, but constant

power for levitation, eddy

currents are often

induced when movement

Low No practical

limit

Indefinite. Maintenance free. (with

electromagnets)

Active magnetic

bearings (AMB) need

considerable power. Electro

dynamic bearings

(EDB) do not require external

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occurs, but

may be negligible if

magnetic field is quasi-static

power.

Flexure

bearing

Material flexes to give and

constrain movement

Very low Low Very

high.

Very high or low depending

on materials and strain in

application. Usually maintenance

free.

Limited

range of movement, no backlash,

extremely smooth

motion

†Stiffness is the amount that the gap varies when the load on the bearing changes, it is distinct from the friction of the bearing.

Table 1: Types of bearing

INTRODUCTION OF BALL BEARING

A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation

between the bearing races.

The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads.

It achieves this by using at least two races to contain the balls and transmit the loads through

the balls. In most applications, one race is stationary and the other is attached to the rotating

assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate

as well. Because the balls are rolling they have a much lower coefficient of friction than if two

flat surfaces were sliding against each other.

Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element

bearings due to the smaller contact area between the balls and races. However, they can

tolerate some misalignment of the inner and outer races.

COMMON DESIGNS

There are several common designs of ball bearing, each offering various trade-offs. They can

be made from many different materials, including: stainless steel, chrome steel,

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and ceramic(silicon nitride (Si3N4)). A hybrid ball bearing is a bearing with ceramic balls and

races of metal.

ANGULAR CONTACT

An angular contact ball bearing uses axially asymmetric races. An axial load passes in a

straight line through the bearing, whereas a radial load takes an oblique path that tends to

want to separate the races axially. So the angle of contact on the inner race is the same as that

on the outer race. Angular contact bearings better support "combined loads" (loading in both

the radial and axial directions) and the contact angle of the bearing should be matched to the

relative proportions of each. The larger the contact angle (typically in the range 10 to 45

degrees), the higher the axial load supported, but the lower the radial load. In high speed

applications, such as turbines, jet engines, and dentistry equipment, the centrifugal forces

generated by the balls changes the contact angle at the inner and outer race. Ceramics such

as silicon nitride are now regularly used in such applications due to their low density (40% of

steel). These materials significantly reduce centrifugal force and function well in high

temperature environments. They also tend to wear in a similar way to bearing steel—rather

than cracking or shattering like glass or porcelain.

Most bicycles use angular-contact bearings in the headsets because the forces on these

bearings are in both the radial and axial direction.

AXIAL

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An axial ball bearing uses side-by-side races. An axial load is transmitted directly through the

bearing, while a radial load is poorly supported and tends to separate the races,so that a larger

radial load is likely to damage the bearing.

DEEP-GROOVE

In a deep-groove radial bearing, the race dimensions are close to the dimensions of the balls

that run in it. Deep-groove bearings can support higher loads.

CONSTRUCTION TYPES

CONARD

The Conrad-style ball bearing is named after its inventor, Robert Conrad, who was awarded

British patent 12,206 in 1903 and U.S. patent 822,723 in 1906. These bearings are assembled

by placing the inner race into an eccentric position relative to the outer race, with the two

races in contact at one point, resulting in a large gap opposite the point of contact. The balls

are inserted through the gap and then evenly distributed around the bearing assembly, causing

the races to become concentric. Assembly is completed by fitting a cage to the balls to

maintain their positions relative to each other. Without the cage, the balls would eventually

drift out of position during operation, causing the bearing to fail. The cage carries no load and

serves only to maintain ball position.

Conrad bearings have the advantage that they are able to withstand both radial and axial

loads, but have the disadvantage of lower load capacity due to the limited number of balls

that can be loaded into the bearing assembly. Probably the most familiar industrial ball

bearing is the deep-groove Conrad style. The bearing is used in most of the mechanical

industries.

SLOT-FILL

In a slot-fill radial bearing, also referred to as a full complement design, the inner and outer

races are notched on one face so that when the notches are aligned, balls can be slipped in the

resulting slot to assemble the bearing. A slot-fill bearing has the advantage that the entire

groove is filled with balls, called a full complement, resulting in a higher radial load capacity

than a Conrad bearing of the same dimensions and material type. However, a slot-fill bearing

cannot carry a significant axial load on the loading slot side. Also, the slots cause a

discontinuity in the races that has a small but adverse effect on strength.

