NBC Jaipur spherical roller bearing final report


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NBC Jaipur spherical roller bearing final report

  1. 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 1|Page
  2. 2. Equipment and Steel Mills, Heavy Engineering Plants, Bulldozers, Shovels, Tillers and Thermal Power Plants all across the country. 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. 2|Page
  3. 3. 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 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. 3|Page
  4. 4. 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. 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 4|Page
  5. 5. Electric Motors & Pumps:Crompton Greaves G.E. Motors Kirloskar Electric NGEF MICO Fans: Bajaj Electricals Crompton Greaves 1.5. Manufacturing FacilitiesNBC has manufacturing facilities at Jaipur (established in 1946), Newai (established in 1980) and Manesar (established in 2006). A fourth plant, a green field project, at Savli 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 Newai (Gunsi) Plant Manesar Plant 1.5.1. Newai (Gunsi) PlantEstablished 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 & postprocess 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. 5|Page
  6. 6. Fig1.2: Newai (Gunsi) plant 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. Fig1.3: Manesar Plant 6|Page
  7. 7. 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. The plant at Jaipur includesi. Ball Bearing ii. Precision Ball Making iii. Tapered Roller Bearing iv. Railway Bearing v. Research & Development vi. Large diameter bearings vii. SAP-ERP 2.2. Ball BearingThe 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 7|Page
  8. 8. Radial ball bearing Angular Contact Bearing Self-Aligning Two-Row Ball Bearing (a) (b) (c) Fig. 2.1 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, selfaligning 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 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 8|Page
  9. 9. 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. 2.2 Steel Balls 9|Page
  10. 10. 2.4. Tapered roller bearing Type of Tapered Roller Bearing a. Single Row Tapered Roller Bearing b. Double Row Tapered Roller Bearing Single Row Tapered Roller Bearing (a) Double Row Tapered Roller Bearing (b) Fig 2.3 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 10 | P a g e
  11. 11. 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 modernisation 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 Fig 2.4 Axle Boxes 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. 11 | P a g e
  12. 12. 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 Railway The development of completely indigenise axle boxes and bearings for the high speed Rajdhani Locomotive and the Yogoslavia and Egyptian Railway Wagons are the highlights of the design capabilities at NEI. 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 Cartridge Tapered Roller Bearing Spherical Roller Bearing (a) Fig 2.5 Railway Bearings 12 | P a g e (b)
  13. 13. 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 indigenise 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 1.2acres. 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 13 | P a g e
  14. 14. centre. 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. 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. By use of this Package, our processes now conform to World Class best practices. 14 | P a g e
  15. 15. Chapter 3 Railway Bearing Department (Spherical Roller Bearing) 3.1. Introduction I did my training at Railway Baring Department (Spherical Roller Bearing) .This division is spread over covered area of 4,855 Sq. Meters. 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 .Spherical roller bearing has bore (minimum) 40 mm and outer diameter (maximum) 420 mm. These bearings are used by Indian Railway in all zones in the country as original equipment as well as in other countries such as U.S., China, and Indonesia. 3.2. Spherical Roller Bearing A spherical bearing is a bearing that permits angular rotation about a central point in two orthogonal directions (usually within a specified angular limit based on the bearing geometry). Typically these bearings support a rotating shaft in the [bore] of the inner ring that must move not only rotationally, but also at an angle. Spherical Roller bearings for passenger coach applications are especially important and require extremely high levels of performance, durability and reliability. In order to achieve these high levels, NEI (NBC) performs strict inspection and quality control at every stage of design, and production, from selection of material to the processing technology used for manufacturing the bearings. Spherical roller bearings have a large capacity for radial loads, axial loads in either direction, and complex loads. They are suited for the applications such as railways rolling stocks where vibrations and shock loads are encountered. All NBC spherical roller bearing are fitted with machined brass cages. Brass is the most preferred cage 15 | P a g e
