1

CHAPTER-1

INTRODUCTION

1.1. Company profile

The renowned industrialist, late Shree B. M. Birla founded National Engineering

Industries Ltd., Jaipur in the year 1946 as a pioneer industry in the field of bearing

manufacture, under the name of "National Bearing Company Ltd."

The first bearing was manufactured in 1950 with a modest start of 30,000 bearings in

19 sizes. The company is now manufacturing nearly 3.8 million bearings per month in

over 500 different sizes ranging from 6 mm bore to 1300 mm outer diameter and has

the capacity to manufacture bearings upto 2000 mm outer diameter. At NEI, the

development of bearings is a never ending job. With ever increasing activities and

grant of industrial licenses for other vital industries and manufacturing of Roller

Bearing Axle Boxes for Railway Rolling Stock, Steel Balls, Tapered Roller Bearings,

Spindle Inserts etc., the name of the company was changed in 1958 to "National

Engineering Industries Ltd." retaining its original trade mark NBC.

The industry is spread over 118 acres of land in Jaipur and 56 acres in Gunsi (Newai).

This is the only unit in the country manufacturing wide variety and range of bearings

such as Ball Bearings, Steel Balls, Tapered Roller Bearings, Cylindrical Roller

Bearings & Axle Boxes for Railway Rolling Stock including Spherical Roller

Bearings, Cartridge Tapered Roller Bearings and Large Diameter special Bearings in

separate fully equipped factories. The development of National Engineering Industries

Ltd., was pioneered with a theme “Indigenization and Self-reliance".

NBC Bearings are widely used by 2 and 3 Wheelers, Cars, Trucks, Tractors, Electric

Motors, Railway wagon, Coach and Locomotive manufacturers as Original

Equipment and Steel Mills, Heavy Engineering Plants, Bulldozers, Shovels, Tillers

and Thermal Power Plants all across the country.

2

1.2. Milestones

Fig.1.1 Milestones of NEI

i. 1946 -Company established as National Bearing Company (NBC) under

technical collaboration with Hoffman, U.K.

ii. 1950 Ball Bearing Production started.

iii. 1958 Company is renamed National Engineering Industries Limited (NEI);

NBC Trademark retained.

iv. 1967 Tapered Roller Bearing production started

v. 1975 Spherical Roller Bearings production begins

vi. 1981 Second Plant inaugurated in Newai.

vii. 1982 Cartridge Tapered Roller Bearing in Technical Collaboration with

Brenco Incorporated of U.S.A.

viii. 1985 Technical Collaboration with NTN Corporation of Japan for Ball,

Cylindrical & Spherical Roller Bearing.

ix. 1995 ISO - 9001 Quality Management System Certification

x. 1996 Technical collaboration with Izumi Kinzoku Kogyo Co. Ltd., Japan for

Machine Retrofitting

xi. 2007 Third Plant inaugurated in Manesar.

xii. 2008 NBC receives TPM Excellence Award

xiii. 2010 NBC receives Deming Award

3

xiv. 2012 NBC receives the ACMA awards for Manufacturing and Technology

Excellence

1.3. Technical collaboration

(i) BRENCO Incorporated of U.S.A. Since 1982 - For Cartridge Tapered Roller

Bearings for Railroad applications.

(ii) NTN Corporation of JAPAN Since 1985 - For Ball Bearings, Cylindrical &

Spherical Roller Bearings, JPU Bearings, Double Row Angular Contact Bearings,

Hub Bearings Since 1997 - for Tapered Roller bearings.

(iii) Izumi Kinzoku of JAPAN Since 1996 for remanufacturing, retrofitting and

overhauling of Grinding and Super-finishing machines for bearing races.

1.4. Main Customers

Rolling Stock: -

DLW (Diesel Locomotive Work)

CLW (Chittaranjan Locomotive Works)

ICF (Integral Coach Factory, Chennai)

RCF (Rail Coach Factor, Kapurthala)

CIMMCO

BEML (Bharat Earth Movers, Bangalore)

TEXMACO

Hindustan Motors Ltd.

Maruti Udyog Ltd.

Mahindra & Mahindra

Automobiles-LCV: -

Ashok Leyland

Force Motors

Eicher Motors

Tata Motors

Automobiles-Two/ Three Wheelers:-

Bajaj Auto Ltd.