ROWS

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There are two row designs: single-row bearings and double-row bearings. Most ball bearings

are a single-row design, which means there is one row of bearing balls. This design works

with radial and thrust loads. A double-row design has two rows of bearing balls. Their

disadvantage is they need better alignment than single-row bearings.

FLANGED

Bearings with a flange on the outer ring simplify axial location. The housing for such

bearings can consist of a through-hole of uniform diameter, but the entry face of the housing

(which may be either the outer or inner face) must be machined truly normal to the hole axis.

However such flanges are very expensive to manufacture. A more cost effective arrangement

of the bearing outer ring, with similar benefits, is a snap ring groove at either or both ends of

the outside diameter. The snap ring assumes the function of a flange.

CAGED

Cages are typically used to secure the balls in a Conrad-style ball bearing. In other

construction types they may decrease the number of balls depending on the specific cage

shape, and thus reduce the load capacity. Without cages the tangential position is stabilized

by sliding of two convex surfaces on each other. With a cage the tangential position is

stabilized by a sliding of a convex surface in a matched concave surface, which avoids dents

in the balls and has lower friction. Caged roller bearings were invented by John Harrison in

the mid-18th century as part of his work on chronographs. Caged bearings were used more

frequently during wartime steel shortages for bicycle wheel bearings married to replaceable

cups.

CERAMIC HYBRID BALL BEARINGS USING CERAMIC BALLS

Ceramic bearing balls can weigh up to 40% less than steel ones, depending on size and

material. This reduces centrifugal loading and skidding, so hybrid ceramic bearings can

operate 20% to 40% faster than conventional bearings. This means that the outer race groove

exerts less force inward against the ball as the bearing spins. This reduction in force reduces

the friction and rolling resistance. The lighter balls allows the bearing to spin faster, and uses

less energy to maintain its speed. While ceramic hybrid bearings use ceramic balls in place of

steel ones, they are constructed with steel inner and outer rings; hence the hybrid designation.

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SELF-ALIGNING

Self-aligning ball bearings, such as the Wingquist bearing, are constructed with the inner ring

and ball assembly contained within an outer ring that has a spherical raceway. This

construction allows the bearing to tolerate a small angular misalignment resulting from

deflection or improper mounting.

OPERATING CONDITION

LIFESPAN

The calculated life for a bearing is based on the load it carries and its operating speed. The

industry standard usable bearing lifespan is inversely proportional to the bearing load cubed.

Nominal maximum load of a bearing (as specified for example in SKF datasheets), is for a

lifespan of 1 million rotations, which at 50 Hz (i.e., 3000 RPM) is a lifespan of 5.5 working

hours. 90% of bearings of that type have at least that lifespan, and 50% of bearings have a

lifespan at least 5 times as long.

The industry standard life calculation is based upon the work of Lundberg and Palmgren

performed in 1947. The formula assumes the life to be limited by metal fatigue and that the

life distribution can be described by a Weibull distribution. Many variations of the formula

exist that include factors for material properties, lubrication, and loading. Factoring for

loading may be viewed as a tacit admission that modern materials demonstrate a different

relationship between load and life than Lundberg and Palmgren determined.

FAILURE MODES

If a bearing is not rotating, maximum load is determined by force that causes plastic

deformation of elements or raceways. The identations caused by the elements can concentrate

stresses and generate cracks at the components. Maximum load for not or very slowly

rotating bearings is called "static" maximum load. For a rotating bearing, the dynamic load

capacity indicates the load to which the bearing endures 1.000.000 cycles.

If a bearing is rotating, but experiences heavy load that lasts shorter than one revolution,

static max load must be used in computations, since the bearing does not rotate during the

maximum load.

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Maximum load

In general, maximum load on a ball bearing is proportional to outer diameter of the bearing

times width of bearing (where width is measured in direction of axle).

Lubrication

For a bearing to operate properly, it needs to be lubricated. In most cases the lubricant is

based on elastohydrodynamic effect (by oil or grease) but working at extreme temperatures dry

lubricated bearings are also available.