  16. 16. material for bearing used in railways all over the world. NBC spherical roller bearings for Meter Gauge and Broad gauge passenger coaches have symmetrical roller design. Where as in case of bearing used in Broad Gauge EMU, rollers are of asymmetric design. Fig3.1: Spherical Roller Bearing 3.3. Bearing materials. The functional performance and endurance of a dimensionally perfect bearing with ideal internal geometries and surfaces, correct mountings, and professional operating conditions are significantly influenced by characteristics of its material. The major criteria to be considered for the satisfactory performance of bearing including material selection and processing with resultant physical properties. Let’s discuss material selection for spherical roller bearing at NBC – Bearing contains varying amount of carbon, iron, chromium, manganese, phosphorus, sulphur, silicon etc. Each of these elements plays a role in making final steel suitable for bearings. Chromium and carbon allows deep hardening. The combination of chromium, carbon & iron helps to minimize failure. As they increase the surface resistance to abrasion & wear increase. In short, proper 16 | P a g e
  17. 17. combination of all these elements make final bearing steel which is tough under shocks, heavy loads & hard enough to withstand fatigue. Generally bearings are made from bars. But now a day, many manufacturers are making bearings by forging rings. The latest techniques adopted recently are the “Vacuum Processing”. The bearing steel is made through vacuum processing, which assists rod to be clean & free from defects & give substantially larger bearing life. Table 3.1 Contents of impurities in a Raw material ELEMENT AMOUNT Manganese 0.25 to 0.35 Silicon 0.025 to 0.35 Sulphur 0.025 max. Phosphorus 0.025 max. Nickel 0.025 max. Copper 0.35 max. Molybdenum 0.10 max. 3.3.1. Raw material for outer ring, inner ring and cages As railway bearing is included in three sections Roller Bearing & Axle Boxes Spherical Roller Bearing Cartridge Tapered Roller Bearing. 17 | P a g e
  18. 18. A spherical roller bearing contains the following partsMain parts of Spherical Roller Bearings are follows(i) Races (outer and inner) (ii) Rollers (iii) Cage The demand on the steel industry to provide higher quality alloy steels promoted the development of the cold charges in the basic material-lined, electric arc furnaces. These furnaces let higher-and lower grade alloy scarps be mixed with plain carbon scarp; economical operation and product quality are achieved through proper selection and weight control of these materials. Knowing the exactly chemistry of scarp charge reduce the consumption of more costly alloys that are added to the melt and minimizes the introduction of undesirable tramp alloying elements. A variety of steel and brasses are used for different components for bearings depending upon the properties required in the final product. Table 3.2 Materials of Different components of a Bearing Balls Ni-Cr Steel wire Rollers High Carbon chrome steel rods Races High carbon steel Cage Brass and mild steel NBC was the first one in India who made the cartridge tapered roller bearing with the help of BRENCO Incorporated of USA. 18 | P a g e
  19. 19. 3.4 Raw material suppliers These are the industries which supply the forged raw material to NBCa) Ajanta turnings b) Balaji engineering c) Keshav engineering d) Microtech engineering e) Microtech rollers The raw material first come in the inspection room and the following parts inspectsa) Turned finish inner ring b) Turned finish outer ring c) Cage or retainer d) Semi finish/Finish rollers Parameters that need to be check: For outer ringa) Width size b) ID(Track Size) c) ID roundness d) OD Size e) OD roundness f) Eccentricity (Bore to OD) g) Surface defects- free from damage, tool mark, black spot, rust, roughness, burr etc. h) Oiling For inner ring19 | P a g e
  20. 20. a) Width size b) Bore c) Undercut size d) Oil groove size e) Surface defects f) OD size g) For SEMI-FINISH/FINISH ROLLERa) OD size b) OD Ovality c) OD Taper d) Length e) Recess Depth f) Surface Roughness g) Radius of large end h) Radius of small end i) Hardness j) Oiling For RETAINERa) Total width b) Small bore diameter c) Pocket length d) OD size at top e) Sheet thickness at bore f) Visual inspection g) No. of pockets 20 | P a g e
  21. 21. 3.5. Manufacturing processes of spherical roller 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: 3.2 Flow diagram of material flow in industry Before going to discuss various dept. in railway division we will go through the bearing material, which we are using in NBC. 21 | P a g e
  22. 22. 3.6. 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 and (vi) Stress reliving. Figure: 3.3 Heat treatment sequence 22 | P a g e
  23. 23. Let’s discusses each process with respect to these parts for simplicity of understanding Fig: 3.4 Flow diagram of heating sequence of spherical bearings 3.7. 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. 23 | P a g e
  24. 24. 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 3.5 Rotary hearth furnace 3.8. 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. 24 | P a g e
  25. 25. 3.9. QuenchingQuenching 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 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. 3.10 TamperingMartensite 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. 25 | P a g e