Hero Honda Motors Ltd.

4

Honda Motorcycle & Scooters India Ltd.

Suzuki Motorcycle India

Majestic Auto

Piaggio India Ltd.

Royal Enfield Ltd.

Yamaha Motors India Pvt. Ltd.

TVS

Tractors: -

Eicher

Escorts

HMT

International tractors

Mahindra & Mahindra

Punjab Tractors

TAFE

VST Tillers

Electric Motors & Pumps:-

Crompton Greaves

G.E. Motors

Kirloskar Electric

NGEF

MICO

Fans: -

Bajaj Electricals

Crompton Greaves

1.5. Manufacturing Facilities

NBC has manufacturing facilities at Jaipur (established in 1946), Newai(established

in 1980) and Manesar (established in 2006). A fourth plant, a green field project,

atSavli in Gujarat will ship out its first bearing in November 2013, ramping up

production capacity to 150 million bearings per year once it is fully operational.

Jaipur Plant

5

Newai (Gunsi) Plant

Manesar Plant

1.5.1. Newai (Gunsi) Plant

Established in the year 1980-81 as an expansion project of NEI Ltd . The factory is

equipped with fully automated grinding lines with electronic in-process & post-

process gauging and centrally air-conditioned assembly lines with auto gauging and

test equipments for quality and reliability of the products,The plant is spread over a

covered area of 7,200 Sq. Meters.

1.5.2 Manesar Plant

NEI has set up its third Ball Bearing manufacturing plant in the fastest growing

industrial town of Manesar in Haryana. The plant is having a covered area of 5200 sq.

meters. with the most advanced and sophisticated machines imported from reputed

manufacturers from Europe and Japan .This plant is equipped with state of the art

fully automated grinding lines, assembly lines and inspection equipments.

Fig1.2: Manesar Plant

6

CHAPTER-2

NBC JAIPUR

2.1. Introduction

This plant is located in the heart of Pink City of India, which is also famous for its

Tourists spots. Spread over a total area of 4,78,900 m2 and a covered area of 75,310

m2, Jaipur plant has state of the art manufacturing facilities and capable to

manufacture all types of Ball and Roller Bearings of NEI product range. . It has a

separate division to manufacture all these spread across large area.

Fig. 2.1: Jaipur Plant

Fig.2.2: Nbc Design and Development

The plant at Jaipur includes-

i. Ball Bearing

ii. Precision Ball Making

7

iii. Tapered Roller Bearing

iv. Railway Bearing

v. Research & Development

vi. Large diameter bearings

vii. SAP-ERP

2.2. Ball Bearing

The latest advanced techniques for manufacturing and Quality Assurance are

implemented to meet the rapid increase in demand for Quality, diversity of

specifications and new types of bearings.

Type of Ball Bearing:-

a. Radial Ball Bearing

b. Angular Contact Bearing

c. Self-Aligning Two-Row Ball Bearing

Radial ball bearing Angular Contact Bearing Self-Aligning Two-Row Ball

Bearing

(a) (b) (c)

Fig. 2.3: Ball Bearings

The initial technology was from Hoffman Manufacturing Company Ltd., U.K. a

collaboration, which continued for 20 years. They offer a wide range of both metric

and inch series deep groove ball bearings, angular contact ball bearings, self-aligning

ball bearings etc. With their tie up with the world's leading bearing manufacturing

company NTN Corporation, JAPAN, They have gained access to the most advanced

8

ball bearing technology i.e. thermo mechanical bearings (TMB) and tensioner

bearings available today and their wide range of ball bearings is increasing under this

collaboration. Precision ball bearing from 6mm bore to 160mm OD is manufactured

with latest advance techniques. The unit has advanced assembly line with auto

gauging and testing equipment. NEI has 22 automatic Grinding lines from M/s. NTN

& Izumi, Japan. All machines with in process & post process gauges to ensure

grinding accuracy. Use of High Quality coolants for consistent grinding quality and

surface finish. Complete automation by flex-link conveyor system. NEI has automatic

plant for Track Grinding, Bore Grinding and Honing, The latest advanced techniques

for manufacturing and Quality Assurances are implemented to meet the rapid increase

in demand for quality, diversity of specifications and new types of bearings. The plant

is spread over a covered area of 14,694 sq. meters.