For a bearing to have its nominal lifespan at its nominal maximum load, it must be lubricated

with a lubricant (oil or grease) that has at least the minimum dynamic viscosity (usually

denoted with the Greek letter ) recommended for that bearing. The recommended dynamic

viscosity is inversely proportional to diameter of bearing. The recommended dynamic

viscosity decreases with rotating frequency. As a rough indication: for less than 3000 RPM,

recommended viscosity increases with factor 6 for a factor 10 decrease in speed, and for more

than 3000 RPM, recommended viscosity decreases with factor 3 for a factor 10 increase in

speed.

For a bearing where average of outer diameter of bearing and diameter of axle hole is 50 mm,

and that is rotating at 3000 RPM, recommended dynamic viscosity is 12 mm²/s. Note that

dynamic viscosity of oil varies strongly with temperature: a temperature increase of 50–70

°C causes the viscosity to decrease by factor 10.

If the viscosity of lubricant is higher than recommended, lifespan of bearing increases,

roughly proportional to square root of viscosity. If the viscosity of the lubricant is lower than

recommended, the lifespan of the bearing decreases , and by how much depends on which

type of oil being used. For oils with EP ('extreme pressure') additives, the lifespan is

proportional to the square root of dynamic viscosity, just as it was for too high viscosity,

while for ordinary oil's lifespan is proportional to the square of the viscosity if a lower-than-

recommended viscosity is used.

Lubrication can be done with a grease, which has advantages that grease is normally held

within the bearing releasing the lubricant oil as it is compressed by the balls. It provides a

protective barrier for the bearing metal from the environment, but has disadvantages that this

grease must be replaced periodically, and maximum load of bearing decreases (because if

bearing gets too warm, grease melts and runs out of bearing). Time between grease

replacements decreases very strongly with diameter of bearing: for a 40 mm bearing, grease

should be replaced every 5000 working hours, while for a 100 mm bearing it should be

replaced every 500 working hours. Lubrication can also be done with an oil, which has

advantage of higher maximum load, but needs some way to keep oil in bearing, as it normally

tends to run out of it. oil quality; therefore, the oil is usually changed less frequently than the

oil in bearings.

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DIRECTION OF LOAD

Most bearings are meant for supporting loads perpendicular to axle ("radial loads").

Whether they can also bear axial loads, and if so, how much, depends on the type of

bearing. Thrust bearings (commonly found on lazy susans) are specifically designed for axial

loads.

For single-row deep-groove ball bearings, SKF's documentation says that maximum axial

load is circa 50% of maximum radial load, but it also says that "light" and/or "small" bearings

can take axial loads that are 25% of maximum radial load.

For single-row edge-contact ball bearings, axial load can be circa 2 times max radial load,

and for cone-bearings maximum axial load is between 1 and 2 times maximum radial load.

If both axial and radial loads are present, they can be added vectorially, to result in total load

on bearing, which in combination with nominal maximum load can be used to predict

lifespan. However, in order to correctly predict the rating life of ball bearings the ISO/TS

16281 should be used with the help of a calculation software.

AVOIDING UNDESIRABLE AXIAL LOAD

The part of a bearing that rotates (either axle hole or outer circumference) must be fixed,

while for a part that does not rotate this is not necessary (so it can be allowed to slide). If a

bearing is loaded axially, both sides must be fixed.

If an axle has two bearings, and temperature varies, axle shrinks or expands, therefore it is

not admissible for both bearings to be fixed on both their sides, since expansion of axle

would exert axial forces that would destroy these bearings. Therefore, at least one of bearings

must be able to slide.

A 'freely sliding fit' is one where there is at least a 4 µm clearance, presumably because

surface-roughness of a surface made on a lathe is normally between 1.6 and 3.2 µm.

FIT

Bearings can withstand their maximum load only if the mating parts are properly sized.

Bearing manufacturers supply tolerances for the fit of the shaft and the housing so that this

can be achieved. The material and hardness may also be specified.

Fittings that are not allowed to slip are made to diameters that prevent slipping and

consequently the mating surfaces cannot be brought into position without force. For a bearing

to have its nominal lifespan at its nominal maximum load, it must be lubricated with a

lubricant (oil or grease) that has at least the minimum dynamic viscosity (usually denoted

with the Greek letter ) recommended for that bearing.

