Training Report

PRACTICAL TRAINING REPORT

(40 WORKING DAYS)DURATION: - (16th MAY, 2006 To 26th JUNE, 2006)

TAKEN AT

National Engineering Industries Ltd.Khatipura Road, Jaipur – 302006, India.

Submitted To Prepared By Ms. Monika Joshi Suman Yadav Sr. Manager (H.R.D.) B.E. II Yr. (Mechanical Engg.) NEI Ltd., Jaipur M.B.M. Engg. College, Jodhpur

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INDEX

Preface Acknowledgement Company Profile Product Information Ball Bearing Railway Bearing Taper Roller Bearing Large Diameter Bearing Other Divisions

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PREFACE

Practical training is an essential part of an engineering student as it adds to the technical knowledge of the student. It gives the student the much needed exposure to the real world and helps him to relate his theoretical knowledge with the field conditions. As a part of engineering curriculum each student has to undertake it for a prescribed duration.

According to our syllabus each student of B.E. II year Mechanical has to complete a training of 40 days.

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ACKNOWLEDGEMENT

I feel immense pleasure in thanking Ms. Monika Joshi, Sr. Manager, NEI Ltd., for giving me an opportunity to take my training in NEI Ltd.

I also extend my thanks to Mr. Thomas for helping me throughout my training.

I also express my sincere gratitude to Mr. Amit Sharma, Mr. Arvind Sharma, Mr. Rajkumar Ajmera, Mr. Shashikant Sharma, Mr. Niranjan Sharma and Mr. Rishi Sharma for guiding me throughout my training.

I also thank all the engineers, supervisors, and workers without whom this training would not have been a successful one.

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COMPANY PROFILE

This factory was established in Jaipur in year 1946 by Mr. B.M. Birla under name of

National Bearing Company (N.B.C.) limited. In 1950 it manufactured its first bearing and

it was marketed under trade name N.B.C. Company changed its name to National

Engineering Industries (N.E.I.) limited in 1958 but the product is being sold under the

original trade mark of N.B.C. which had now become a symbol of quality.

It is the largest manufacturer of bearings in India. The NEI produces all type of bearings

and axel box completed with roller bearings.

The branch offices of NEI limited are at Mumbai and Calcutta and the sales

representatives are in Amritsar, Coimbatore, Kanpur and Secunderabad.

The company also has business in United Kingdom, Japan, Germany, Yugoslavia, United

Arab Emirates and Iran. The plant has an area of nearly 15, acres. The company has over

1500 workers working in three shifts for twenty four hours.

The major products of company are as follows:

Ball bearing

Taper roller bearing

Axle box bearing

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

Motors, Railway wagon, Coach and Locomotive manufacturers as Original Equipment

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

Power Plants all across the country.

The NEI Office Network

HEAD OFFICE

The Head Office of the Company is situated at 9/1 R.N. Mukherjee road in Kolkata.

COMPETITORS

(1) S.K.F. Poona

(2) S.B.L. Ranchi

(3) ABC Ranchi

(4) KOYO India , Hyderabad

(5) FAG , Mumbai

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(6) Bharat Ball Bearing

(7) Tata, Jamshedpur

PLANT AT JAIPUR

PLANT INFORMATION

The factory is situated at khatipura road about one kilometer west of railway station,

Jaipur. The choice of its location has been so made because of its proximity with railway.

This brings down the cost of material vending from to the factory. The raw material

cheaply and easily obtained by goods train. Similarly the final product can also be

transported to the demanded areas from the factory.

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PRODUCT INFORMATION

(i) Ball Bearing:

Precision Ball Bearings from 6 mm bore to 75 mm bore diameter are manufactured on

state of the art manufacturing facilities with in-process and post-process gauging in

grinding and centrally air conditioned assembly lines with auto gauging and testing

equipments. 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. This Division is spread over a covered area of 14,694 Sq.

Meters.

(ii) Steel Ball:

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Precision Steel Balls up to 25 mm diameters for NBC Bearings are manufactured on

precision grinding and lapping machines to achieve super finished surface, accuracy and

roundness as per ISO standards. This Division is spread over a covered area of 4,700 Sq.

Meters.