2.3. Precision Ball Making

Precision Steel balls up to 25 mm diameter for NEI bearings are being manufactured

in a separate well equipped factory. Precision quality balls are manufactured on

precision Grinding & Lapping machines to achieve super finished surface, accuracy

and roundness as per ISO standards. The plant is spread over a covered area of 4,700

sq.mtr.

Fig. 2.4: Steel Ball

2.4. Tapered roller bearing

Type of Tapered Roller Bearing

a. Single Row Tapered Roller Bearing

b. Double Row Tapered Roller Bearing

9

Single Row Tape re d Roller Bearing Double Row Tape r ed Roller Bearin g

(a) (b)

Fig. 2.5: Tapered Roller Bearings

This plant with the most modern equipment was set up in the year 1968.

Manufactured at an ultra-modern plant, with technology obtained from our earlier

collaborators, Federal Mogul Corporation, USA and now with NTN Corporation,

JAPAN, these bearings are used by all major automobiles, truck and tractor

manufacturers in the country as original equipment. The above bearings are

manufacture in inch & metric series form 15.857mm bore to 95.25mm bore. For TRB

NEI has Automatic Grinding Lines with in-process & post process gauges. Complete

automation by Flex link conveyor. Crowning provision on Inner (Cone) & Outer

(Cup). Complete Automatic Line for Roll Grinding, Super finishing, Inspection and

Sorting imported from NTN, Japan automatic checking & prevention of inverted

roller & roller missing. Automatic checking of stand height, noise and run outs.

Presently under modernization and expansion plan the new latest state of the art

technology lines are installed. The plant is spread over a cover area of 11,652 sq. mtr.

2.5. Railway bearing

Railway Bearings included in three sections

a. Roller Bearing & Axle Boxes

b. Spherical Roller Bearing

c. Cartridge Tapered Roller Bearing

2.5.1 Roller bearing & axle boxes

With the production of Roller Bearings and Axle Boxes, since 1952 the company has

10

fully met the requirements of the Indian Railways (one of the largest systems of the

world) by designing and developing axle boxes and bearings for fitment to

Locomotives manufactured by Diesel Locomotive.

Fig 2.6: Axle Boxes

The most of the production of this type of bearing for Indian Railways, Production of

the bearing started in 1952, on date plant is producing 100 different types of Axle Box

bearing, over a million NEI bearings and boxes are in service with the Indian

railways. New Automatic Grinding and Assembly Line has been purchased for

manufacturing of Axle Unit Bearings (DRAC bearings) from M/s Izumi Kinzoku.

2.5.2. Spherical roller bearing

The manufacture of Spherical Roller Bearings was started in the year 1975-76 for

fitment to broad gauge and meter gauge passenger coaches with designs, technology,

machines and equipment procured from the collaborators

Fig 2.7: Railway Bearings

11

2.5.3. Cartridge tapered roller bearing

For fitment to the new BOX-N Uprated Wagons designed by the RDSO, NEI is the

only manufacturer in the country who is the first to indigenize these bearings to a high

percentage under collaboration with the largest manufacturer of these bearings in the

world. Production of these bearings is grease packed and requires no field lubrication

for a period of 7 year. The Railway Bearing Division is spread over a covered area of

1.2 acres.

2.6. Large diameter bearing

Self-sufficiency in steel is the call of the day so is the importance of bearings in steel

Mills Equipment NEI has the distinction of being one of the ten manufacturers of

these bearings up to 2000 mm diameter. The largest bearing produced by NEI for

fitment to plate will of Rourkela Steel Plant was released by Mr. G.P. Birla in

September 1985. This 4-row tapered roller bearing measures 1300 mm diameter and

weighs 4.39 tones. The large diameter bearings are mainly produced out of case

carburizing steels, heat treated on special equipment and furnaces developed by NEI.

The precision grinding is done to close tolerances on CNC Twin Spindle

Programmable Berthiez Machine for bearings ranging from 500 to 2000 mm diameter

with electronic sizing and numerical display. Production of these bearings started in

1975 and to date over 100 different types of special large diameter bearings have been

manufactured and successfully used.