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MANUFACTURING OF BALL BEARING

Ball bearings are at the heart of almost every product with a rotating shaft .Most bearing

specifications and manufacturing tolerances are quantified in one-ten thousandths of an

inch (1/10,000) by ABMA; every manufacturing process is 100% checked and feedback

provided to ensure the integrity of the process and product.

Note: A micron (an abbreviation for micrometers) is one-millionth of a meter, or,

25,400 microns equals one (1) inch.

REPEATABILITY IN THE MANUFACTURING PROCESS

Predictable uniformity, or repeatability, in the manufacturing process is crucial to ensuring

consistent bearing performance. If variations occur in the manufacturing process from part

to part, the production line may make bearings that fall within the complete spectrum of

the allowable tolerance standards. That inconsistency-- producing parts that go from one

end of the range to the other--can lead in turn to variations in the performance of each

bearing, either individually or from lot to lot. The narrower the variation in each step of

the manufacturing process, the greater the consistency of each

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Manufacturing Flow Chart

Forged Rings (De-scaled) as Raw Material.

(SAE 52100 steel)

Turning Operation

Center Less Grinding

Heat Treatment

Hardness testing

Rough Grinding

Finish Grinding

Honing & Super Finishing

Washing

Application of rust preventive

Ready for dispatch to assembly

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Ball Bearing Materials

Ball bearings are generally made of high carbon steels, such as AISI 52100(fifty-two,

one hundred). One of the factors that determine the life of the bearing steel (thus the

bearing itself) is the purity or cleanliness of the steel. The 52100 steel are subjected to a

rigorous purification process with stringent controls in order to meet the ever-increasing

standards for cleanliness–eliminating nonmetallic inclusions or impurities. These

impurities are removed through various processes such as vacuum degassing and

consumable-electrode vacuum melting (CEVM), to name just two of the processes referred

to when discussing the merits and cleanliness of bearing steel.

The hardening of the steel is achieved by a heat treating process in which the steel microstructure is manipulated by cycles of heating and quick cooling to obtain the optimum hardness range for the steel–usually on the order of 60to 64 on the

Rockwell C Hardness scale. Penetration hardness tests (such as Rockwell or Brinell ) provide the means to estimate the actual hardness of metals.

Raw Material for bearings Races:

For Outer and inners the suggested raw material is SAE 52100 conforming to following

chemical

compositions Element C Si Mn S P Cr.

Minimum .98 .15 .25 -- -- 1.30

Maximum 1.10 .35 .45 0.025 0.025 1.60

Oxygen content; Not More than 15 ppm

Micro Inclusions

Inclusion type Series

Thin Thick

(A) Sulphides 2.5 1.5

(B) Alumina 2.0 1.0

(C) Silicate 0.5 0.5

(D) Globular Oxide 1.0 1.0

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TURNING SECTION

Both the inner and outer rings are usually machined from the outer and Inner races are

manufactured from SAE 52100 steel, the raw material used in the section has been

considered as forged rings.

The turning operations are divided into various lathe operations, viz. O.D., face, track

and Bore. All these operations are done on production lathe machines. These lathe

machines offered in the project are production machines wherein individual job/

process sequence has to be set before every new batch is taken up.

HEAT TREATMENT

Hardness is a function of and brittle structure. When slowly quenched it would form

Austenite and Pearlite which is a partly hard and partly soft structure. When the

cooling rate is the Carbon content of the steel. Hardening of steel requires a change

in structure from the body-centered cubic structure found at room temperature to the

face-centered cubic structure found in the Austenitic region. The steel is heated to

Austenitic region. When suddenly quenched, the Martensite is formed. This is a

verystrong extremely slow then it would be mostly Pearlite, which is extremely soft.

The soft machined material is feed in the furnace and washed at 600 C, then send to a

chamber where the material heated in four chambers the first chamber has the temperature

8400 C and further chamber contains the 8500 C temperature.

Then it dipped into an oil tank at temperature 250C where the material get quenched then it

washed and then it tempered in water about 90 min. at temperature 1050 C .

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QUENCHING MEDIA

Quenching is the act of rapidly cooling the hot steel to harden the steel.

Oil:

Oil is used when a slower cooling rate is desired. Since oil has a very high boiling

point, the transition from start of Martensite formation to the finish is slow and this

reduces the likelihood of cracking. Oil quenching results in fumes, spills and sometimes

a fire hazard Austenite at room temperature.