(iii) Tapered Roller Bearing:

Precision Tapered Roller Bearings are manufactured in Inch and Metric series from

15.875mm bore to 95.25mm bore with technology obtained from our earlier collaborator,

Federal Mogul Corporation, USA and now with NTN Corporation, Japan. These bearings

are used by all major Automobile manufacturers in the country as Original Equipment.

This Division is spread over a covered area of 11,652 Sq. Meters.

(iv) Railway Bearing:

(a) Roller Bearing in Axle Box:

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

company has 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

Works, Chittaranjan Locomotive Works, various wagon builders, the ICF

broad and meter gauge coaches. Over a million NBC bearings and boxes are

in service with the Indian Railways. The development of completely

indigenized Axle Boxes and bearings for the high speed Rajdhani

Locomotive, the Yugoslavian and Egyptian Railway wagons are the highlights

of the design capabilities at NEI. On date more than 100 types of Axle Boxes

& Bearings have been manufactured.

(b)Spherical Roller Bearing:

The manufacturing 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.

(c)Cartridge Tapered Roller Bearing:

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For fitment to the new BOX-IN Up grated Wagons designed by the RDSO,

NEI is the only manufacturer in the country to indigenized these bearings to a

high percentage under collaboration with the largest manufacturer of  these

bearings in the world. Production of these bearings commenced in the year

1984. These bearings are grease packed and require no field lubrication for a

period of 7 years. This Division is spread over a covered area of 4,855 Sq.

Meters.

(v) 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 in the world, who can manufacture large diameter bearings up to 2000 mm

diameter.

The largest bearing manufactured by NEI for fitment to the Plate Mill of Rourkela Steel

Plant was released by Mr. G.P. Birla in September 1985. This 4-Row Tapered Roller

Bearing measures 1300 mm dia and weigh 4.39 tons.

The large diameter bearings are mainly manufactured out of case carburizing steel, heat

treated on special equipment and furnaces developed by NEI. Precision grinding is done

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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, saving

considerable foreign exchange for the country. The Large Diameter Bearings Division is

spread over a covered area of 2,508 Sq. Meters.

The following New Bearings are Developed for Railway Application

SPHERICAL ROLLER BEARINGS

22312D1 (Bore 60 mm x OD 130 mm x Width 46 mm)

22312KD1 (Bore 60 mm x OD 130 mm x Width 46 mm)

22314D1 (Bore 70 mm x OD 150 mm x Width 51 mm}

22314KD1 (Bore 70 mm x OD 150 mm x Width 51 mm)

22222 (Bore 110 mm x OD 200 mm x Width 53 mm)

22222KD1 (Bore 110mm x OD 200 mm x Width 53mm)

CYLINDRICAL ROLLER BEARINGS

NH318 (Bore 90 mm x OD 190 mm x Width 43 mm) Traction Motor Bearings

NU1964 (Bore 320 mm x OD 440 mm x Width 56 mm)

Suspension Bearing developed for Indian Railways for WAG-9 Locomotive

NH1044 (Bore 220 mm x OD 340 mm x Width 56 mm)

Suspension Bearing developed for Indian Railways for WAG-9 Locomotive

SUSPENSION TUBE KIT ASSEMBLY

Suspension tube kit assembly developed for Indian Railways for GM Locomotive WDG-

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TAPERED ROLLER BEARING

M244249A/N1060 (Bore 220.662 mm x OD 314.325 mm x Width 61.912 mm)

Suspension Bearing developed for Indian Railways for GM Locomotive WDG-4

N1059/M244210 (Bore 221.17 mm x OD 314.325 mm x Width 61.912 mm)

Suspension Bearing developed for Indian Railways GM Locomotive WDG-4

COLLBORATORS OF N.E.I. Ltd.

The National Engineering Industries Limited the oldest bearing manufacturing industry

established as the National Bearing Co. Ltd. In 1946 at the Pink city of India, Jaipur had

association and technical collaboration with renowned world manufacturers.

1. The Hoffman Manufacturing Co. Chelmsford, U.K. (Now RHP)

2. Withelm Stahtecker GMBH, West Germany

3. Federal Mogul Corporation, U.S.A.

4. SRO Switzerland

5. Heald Incorp. Ltd, Boston U.S.A.

6. NTN, Japan

7. Brenco U.S.A.

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ISO / TS 16949:2002

NEI extensively embarked upon system improvement and implemented modern concepts

of Total Quality Management. NEI has been awarded TS 16949: 2002 on 17th October,

2003- THE MARK OF EXCELLENCE IN QUALITY MANAGEMENT SYSTEMS

by BVQI for design, development, manufacture & supply of Ball Bearing, Tapered

Roller Bearing and Cylindrical Roller Bearings. NEI Ltd. is the first bearing industry in

India to have been recommended for TS 16949: 2002.