2.7. Research and development

2.7.1. Design and development

Complete in-house facility for design & development of all types of bearings and

tooling is available. The design is done on CAD. The large diameter bearings and

tooling have been entirely designed and developed by NEI’s R&D at its Computer

center. Complete engineering and research facility is available to solve problem of

design development, manufacturing, installation and maintenance of bearings. With

the signing of the technical collaboration agreement with NTN CORPORATION

JAPAN & BRENCO IN CORPORATED OF USA, the capability to offer the finest

engineering services in the bearing industry has enhanced.

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2.7.2. Machine building

The NEI has the capability of Machine Building to design, develop and manufacture

special purpose CNC grinding lines, HT lines, material handling equipment’s and

other special purpose machines, which have been made for its captive use to keep

pace with latest technology A Well-equipped electronic design, development

laboratory with all testing facilities supports the M/c Building division. Machine

Building has the capability and supports the Manufacturing divisions by overhauling

and retrofitting of the existing equipment’s so that these are upgraded to help produce

quality and improve productivity. R& D is spread over a covered area of ½ acres.

2.8. SAP-ERP

In order to re-engineer and integrate the Business processes for Sales, Production,

Materials and Finance, NEI has success- fully implemented SAP ERP.

13

CHAPTER-3

BEARING

3.1. Definition of Bearing

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

typically rotation or linear movement. 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.

Plain bearings are very widely used, and use surfaces in rubbing contact. Particularly

with lubrication they often give entirely acceptable life and friction. On the other

hand, low friction bearings are often important for efficiency, to reduce wear and to

facilitate extended use at high speeds. 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.

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

3.2. Principles of Operation

There are at least six common principles of operation:

• Sliding bearings, usually called "bushes", "bushings", "journal bearings",

"sleeve bearings", "rifle bearings", or "plain bearings”.

14

• Rolling-element bearings such as ball bearings and roller bearings.

• Jewel bearings, in which the load is carried by rolling the axle slightly off-center.

• Fluid bearings, in which the load is carried by a gas or liquid.

• Magnetic bearings, in which the load is carried by a magnetic field.

• Flexure bearings, in which the motion is supported by a load element which bends.

3.3. Motions

Common motions permitted by bearings are:

• Axial rotation e.g. shaft rotation

• Linear motion e.g. drawer

• Spherical rotation e.g. ball and socket joint

• Hinge motion e.g. door

3.4. Loads

Bearings vary greatly over the size and directions of forces that they can support.

Forces can be predominately radial, axial (thrust bearings) or moments perpendicular

to the main axis.

15

CHAPTER-4

CLASSIFICATION OF BEARING

According to nature of relative motion between two contacting surface

There are numerous different kinds of bearings that are designed to handle radial load,

thrust load, or some combination of the two. Because different applications require

bearings that are designed to handle a specific kind of load and different amounts of

weight, the differences between types of bearings concern load type and ability to

handle weight.

4.1. Sliding contact bearing

4.1.1. Hydrodynamic bearing

Load supporting high pressure fluid film is created due to the shape and relative

motion between the two surfaces.

Fig.4.1: Hydrodynamic bearing

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4.1.2. Hydrostatic bearing

The load supporting fluid film is created by an external source, like pump.

Fig. 4.2: Hydrostatic bearing

4.2. Rolling contact bearing

4.2.1. Ball Bearings

Ball bearings are extremely common because they can handle both radial and thrust

loads, but can only handle a small amount of weight. They are found in a wide array

of applications, such as roller blades and even hard drives, but are prone to deforming

if they are overloaded.

4.2.2. Roller Bearings

Roller bearings are designed to carry heavy loads—the primary roller is a cylinder,

which means the load is distributed over a larger area, enabling the bearing to handle

larger amounts of weight. This structure, however, means the bearing can handle

primarily radial loads, but is not suited to thrust loads. For applications where space is

an issue, a needle bearing can be used. Needle bearings work with small diameter

cylinders, so they are easier to fit in smaller applications.

4.2.2.1. Tapered Roller Bearings

This style of bearing is designed to handle large radial and thrust loads—as a result of

their load versatility, they are found in car hubs due to the extreme amount of both

radial and thrust loads that car wheels are expected to carry.

17

CHAPTER-5

MATERIAL USED IN BEARING

5.1. Bearing material

Bearing reliability begins with the material from which the product is made. The

material selection can have a dramatic impact on a bearing’s ability to meet the

application requirements. Additionally, the heat-treatment process that accompanies

material selection largely dictates durability by its impact on several bearing

characteristics, including hardness profile, bearing microstructure, final raceway

surface finish and residual stress.