Different alloys. The reason to alloy steels is not to

increase their strength, but increase their harden ability – the ease with which full

hardness can be achieved throughout the material. Usually when hot steel is quenched, most

of the cooling happens at the surface, as does the hardening. The propagates into the depth of

the material. Alloying helps in the hardening and by determining the right alloys one can

achieve the desired properties for the particular application. Such alloying also helps in

reducing the need for a rapid quench cooling – thereby eliminate distortions and potential

cracking. In addition, thick sections can be hardened fully.

Quenches are usually done to room temperature. Most medium carbon steels and low alloy

steels undergo transformation to 100% Martensite at room temperature. However, high

carbon and high alloy steels have retained To eliminate retained Austenite, the quench

temperature has to be lowered. This is the reason to use cryogenic quenching.

NITROGEN METHANOL SYSTEM

The above system comprise of Methanol Tank 200 liters SS 2.5 mm corrugated, Methanol

Flow Meter 0.50 to 5.2 per hour, Solenoid Valve, Needle Valves, all interconnected by

copper piping duly mounted on a stand with Nitrogen Pressure Regulator and Flow meter to

read 2 to 5 m3/hr.

GRINDING SECTION

The next stage is grinding, in order to give the rings the right form and dimensions.

The first operation on inner and outer rings is face grinding. Both faces are ground

simultaneously to give the final width.

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Face is the surface at side of the inner and outer race , face should be finished indeed to get

the desire width of the bearing and since the bearing is a mating part and it has to be

assembled somewhere in the machine where it should be fit precisely.

Manufacturing Process of ball bearing

Input Wire Rod as Raw Material.

(SAE 52100 Steel)

Shearing & Heading operation

On Ball Header Machine

Deburring on Vibro Benz Machine

Flushing of excess material after the

Ball forged in cold header

Heat treatment of ball

Lapping in Ball Lapping machine

Inspection for checking

Hairline cracks

Lapping of balls in

Tumbling barrel

Magnetic Crack Testing and

Washing

Application of rust preventive and

Packing

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The raw material used in the manufacture of balls is a specially formulated grade of

steel ring around the to remove this ring. wire. The raw material is supplied from either

wire or rod. It is then cut to length and the width is a small percentage larger than the

width of the finished ball. The wire or rod is then fed through a header. This cold

forged process produces "slugs" at an incredibly high speed. Wire is fed from decoilers

into cold heading machines where it is cut into blanks then pressed into between

hemispherical dies, The flash around the balls produced during pressing is removed

by filing plates in deburring machines.

Heat Treating Balls

Ball Flashing Operation

.

The balls are then machined in rill-filing machines, equipped with one fixed and one

rotating cast iron rill-plate. Concentric grooves in the plates ensure that the whole

ball surface is machined to the same extent and thus a spherical form is achieved.

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Final inspection for size, form and surface finish is carried out on a samplebasis by

means of microscopes and other precision equipment. The balls are then cleaned and

packed ready for bearing assembly operations. The tiniest deviation in the roundness

of bearing elements can have an impact on bearing quality. Periodic form deviations

in the range of 1angstrom 10-10 m may influence bearing quality.

CAGE MANUFACTURING

Flow chart

Raw material (narrow width CR sheet)

Blanking and punching

Forming (pocketing)

Inspection and batch checking

Shot blasting virbro

Assembly in assy. shop

The cages for various bearings sizes are manufactured from Cold Rolled narrow width

sheets IS 4397 cold rolled, cold annealed sheets, and The CR sheet is converted in the

cage in Press machines in successive press operations:

Blanking, Punching, forming (pocketing) rivet holes and visual inspection is carried for any

deformity. Cages are manufactured from cold rolled steel strip. Presses with progressiveor,

alternatively, transfer tools are used to produce cages halves from the strip. After surface

treatment and cleaning, the cage halves are coated with preservative and packed for

transport to the assembly plant.

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RIVET MANUFACTURING

Flow chart

Raw material

(wire EN 8)

Heading in ball header

Deburring in vibrobenz machine

Rust preventive oiling

Ready for assembly

The rivets are manufactured from wire rods, the wires is cut in required size in rivet

header machines, then in the vibro machines it is super finished. There is no grinding

operation involved.