This certificate is awarded to only suppliers of automobile manufacturers. NBC bearings

are used by all major auto mobile companies’ in India like Maruti Udyog, Hero Honda,

Bajaj Auto, Bajaj Tempo, TVS Motors, Ashok Leyland, Tata Motors, Hindustan Motors,

Yamaha Motors, Eicher Limited, Eicher Motors, Mahindra & Mahindra Auto & Kinetic

Motors etc.

In addition customers like Eicher Tractors, Punjab Tractor, Escort Tractor, International

Tractors, New Holland Tractors, Electric & Pump Motors, Crompton & Orient Fans and

many more in Automobile, Electric Motors & Pump, Fans, Conveyors, Steel Plants, and

Thermal Plants also use NBC bearing regularly.

The recommendation was made by BVQI after 15 days of detailed audit in all areas of

NEI including their Gunsi plant.

ISO 9001:2000

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NEI’s Large dia bearing division and railway bearing division which are

manufacturing Cylindrical Roller Bearings, spherical roller bearings, cartridge tapered

roller bearings, railway rolling stock and spares has also been awarded to

ISO 9001: 2000 on 9th October, 2003 by BVQI.

ISO 14001:1996

NEI’s everlasting concern for cleaner, pollution free environment has made the NEI to go

on the path of Environmental management System. NEI was awarded ISO -14001

certificates by BVQI in the month of March 2000 for Environmental Management

System. NEI has done tremendous efforts in resource conservation, recycling and thick

plantation. The efforts at NEI have saved precious natural resources like water, oil and

power etc.

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BALL BEARING

There are four major parts in a standard ball bearing: balls, the inner race, the outer race and the cage.

BALLS

The Manufacturing Process

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HEADING - The balls are a little more difficult to make, even though their shape is very simple. Surprisingly, the balls start out as thick wire of high chromium high carbon steel. This wire is fed from a roll into a machine that cuts off a short cylindrical piece, and then smashes both ends in towards the middle in between a steel die and punch giving it its round shape. This process is called cold heading. Its name comes from the fact that the wire is not heated. The ball formed has a ring like shape called “flash”, around its surface due to the fact that the volume of wire fed into the die and punch is more than the volume of ball to be made and this excess of metal forms this ring. The excess metal is given so that no defect occurs in ball during heading.

Ball Machine

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Rill plates for ball machine

FLASHING - The first machining process removes this flash. The balls are put between the faces of two cast iron disks, where they ride in grooves. The inside of the grooves are rough, which tears the flash off of the balls. One wheel rotates, while the other one stays still. The stationary wheel has holes through it so that the balls can be fed into and taken out of the grooves. A special conveyor feeds balls into one hole, the balls rattle around the groove, and then come out of the other hole. They are then fed back into the conveyor for many trips through the wheel grooves, until they have been cut down to being fairly round, almost to the proper size, and the flash is completely gone. Once again, the balls are left oversize so that they can be ground to their finished size after heat treatment. The amount of steel left for finishing is not much; only about 8/1000 of an inch (.02 centimeter), which is about as thick as two sheets of paper.

HEAT TREATMENT - Various operations in heat treatment:

1. Loading2. Pre-washing in hot water to make it fully clean3. Hardening in furnace at 850-900 Degree Centigrade4. Quenching in oil at 105-110 Degree Centigrade 5. Washing in hot water with soda to remove oil6. Tempering at 150-200 Degree Centigrade to remove stresses developed in

quenching

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This is done in CHUGAI-RO furnace which is completely automatic plant for heat treatment which requires least space, manpower and time.

GRINDING - After heat treatment, the balls are put back into a machine that works in the same way as the flash remover, except that the wheels are grinding wheels instead of cutting wheels. These wheels grind the balls down so that they are round and within a few ten thousandths of an inch of their finished size.