Traditionally, Bearings have been produced from low carbon, carburizing grades of

steel. The introduction of carbon during manufacture, and the high alloys in the steel,

assures the proper combination of a hard, fatigue-resistant case and a tough, ductile

core. Benefits of casehardened bearings include:

Residual compressive stresses in the surface that retard propagation of fatigue cracks.

An enhanced ability to endure heavy shock loads as a result of the tough, ductile core.

Improved debris resistance due to the metallurgical characteristics of the surface

Tapered roller bearings have a spherical surface ground on the large ends of the

rollers. The radius of this surface is slightly less than the apex length (distance from

the roller large end to the apex). The roller large end makes point contact with the

cone large rib when under light load. Under heavier load, this contact area becomes

elliptical. The roller rib interface geometry promotes hydrodynamic lubrication in the

contact area. The seating force of the roller against the rib is normally small and

therefore contact stresses are relatively low. This is true whether pure radial load or

pure thrust load is involved.

18

5.2 Flow of Material in Bearing

Fig.5.1: Flow of Material in Bearing

19

CHAPTER-6

TAPERED ROLLER BEARING

6.1. Introduction

Tapered roller bearings are bearings that can take large axial forces (i.e., they are

good thrust bearings) as well as being able to sustain large radial forces.

The inner and outer ring raceways are segments of cones and the rollers are also made

with a taper so that the conical surfaces of the raceways and the roller axes if

projected, would all meet at a common point on the main axis of the bearing.

Fig.6.1: Tapered roller bearings

Fig.6.2: Tapered roller bearing components

This conical geometry is used as it gives a larger contact patch, which permits greater

loads to be carried than with spherical (ball) bearings, while the geometry means that

20

the tangential speeds of the surfaces of each of the rollers are the same as their

raceways along the whole length of the contact patch and no differential scrubbing

occurs. When a roller slides rather than rolls, it can generate wear at the roller-to-race

interface, i.e. the differences in surface speeds creates a scrubbing action. Wear will

degenerate the close tolerances normally held in the bearing and can lead to other

problems. Much closer to pure rolling can be achieved in a tapered roller bearing and

this avoids rapid wear.

The rollers are guided by a flange on the inner ring. This stops the rollers from sliding

out at high speed due to their momentum.

The larger the half angles of these cones the larger the axial force that the bearing can

sustain.

Tapered roller bearings are separable and have the following components: outer ring,

inner ring, and roller assembly (containing the rollers and a cage). The non-separable

inner ring and roller assembly is called the cone, and the outer ring is called the cup.

Internal clearance is established during mounting by the axial position of the cone

relative to the cup.

6.2. Product Subtypes

6.2.1. Single Row (TRB)

Fig.6.3: Single Row (TRB)

21

6.2.2. Double Row (TRB)

Fig.6.4: Double Row (TRB)

6.2.3. Four Row (TRB)

Fig.6.5: Four Row (TRB)

6.2.4. Tapered Roller Thrust

Fig.6.6: Tapered Roller Thrust

22

CHAPTER-7

PROCESS OF MANUFACTURING

7.1. Manufacturing Processes of Tapered Roller Bearing Bearing

NBC gets forged and roller bearings from their vendors, as there are no separate dept.

for forging or rolling. Than they do carburizing or other heat treatment to strengthen

the bearing or finally grinding or other finishing operation is performed to make it

able to operate in automotive vehicle, railway etc. The processes through which

bearing has to go are shown in flow diagram below-

Fig.7.1: Manufacturing Processes of Tapered Roller Bearing Bearing

23

7.2. Heat treatment and laboratory

Heat treatment of bearing steel components necessitates heating and cooling under

controlled atmospheric conditions to impact the desired material characteristics and

properties such as hardness, a diffused high carbon surface layer, high fracture

toughness or ductility, high tensile strength, improved machinability, proper grain

size, or reduced stress state. The specific thermal cycles that produce these material

characteristics are:

(i) Annealing

(ii) Normalizing

(iii) Hardening

(iv) Carburizing

(v) Tampering

(vi) Stress Reliving.