  26. 26. Fig :3.6 Tempering furnace 3.11. 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 causes26 | P a g e
  27. 27. a) Manufacturing Fault b) Furnace temperature fault c) Tampering fault Fig: 3.7 Rockwell hardness test setup 3.12. 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 27 | P a g e
  28. 28. in N.E.I. Ltd. HOCUT B-60 oil is used. The objectives of cooling is arei. In grinding operations, due to contact of grinding wheel and job they become hot so cooling is necessary. ii. The chip, which is produced by grinding also, flows away. 3.12.1 Operational step to grind Inner race: Fig3.8: process sequence (a) O.D. grindingOD is the circumferential surface of the outer race of the bearing. The OD should be surface finished since the bearing has to be assembled in machine. It is obtain in an OD grinding machine. In this machine the outer race is rotated between two grinding wheel. The outer race is passed in machine three times to get highly finished as follows: 1. Rough1 2. Rough2 3. Fine finish (b) Face grinding28 | P a g e
  29. 29. After hardening process the first of grinding is face grinding and this process is done on facing wheel grinding machine by manual feeding of cup and cone. Facing wheel grinding machine grind the face of races at an average speed of 225 races per hour with maximum capacity of 550 races per hour. After facing inspection of dimension also checked to ensure to quality of grinded face. (c)Flange grindingThe flange should be surface finished since the bearing has to be assembled in machine. It is obtain in the flange grinding machine. In this machine one grinding stone is used to cut and grind the flange portion of cone. NC Mode - AUTO Feed Mode - AUTO Override - 120% (used to change machine speed.) Tool movement during grinding is in all three dimensional axes i.e. X, Y, Z axis. (d) Bore grinding- Bore is the inner circumferential surface of the bearing. The bore should be surface finished since the bearing has to be assembled in machine. It is obtain in the bore grinding machine. In this machine the grinding stone is moved in X and Y axis. Size Limit : +4 µm to -4 µm. TOOL movement during grinding is in only two dimensional axes i.e. X, Z axis. (e) Honing machine (super finishing) 29 | P a g e
  30. 30. Honing is an abrasive machining process that produces a precision surface on a metal work piece by scrubbing an abrasive stone against it along a controlled path. Honing is primarily used to improve the geometric form of a surface, but may also improve the surface texture. 3.12.2. Operation steps to outer race grinding Fig: 13.9 Process sequences for outer race grinding (a) Face grindingFacing of outer ring(cup) also takes place between two facing wheel, out of which one wheel is hard and one wheel is soft. Soft wheel used to take into account wear resistance of hard wheel. After facing inspection takes place with the tolerance of 40 micrometers. Flange width also checked with the tolerance of 15 micrometers (b) Rail grindingTrack is the path on which rollers will move so track of the cup should be grinded properly. So that rollers will move smoothly. 30 | P a g e
  31. 31. Fig: 3.10 Face grinding (c) Honing machine (cup super finishing) As rollers will move on the track so the track surface should be super finished so the rollers will move smoothly. For this purpose honing is done. Now Cup & Cone are ready to send assembly section. They reached assembly section via conveyor. 3.12.3 Operational step in grinding of roller Fig: 3.11 Rollers of spherical bearing 31 | P a g e
  32. 32. Face Grinding Body Grinding Fig: 3.12 Process sequence for grinding of rollers (a) Face GrindingThe face grinding is done after centerless grinding of rollers. Specially made machines used for face grinding. Fig: 3.13 Face grinding of roller (b) Body GrindingBody grinding of spherical rollers is done by specific grinding wheels made for ths operation. Fig: 3.14 Body grinding of rollers 32 | P a g e
  33. 33. (c) Roller super finishing (honing)Mostly one or two stage super finishing machines are used for rollers. The rollers are supported and driven by control wheels. The stone oscillates across the O.D. Fig: 3.15 Roller super finishing 3.13. 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. 33 | P a g e
  34. 34. Fig 3.16 Elements after assembly of spherical bearings 3.14. Maintenance and inspection section 3.14.1 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. 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, 34 | P a g e
  35. 35. vi. MILLING m/c, vii. Universal type, viii. Vertical and Common type, Plain Milling m/c 3.14.2. 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 35 | P a g e
  36. 36. Chapter 4 Learning and Suggestions 4.1. LearningThis training is very fruitful to me. I got immense knowledge of the industry environment as I worked in the Taper Roller Bearing department. Besides that outcomes of the training are pointed out beneath- 4.1.1. Effect of quenching mediumWe are using oil in quenching process but we can also use water, Brine solution or air for quenching purpose. As we know that water has high thermal conductivity and air has the least. So if we use water then cooling of the austenite steel will be very fast and due to this crack will be formed on the surface of the steel or material. If we use air that it will not remove the heat fast because it has low thermal conductivity and it will not serve the purpose. 4.1.2. Rockwell hardness test processBefore and after tampering to check the difference in hardness of bearing races that comes in tampering process Rockwell Hardness Test is being used. The following steps are to check the hardnessTable:4.1 According to material/job, we select the load indenter and scaleMaterial Load Indenter Scale Hard job 150 kg Diamond C (Blake) Soft job 100 kg Ball (HCS) B (Red) 36 | P a g e