LAPPING - After this, the balls are moved to a lapping machine, which has cast iron wheels. Here, they will be lapped for 8-10 hours, depending on how precise a bearing they are being made for. Once again, the result is steel that is extremely smooth.

RACES

HEAT TREATMENT - Manufactured races are heat treated. They undergo the same operations as the balls.

FACE GRINDING - Next process is face grinding. There are two kinds of machines used for face grinding. The first kind is in which there is only one grinding wheel and thus one face is grounded at a time. To reduce this time taken, a new machine has been introduced in which there are two grinding wheels rotating in opposite directions with same speed so that both the faces can be grounded simultaneously. There are two machines of this kind, first, ROWLAND MACHINE, having grinding wheels with horizontal spindle, which is used for rough face grinding, and the other one is DISCUSWERKE MACHINE, having grinding wheels with vertical spindle, which is used for finish face grinding. A diamond point tool is used for dressing the grinding wheel as it wears out due to continuous working and looses its shape. A coolant is used to prevent the heat generation due to grinding.

O.D. GRINDING - After face grinding outer diameter of inner and outer races is ground. For this purpose centreless grinding machines are used. There are two wheels, grinding and regulating wheel, in the machine. The centres of these two wheels are not aligned and thus the job is not centered between the two wheels, so it is called centreless machine. The job is held against the face of grinding wheel by the combination of supporting rest and a regulating wheel. Both wheels rotate in the same direction, but the speed of regulating wheel is very less than grinding wheel. Grinding wheel rotates about its horizontal axis during working process. The work piece is supported on a work rest blade and regulating wheel which hold it against the horizontal force of action controlling its size. Relational and longitudinal feed are given to the races. The edge of the work rest blade is beveled, so it makes a “v” formation with the regulating wheel, when races are set. A roller of very small diameter compared to its length is provided for loading of the races. This rotates at very slow speed in the same direction of rotation to that of regulating wheel. Work pieces are loaded manually on this roller.

INNER RACE TRACK GRINDING – IZUMI KN 312 is used for track grinding of inner race. A large diameter grinding wheel, having proper shape for

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track grinding, rotates at high speed. Inner race is fed through a channel in the machine and clamped in magnetic chuck. Grinding wheel then moves towards the race and grounds it. After grinding, grinding wheel moves back and race comes out through another channel. Grinding on surface is maintained through a MARPOSS GAUGE. A skilled operator sets this electric gauge according to the required finished size. It consists of a thin resistance wire which is connected to a diamond point tool. After rough grinding of the job surface, this tool comes automatically in surface contact. As the metal is removed continuously by grinding wheel, this diamond point tool moves in the direction of “Depth of Cut” and this movement increases the length and resistance of wire as well, related to the number appeared on the screen, shows the limit of grinding. Machines are connected with PLCs for automatic control.

OUTER RACE TRACK GRINDING – CINCINNATI MILACRON machine consists of a grinding wheel smaller in diameter than outer race track diameter. Initially, race is clamped in a chuck through a channel and then wheel enters into race according to feed. Race is supported by bush and backing plate. Now wheel reciprocates along the direction of its axis.

BORING – The bore of the inner race is also grounded in the similar fashion. The diameter of grinding wheel is slightly less than that of bore. Rest is similar to outer race track grinding.

HONING – It is the process super finishing the surface of the tracks. Types of stones are used for rough and final finishing. They are made of aluminium oxide and chromium oxide respectively. These stones rub the surface of the track giving it a polished look.

CAGE

Steel cages are stamped out of fairly thin sheet metal, much like a cookie cutter, and then bent to their final shape in a die. A die is made up of two pieces of steel that fit together, with a hole the shape of the finished part carved inside. When the cage is put in between and the die is closed, the cage is bent to the shape of the hole inside. The die is then opened, and the finished part is taken out, ready to be assembled.

Plastic cages are usually made by a process called injection molding. In this process, a hollow metal mold is filled by squirting melted plastic into it, and letting it harden. The mold is opened up, and the finished cage is taken out, ready for assembly.

ASSEMBLY

Now that all of the parts are made, the bearing needs to be put together. First, the inner race is put inside the outer race, only off to one side as far as possible. This makes a space between them on the opposite side large enough to insert balls between them. The required number of balls is put in, then the races are moved so that they are both centered, and the balls distributed evenly around the bearing. At this point, the cage is installed to hold the balls apart from each other. Plastic

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cages are usually just snapped in, while steel cages usually have to be put in and riveted together. Now that the bearing is assembled, it is coated with a rust preventative and packaged for shipping.