Fig.7.2: Heat treatment sequence

24

Let’s discusses each process with respect to these parts for simplicity of

understanding

Fig: 7.3: Flow diagram of heating sequence of spherical bearings

7.3. Carburizing

Carburizing is a is a heat treatment process in which iron or steel absorbs carbon

liberated when the metal is heated in the presence of a carbon bearing material, such

as charcoal or carbon monoxide, with the intent of making the metal harder.

Depending on the amount of time and temperature, the affected area can vary in

carbon content. Longer carburizing times and higher temperatures lead to greater

carbon diffusion into the part as well as increased depth of carbon diffusion. When the

iron or steel is cooled rapidly by quenching, the higher carbon content on the outer

surface becomes hard via the transformation from austenite to martensite, while the

core remains soft and tough as a ferritic and/or pearlite microstructure.

25

The carburizing is performed 940º to 980ºc in rotary hearth furnace with time of

10hrs. But carburizing is done for only cup and cone with Air: LPG =10:1 (Endo

Gas).

Fig.7.4: Rotary hearth furnace

7.4. Hardening Furnace

To control the mechanical properties, it is essential to start a structure with a structure

of austenite since it is state where the carbon atoms are distributed into the iron matrix

uniformly. The austenitic structure in steel is achieved by heating it and soaking at a

temperature above 7230C, depending on the carbon percentage.

In hardening furnace “case hardening” of the job is carried out in the presence of R-

Gas. R-Gas is a mixture of CO+H2+N2+CO2+H2O. R-Gas is formed by the reaction of

LPG with air. This reaction is taken place in retort at a temperature of 950 0C in the

presence of catalyst.

Hardening furnace has four chambers. First chamber is at 840 0C and rest three

chambers are at 850 0C. After the hardening furnace bearing material (steel) is

converted into austenite form.

7.5. Quenching

Quenching is a process of cooling a metal at a rapid rate. This is most often done to

produce a martensite transformation. In ferrous alloys, this will often produce a harder

metal, while non-ferrous alloys will usually become softer than normal. To harden by

26

quenching, a metal (usually steel or cast iron) must be heated above the upper critical

temperature and then quickly cooled.

In NBC Oil is used in the quenching process and the oil is kept at a temperature of

250C. Agitator is used to stir the oil in the oil quenching tank.

From the figure 4.3, we can find that when we rapidly cool austenite form then

martensite will form and it will have more hardness in comparison to austenite form.

Then through the conveyor job is sent to the washing tank which is held at a

temperature near about 220C. The conveyor speed is 400 mm/Min. Then drying is

done with the help of air.

7.6. Tampering

Martensite formed during the quenching process is extremely hard and brittle, and

lack toughness. Thus these steels are not suitable for some baring applications

requiring impact resistance; hence a secondary heat treatment process called

tempering is carried out on quenched steel to achieve the necessary toughness and

ductility by marginally sacrificing hardness. This process also relives the internal

stresses thus improving the ductility. The tempering temperature is about 200 C for

2.5 hrs. The above mentioned time and temperatures during heat treatment

explanations are for cup, cone, and wear rings.

Fig.7.5: Tempering furnace

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7.7. Rockwell hardness test

To see the effect of tampering on bearing races Rockwell hardness test is being used

to check the hardness of races before and after the tampering. Before the tampering

hardness range lies between is 62 to 64 HRC and after tampering hardness range is

60-62HRC. The overall effect of tampering also affects the hardness and this reduced

by 2HRC.

Principal of the Rockwell Test

The indenter moves down into position on the part surface

A minor load is applied and a zero reference position is established

The major load is applied for a specified time period (dwell time) beyond zero

The major load is released leaving the minor load applied

The resulting Rockwell number represents the difference in depth from the zero

reference position as a result of the application of the major load. If HRC doesn’t

meet our requirements then we reject the tampered lot. Behind this there may be

following causes-

a) Manufacturing Fault

b) Furnace temperature fault

c) Tampering fault

28

Fig.7.6: Rockwell hardness test setup

7.8. Grinding Section

Grinding is a finishing process used to improve surface finish, abrade hard materials,

and tighten the tolerance on flat and cylindrical surfaces by removing a small amount

of material. In grinding, an abrasive material rubs against the metal part and removes

tiny pieces of material. The abrasive material is typically on the surface of a wheel or

belt and abrades material in a way similar to sanding. On a microscopic scale, the chip

formation in grinding is the same as that found in other machining processes. The

abrasive action of grinding generates excessive heat so that flooding of the cutting

area with fluid is necessary.