  37. 37. 1. Set the polished job (by Mb paper) and apply the load by hand lever 2. Hold the load for 10 seconds 3. Release the lever and note the scale reading Note: The range of hardening of standard piece should lies between +1.5 to 1.5 4.1.3 Why material is demagnetized in Assembly section? As we have noticed that material is demagnetized in the assembly section because bearings will be set at a place where they will rotate and we know if a magnet will rotate then it will produce electric field. So it may hamper the other activities of the system. In machines it will tend to attract the machine parts. 4.1.4 How wastage reduced? To reduce the wastage NBC come on a solution with the help of NTN Corporation. They recognized six type of waste(a) Over ProductionThey produce according to demand of customers. It helps to reduce the waste & scrape. (b)WaitingProcess which takes maximum time, identify that process (bottle neck process) and try to reduce the process time to reduce the idle time of other processes which depends on that. (c)Transportation- 37 | P a g e
  38. 38. Try to minimize the distance between raw material and distance. This will save the worker’s time and money and productivity will be increased. To do this a new process can be stabilized or we can change the layout. (d)InventoryRaw material should not be more than the demand. This stops the money in terms of inventory. (e)MotionCause of this- not placing tools at their proper place, it effects the motion of worker. So there is loss of worker time and loss of machine production. For this we should apply the work standard and design the work table according to need. (f)Re-workCause- if product is not in proper size than there is need to again work on that. This effects the loss of money, loss of worker and loss in production. For this we need to understand the root of problem and try to make product correct in first time. 4.2 Flaking of rollers Fig:4.1 Flaking of rollers 38 | P a g e
  39. 39. Table:4.2 Causes and corrective of flaking Causes Corrective Excessive loads, fatigue life, improper handling Improper mounting Insufficient precision of journal or housing Insufficient clearance Contamination, Rusting Find the cause of heavy, load Softening due to abnormal temperature rise Check internal clearance, regularly Improve precision of journal and housing Improve operating conditions Improve method of assembly and handling Check grease and greasing method 4.3 Comparisons between NBC Bearing and Bajaj BearingTable:4.3 Comparison between NBC Bearing and Bajaj Bearing Type Stake NBC Bearing 11% Bajaj Bearing 3.7% Turnover(2012-13) Rs. 1326 crores Rs. 204 crores Quantity Range 45.6 Million Bearings per annum 6mm bore to 1300 mmOD 7.592 Million Bearings per annum 11mm bore to 95mm OD Quality(Rejection) 1 PPM 6PPM Customers More than 34 big industries 12 industries in India and 21 and 21 countries other countries The comparison between NBC Bearing and Bajaj Bearing show that NBC bearings is better than Bajaj Bearings in quantity wise and quality wise. 39 | P a g e
  40. 40. Chapter 5 Conclusion and Discussion 5.1. Training experience 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. 5.2. About report 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. 5.3 Conclusion 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 bearings mfg. co. 40 | P a g e
  41. 41. How an Industry works. Learning of practical aspects of various dept. (Heat treatment, Grinding) in railway bearings. Got a brief idea about various heat treatment processes along-with their industrial use. Working of conventional machining process (grinding). Industrial applications of all types of grinding and finishing processes. Use of various gauges along-with applications of dial indicators in gauges. How all the maintenance and inspections is done on in line processing or after processing. Various techniques of inspection methods. 41 | P a g e
  42. 42. REFERENCES BHANDARI V.B., Rolling Contact Bearing, Tata McGraw Hill Education Private Limited, Fifth Reprint 2011. RAO P.N, volume 2, Abrasive Processes, Tata McGraw Hill Education Private Limited, Tenth Reprint 2011. RAO P.N, volume 1, Engineering Materials, Tata McGraw Hill Education Private Limited, Second Reprint 2009. RAJVANSHI A.K., Manufacturing Processes, Genius Publications. http://www.nbcbearings.in/nbcpdf/Spherical_Roller_Bearings_catalatue_Fi na.pdf, on 15/06/2013 http://www.nbcbearings.in/nbcpdf/TechnicalCatalogue2012.pdf, on 15/06/2013 http://www.nbcbearings.in/nbcpdf/CTRBM.PDF, on 15/06/2013 http://www.nbcbearings.in/nbcpdf/SRBMM.PDF, on 15/06/2013 http://smartinvestor.business standard.com/BSCMS/PDF/SKF_20080703.pdf 42 | P a g e
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