A Completely Assembled Bearing

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AXLE BOX DIVISION

INTRODUCTION – The axle box division is spread in a vast area and is equipped with modern CNC machines where the spherical roller bearings, taper roller bearings, cylindrical roller bearings and, ruction motor bearings are manufactured to provide bearings to Indian Railways and for exporting.

The axle box division mainly consists of three sections as – heat treatment, grinding and, assembling.

HEAT TREATMENT – The races are first of all heat treated in various furnaces according to the material they are made up of, high carbon steel or low carbon steel.

1. HEAT TREATMENT BY ROTARY FURNACE – The job is taken inside the rotary furnace maintained at a temperature of 850 Degree Centigrade. This furnace is generally driven by LPG and here the job is heated for about 45 minutes. Now the job is Quenched into the oil having a temperature of about 60-70 Degree Centigrade for about 2 minutes. The job is now subjected into the chiller unit for its cold treatment in which the total heat is reduced for 2 minutes. Now the job is sent to the tempering furnace at a temperature of 250 Degree Centigrade. Finally it is sent to the hardness testing machine.

2. HEAT TREATMENT BY GAS CARBURIZING FURNACE – After stamping process, the raw material is sent to this furnace where the job is to give high carbon content at a temperature of 940 Degree Centigrade for about 8 hrs so that the percentage of carbon increases to 80 – 90%. This furnace uses a mixture of LPG and endo gas as the fuel. LPG acts as the source of carbon and endo is used to extract carbon from LPG and to provide inert atmosphere in the furnace. The job is then sent to rotary furnace for heating at 850 Degree Centigrade and is then Quenched in oil and is further chilled. The job is then sent to the tempering furnace maintained at 250 Degree Centigrade for 2.5 hrs. The job is finally sent to the hardness testing machine.

3. HEAT TREAYMENT BY REVOLVING FURNACE – The revolving furnace is the heat treatment electric furnace which is used to harden the job placed in a

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circular plate and revolve by the gear arrangement at a temperature of 840 – 850 degree Centigrade. The job is then Quenched in oil at a temperature of 60 – 90 Degree Centigrade and is further sent to tempering furnace, followed by hardness testing machine.

4. SALT FURNACE-This furnace is used for hardening high carbon steel jobs, where first of all the job is heated in a furnace at a temperature of about 840 Degree Centigrade for some time and is then quenched into a chromium salt container at a temperature of 180 Degree Centigrade and is then send for grinding process.

5. SHOT BLAST MACHINE – The job as hardened by the revolving or salt bath furnace is sent to the shot blast machine where the job is rotated in presence of chilled iron. During this process all of the dust is removed and we obtain a polished surface over the job.

RACE GRINDING – The race grinding follows the same order to that of ball bearing, i.e. face followed by O.D. and track grinding.

1. SPHERICAL ROLLER BEARING – The face and O.D. grinding is similar to that of ball bearing races’ grinding. For track grinding, grinding wheel is fed into the outer race such that the axis of the grinding wheel crosses the axis of the outer race normally. In case of inner race, both the lips touching the rollers are grounded together followed by track grinding.

2. TAPER ROLLER BEARING – It consists of a cup (outer race), and two cones (inner race). In case of cup, first of all O.D. is grounded, followed by the track. The grinding wheel is similar to that of track in shape, i.e. it is tapered such that it easily feeds into the cup. In case of cone, face is grounded followed by the flange where the cage touches the cone. After that track and the lip (where rollers touch) are grounded simultaneously so that the angle between lip and track is constant. The shape of the grinding wheel is maintained such that these two surfaces can be grinded together. It is followed by boring.

3. CYLINDER ROLLER BEARING – The races are grounded in similar fashion to that of ball bearing races. Flange and lip may or may not be grounded as according to the requirement of the final bearing.

ROLLER GRINDING – The grinding wheel is given the particular shape with the help of diamond point so that the rollers can be given the required shape. The process starts with grinding twice and then honing is done.

PHOSPHATING – The bearing races undergo phosphating, i.e. phosphate coating is done, to avoid rusting.