During the grinding operations coolant is used regularly. Coolant is mixture of water

and oil. In coolant percentage of oil 3.5% and rest is water. For O.D grinding in N.E.I.

Ltd. HOCUT B-60 oil is used.

29

7.9. Assembly section

The assembly part in NEI is done manually. The parts after going through various in

line inspection or a separate inspection for all bearing components sent to assembly

line. In assembly line each parts width, bore, track is checked again through various

gauges.

Assembly of Spherical Roller Bearings Components: -It includes

a) Inner race.

b) Outer race.

c) Roller section (Retainer Section).

d) Roller Cage.

Fig.7.7: Elements after assembly of spherical bearings

7.10. Maintenance and inspection section

7.10.1 For machines

Maintenance and inspection is that section where various types of machines, tools and

machine parts are inspected for life requirement and better working features. Various

types of pressure gauges, vibration inspection machines and the noise inspection

machines are the special features of this section.

30

Maintenance and inspection is that section where various types of machines, tools and

machine parts are inspected for life requirement and better working features. Various

types of pressure gauges, vibration inspection machines and the noise inspection

machines are the special features of this section.

The machines used in this section are as follows -

i. LATHE m/c,

ii. SHAPER m/c,

iii. BORING m/c,

iv. PLANNER m/c,

v. DRILLING m/c,

vi. MILLING m/c,

vii. Universal type,

viii. Vertical and Common type, Plain Milling m/c

7.10.2. For bearing components

All these inspections are done manually

Inline Inspection- after every specific operation there is checking of bearing

components (1 out of 20) through gauging processes like width, track or bore gauge

after width, bore or track grinding Resp.

Final Inspection- when the complete grinding of a particular product is completed like

for cone all processes width, bore or track grinding is completed than it sent to final

inspection.

In Final Inspection we detect crack check by two methods:

a. Crack check Machine - kerosene or magnetic flux is used

b. Demagnetize Washing

31

CHAPTER-8

MANUFACTURING & ASSEMBLY

8.1. Inner & Outer Ring Manufacturing

Fig.8.1: Flow Chart of Inner & Outer Ring Manufacturing

The contact surfaces of the bearing rings and rolling elements are subjected to

repeated heavy stresses, so they must maintain high precision and rotational accuracy.

To accomplish this, the rings and rolling elements must be made of a material that has

high hardness, resistant to rolling fatigue, wear resistant and has good dimensional

stability.

32

High carbon chromium bearing steel (SUJ 2) deep hardened by the hardening method

&case hardening steel (SC/SCM/SNCM) with a hardened carburized outer layer are

used for the rings and rolling elements of standard bearings.

The most widely used and most suitable materials for rolling bearings are high carbon

steels. The most commonly used of these steels is SUJ2. For bearings with large cross

section dimensions SUJ3 or SUJ5 having good hardening properties are used. NBC

uses high carbon steel for almost all of spherical roller & cylindrical roller bearings.

For case hardening steel; Chrome Steel (SCr), Chrome Molybdenum Steel (SCM)

and Nickel Chrome Molybdenum Steel (SNCM) are used because of its combination

of a hard surface layer which has been carburized and hardened to an appropriate

depth, and a relatively pliable inner core, case hardening steel has excellent efficiency

against shock load. NBC uses case hardening steel for almost all of tapered roller

bearings.

Since the life of the bearing steel is determined by the purity of cleanliness of steel the

above grade steels are low in non-metallic impurities & low in oxygen content

because they are refined by a vacuum degassing process & outside hearth smelting

process.

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

&Bore. All these operations are done on production lathe machines. The Hardening of

steel is achieved by heat treatment process in which the steel microstructure is

manipulated by cycles of heating & quick cooling to obtain the optimum hardness

range for steel – usually on the order of 60 to 64 on Rockwell C Hardness Scale.

When slowly quenched it would form Austenite & Pearlite which is a partly hard and

partly soft structure respectively. Hardening of steel requires a change in structure

from Body Centered Cubic Structure found at room temperature to Face Centered

Cubic Structure found in Austenite Region. When Steel is suddenly Quenched Marten

site is formed which is extremely strong and if steel is Quenched slowly then Pearlite

is formed which is extremely Soft.