PROCESS OF MAKING A BEARING

27

FLOW CHART

Cage Rivet Outer Inner Balls

Put inner in outer

Insert balls

put under riveting machine

riveting

Washing of bearing

Demegnetizing

Clearance testing

Packaging of bearing in pillow wrapping machine

Ready to dispatch

28

Finally the rings, balls and cage - which have been manufactured in different locations -

come together for automatic assembly. Raceway diameters of inner and outer rings are

measured separately. By selecting suitable combinations of ring and ball sizes, the

required internal clearance is obtained. Balls are fed between the rings and spaced

equally before the two cage halves are fitted and then riveted together.

Prior to automatic assembly the rings are optically inspected. After washing, the final

inspection sequence starts. This consists of a number of automated stations, which check

running accuracy, vibration level, and outside and bore diameters, as well as radial

clearance of the bearings. The bearings are then automatically washed, coated with

preservative, greased and fitted with seals or shields, before being packed according to

customer requirements.

29

Materials

Material comparison for common bearing balls ]

Material UNS

52100

Stainle

ss

steel

440C

M50 BG-42 REX-

20

440ND

UR

Hayne

s 25 Si3N4 BECU 455 C276

Hardness

[HRC] 60 58 62 62 66 60 50 70 40 50 40

Temperat

ure limit

[°F]

300 300 400 400 600 300 1200 1500 400 500 1000

Corrosion

resistanc

e

1 3 1 2 1 4 5 5 1 4 5

Cost 1 1 1 2 3 1 5 5 3 2 4

Availabili

ty 1 1 2 2 2 4 5 3 3 2 4

Magnetic Magne

tic

Magne

tic

Magne

tic

Magne

tic

Magne

tic

Magne

tic

Non-

magne

tic

Non-

magne

tic

Non-

magne

tic

Magne

tic

Magne

tic

Size limit None None None None None None

1.5 in

(38 m

m)

No

Torqu

e Tube

None None

5 in

(130 m

m)

Relative

load 3 2 4 4 5 3 1 5 1 1 1

30

Bearing Visual Defects:

Appearance Cause Action Photo

Small indentations

around the

raceways and

rolling elements.

Dull, worn

surfaces.

Lack of

cleanliness

before and

during mounting

operation.

Do not unpack

bearing until just

before it is to be

mounted. Keep

workshop clean

and use clean

tools.

Outer ring of a spherical

roller bearing with

raceways that have been

worn by abrasive

particles. It is easy to

feel where the dividing

line goes between worn

and unworn sections.

Grease discoloured

green.

Ineffective seals Check and

possibly improve

the sealing.

Lubricant

contaminated by

worn particles

from brass cage

Always use fresh,

clean lubricant.

Wipe the grease

nipples. Filter the

oil.

Appearance Cause Action Photo

Worn, frequently

mirror-like, surfaces;

at a later stage blue

to brown

discoloration.

Lubrication has

gradually been

used up or has

lost its lubricating

properties.

Check that the

lubricant reaches

the bearing.

More frequent

relubrication.

Outer ring of a

spherical roller bearing

that has not been

adequately lubricated.

The raceways have a

mirror finish.

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Appearance Cause Action Photo

Depressions in raceways.

These depressions are

rectangular in roller bearings

and circular in ball bearings.

The bottom of these

depressions may be bright or

dull and oxidized.

The bearing

has been

exposed to

vibration while

stationary.

Secure the

bearing during

transport by

radial

preloading.

Provide a

vibration-

damping base.

Where possible,

use ball

bearings

instead of roller

bearings.

Employ oil bath

lubrication,

where possible.

Outer ring of taper

roller bearing

damaged by

vibration during

operation.

Vibration damage to

the ring of a

cylindrical roller

bearing. The damage

has arisen while the

bearing was not

running.

Inner and outer ring

of a cylindrical roller

bearing exposed to

vibration. The inner

ring has changed

position.

32

CONCLUSION

My training at NATIONAL ENGINEERING INDUSTRIES, JAIPUR was very fruitful and I

gained a lot of practical knowledge about various manufacturing processes and techniques. I

also got the opportunity to realize the challenges faced and expertise required in

manufacturing processes for mass production.

It was indeed a great experience undergoing training at the plant.

33