ASSEMBLY – Various kinds of bearings are assembled in different ways. The assembling of taper roller bearing starts with the assembling of rollers in a metal cage and the inner i.e. cone. Final assembly has two such kind of assembled cones which are held in a cup separated by a spacer (which is used to give the rollers enough space for movement even when they are expanded due to heat and other

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reasons). Further this assembly is greased and then rubber seal is placed on it covering the grease and securing the bearing from dust and other such things. The other kind of bearing assembled is spherical roller bearing. Assembling of such roller starts with the rollers being put into a split brass cage which is further put into the outer race. The complete assembly consists of two split cages. Further the inner race is assembled in the above assembly. Brass cages are used owing to the fact that they are weaker as considered to metal and they would be the first to break in case of any damage to the bearing. Besides, split cages play the roll of a complete cage quite efficiently, and also, bearings weigh less. The other kind of bearing is cylindrical roller bearing. The assembling of such kind of bearing starts with the assembling of a cage, rollers and outer race. The outer race consists of two tracks. And thus, two cages are used. Two inner races with single track are used, one being a plane inner race and other consisting of a lip. The reason for using this combination is the fact that it would be easier to fit on the place of its application.

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TAPER ROLLER BEARING

INTRODUCTION - A taper roller bearing has four main components – cone (the inner race), cup (the outer race), rollers (the rolling element in between the races) and, the cage or the retainer which holds the rollers on their track.

These bearings are so designed that when the construction lines are projected corresponding to the contact surface of rollers and races, they meet at an apex point on the bearing axis.

Taper roller bearing can take both types of loads, radial and axial, which is why they are used in gearboxes, heavy trucks, bevel gears, lathe spindles etc.

ROLLER SECTION – The raw material in order to manufacture is High Carbon Chromium, found in the form of wire. First operation for manufacturing the roller from raw material is performed on Cold Header Machine. Firstly wire is fed from drawing machine to cold heading machine. The function of drawing machine is to feed the wire with uniform cross section and without any bend. In the cold heading machine, a cutting tool called ‘Shear Cutter’ cuts a certain length of the wire and transverse it to the die having tapered hole. A punch strikes that wire and a tapered roller is produced. This way a roller is constructed in two strokes.

HEAT TREATMENT – Heat treatment is an important part of the production of a taper roller bearing. As they bear loads in both axial and radial directions, they require good strength which is given to them by hardening process. Due to heating in hardening furnace, quenching is required which further generates brittleness in the job and to remove this brittleness, tempering is done. Tempering also decreases the internal stresses and increases the flexibility and toughness.

RACE GRINDING – The race grinding is quite similar to that of axle boxes’ grinding. It starts with O.D. grinding, followed by track grinding but there is a major difference in lip grinding which is not done simultaneously with track grinding while in case of axle boxes’ grinding, it is done simultaneously owing to the fact that the angle between the lip and the track plays a major role in these types of bearings. Here the track is grounded 1st of all followed by the lip grinding. It is done this way because qualitatively it is better. It is followed by boring and then honing. Major attractions in this department are the new robotic machines which are just loaded in the start and unloaded in the end of the whole process giving the final product. Also, the product is better finished than the old machines’ products.

ASSEMBLING – The assembling starts with the assembling of rollers in a metal cage and the inner race. The outer is simply put onto the assembled part without press fitting. It is left like this so as the bearing can be fitted on its place of application easily.

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LARGE DIAMETER BEARING

The manufacturing of Large Diameter Bearings (or LDB) follows the same procedure as other roller bearings. The different parts of the bearing are manufactured by other companies on order by NEI Ltd., which further undergo heat treatment similar to that of other bearings. The different parts are than grounded in various machines like HMT but the most important machine is BERTHIEZ which can ground any surface with any angle. It is one of the biggest machines in the plant. Assembling of the LDBs is done according to the requirement. The first bearing that was assembled consisted of three cups, one consisting of two tracks and the other two consisting of single tracks, and two cones, both consisting of two tracks. The cones and cups are separated by cone and cup spacers respectively. The second bearing consisted of three cones, one double track and two single track, and two cups, both double track. The third kind was simple cylindrical roller bearing. The rollers it contained had a hole in which a pin is passed through. This pin has threads on one end. The diameter of this pin is less than the diameter of the hole in the roller, so that when the pin is locked with the cage, the roller can easily move. The pin is locked with the help of threads on the one side while it is welded on the other. The fourth kind was a thrust bearing which had horizontal rollers. The cages used are split cages, the reason being the rollers can be easily fitted inside cages this way rather than the other way. The two parts of the cage are locked with the help of a lock pin. It further consists of two discs, one above and one below the cage.