33

8.2. Roller Manufacturing

Fig.8.2: Manufacturing of Roller

The Raw Material used (SUJ 2 Steel) for manufacturing of rollers is a specially

formulated grade of Steel. The Material is Supplies by rod. It is then cut to length

&width on Production Lathe.

For Spherical Rollers or Tapered Rollers, The rod is then fed through a header. This

cold forged process produce “slugs” at an incredibly high speed. Rod is fed from

34

decoilers into cold heading machines where it is cut into blanks and then pressed

between hemispherical dies or conical dies. For Cylindrical Rollers the above

procedure is not done.

The flash around the rollers produced during pressing is removed by filing plates in

deburring machines. These rough shaped spherical rollers have a ring around the

middle. The next process is to remove this ring by machining in rill-filing machine,

equipped with one fixed and one rotating cast iron rill-plate. Concentric grooves in the

plate ensure that the whole roller surface is machined to same extent and thus a

spherical form is achieved

The next process for Rollers is grinding in which rollers are grind in the order: Face,

O.D. and I.D. The grinding process is done in two phases; one prior to Heat

Treatment (Rough Grinding) & one after the heat treatment process (Finish

Grinding).Final inspection for size, form and surface finish is carried out on a sample

basis by means of high resolution microscopes and other precision equipment because

a tiniest deviation even of the order of 1 Å (10-10m) in the roundness of bearing

element can have an impact on bearing quality. The rollers are then cleaned and

dispatched for bearing assembly operation.

8.3. Cage Manufacturing

Fig.8.3: Cage Manufacturing

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The cages for various bearing sizes are manufacture from Cold Rolled (C.R.) & Cold

Annealed narrow width sheets IS 4397. The C.R. sheet is converted in the cage in

Press Machine in Successive Operations: Blanking, Punching, Forming (Pocketing)

rivet holes and visual inspection is carried for any deformity.

8.4. Roller Bearing Assembly Line

The assembly part in NEI is done manually. The parts after going through various in

line inspection or a separate inspection for all bearing components sent to assembly

line. In assembly line each parts width, bore, track is checked again through various

gauges.

Flow Chart

Fig.8.4: Roller Bearing Assembly Line

36

CHAPTER-9

APPLICATIONS

While Engineered Surfaces have been successfully applied to a variety of

components, our first and most extensive experience is using these processes with

anti-friction bearings. Timken research revealed that modifying the topography of a

bearing’s contact surfaces resulted in significant improvement in overall performance.

Inadequate lubrication, poor maintenance, extreme operating environments and

vibration can be detrimental to bearing performance. Engineered Surfaces enable

bearings to better resist these potentially damaging environmental factors.

Real-world benefits have been demonstrated in rugged applications that include

bearings used in aircraft landing gear, heavy equipment drive trains and industrial

rolling mills.

In many applications tapered roller bearings are used in back-to-back pairs so that

axial forces can be supported equally in either direction.

Pairs of tapered roller bearings are used in car and vehicle wheel bearings where they

must cope simultaneously with large vertical (radial) and horizontal (axial) forces.

Applications for tapered roller bearings are commonly used for moderate speed,

heavy duty applications where durability is required. Common real world applications

are in agriculture, construction and mining equipment, axle systems, gear box, engine

motors and reducers

37

CHAPTER-10

CONCLUSION

My training period of 45 days turned out to be a wonderful experience both

industrially and learning wise; experiencing the functionalities of Heavy Fabrication

Block, flow of knowledge as well as decision making processes within the block.

Working with the employees and learning from them was such a life changing

experience.

This report describes the NBC bearing industry and its technology. My Through this

report, I have tried to present a comprehensive study of the various functionalities and

responsibilities of NBC Bearings. Starting from the overview of the company till the

explanation of various type of process i.e. heat treatment, grinding, facing and the

different type of machines used in that processes like for grinder, machines for honing

& super finishing machines are available, for heat treatment rotary hearth furnace and

tampering furnace and CNC machines. This report tries to throw light on each and

every aspect of the NBC Bearings.

Maximum of their work was done manually. While in railway bearing division, the

whole processing is automatic. But now days they are trying to set up new NOVA

CNC machines. It will reduce the human effort or will increase productivity up to a

large extent. This setting up of new nova machines will place the NBC at a position to

compete with other worldwide bearing manufacturing companies.