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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.
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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
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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.
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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
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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
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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
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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
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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
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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
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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
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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.
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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”.
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• 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.
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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.
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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.
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5.2 Flow of Material in Bearing
Fig.5.1: Flow of Material in Bearing
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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
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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)
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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
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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
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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
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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.
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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
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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
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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.
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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.
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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
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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.
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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.
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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
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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
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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
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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.