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TOOL ROOM

The tool room of NEI consists of following machines which are used for making different parts like blocks, splines, shoes and, different other tools –

LATHE – Any job can be turned down with the help of lathe machine. The main parts of a lathe machine are Tailstock, Headstock, Chuck, Spindle, Lathe Bed, Carriage, Lead Screw, Tool post and, Cross slide.

MILLING MACHINE – The milling machine is employed for the processes like jig boring, gear cutting, step milling, angular cutting, keyways, splines, notch, and flat surfaces. All kinds of milling machines are there, i.e. Universal, Vertical and Horizontal Milling Machines.

UNIVERSAL GRINDING MACHINE – This machine is generally used for the purpose of making gauges, forming dust seals, punch, harbour, spindles etc. Ordinary wheel is used for grinding common materials while diamond wheel is used for cutting carbide tools.

SURFACE GRINDING MACHINE – This machine is used for removal of material from the surface of job by rotating a grind wheel against the surface of job.

SHAPER MACHINE – It is generally used for making square, rectangular boxes and, angle cutting. In this operation, the job is fixed while the workhead slides against the job so as to remove the material from its surface.

JIG BORING MACHINE – It is used for precision work. It is used to produce jig. The tool is held in vertical chuck eccentrically. Its least count for angle is 1 inch and for longitudinal distance is of 0.2 inch. The table can be lifted to a maximum distance of 18 inch from the bed of machine.

JIG GRINDING MACHINE – It is used for grinding the bore that is to enlarge. The maximum speed of jig tool is 75000rpm. It rotates at a high speed to grind the bore against the job, which is held against the chuck by clamping arrangement.

CNC LATHE MACHINE – The computer numerical control lathe machine is used for turning operations on a job. It can turn the job with fine quality. In this machine, a program is fed into the machine as per drawing and the job is finally turned down.

DRILLING MACHINE – It is used for drilling holes into the job.

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MAINTENANCE & ELECTRICAL

The name of this section itself suggests that the purpose of this is to maintain the machines in the proper running position. In this section, damaged or broken parts are either repaired or replaced by new ones produced in the shop itself. For this purpose section is equipped with various types of machines. For making any part of machine first blue prints are made and then experienced skilled persons manufacture it on these machines.

The various types of maintenance are as follows –

Preventive maintenance Running breakdown maintenance

PREVENTIVE MAINTENANCE

It is general checking of the machine in which all defects of the machine, due to which it is not running properly, are eliminated.

The following defects of the machine are observed –

1. Cleaning2. Lubrication – Oil level, lubrication line to check and repair, oil line to all points3. Pneumatic system – air filter to be cleaned, lubrication to be checked4. Checking of brakes, slides, gears, belts etc.

RUNNING BREAKDOWN MAINTENANCE

When any machine stops suddenly, it is required to eliminate the defect instantly, and for this purpose running breakdown maintenance is done.

DIESEL GENERATOR

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The electricity used in the entire plant is not taken by RSEB completely but a certain amount is produced in the plant itself with the help of diesel generators. A number of diesel generators are there which are controlled by an electronic panel. This panel controls the amount of electricity generated by the entire number of diesel generators in accordance with the requirement of the plant by controlling the number of generators in operation at a time.

AIR COMPRESSOR

It is one of the major requirements of the plant as almost all the machines work on pneumatic power. A number of air compressors are there which are driven with the help of diesel generators. Several pipelines take this compressed air to different departments which are further connected to the machines.

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RING ROLLING SHOP

In this section, rings are made from steel bars with the help of forging press.

A systematic mechanism of rolling machine is as follows –

5 ton E.O.T. crane for loading

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Bar stand

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Bar plate form

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Bar feeding stand

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Induction furnace

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Forging press

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Rolling mill

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Calibration mill

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A systematic process of rolling machine is as follows-

Raw material

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Induction heating

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Bar cutting

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Upsetting

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Pre punching

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Punching

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Rolling

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Calibration

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