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Report on dlw varanasi

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Report on dlw varanasi

  1. 1. 1 1. INTRODUCTION TO D.L.W. 1.1.Background Diesel Locomotive Works (DLW) is production unit under the ministry of railways. This was setup in collaboration with American locomotive company (ALCO) USA in 1961 and the first locomotive was rolled out in 1964. This unit produces dieselelectronic locomotives and DG sets for Indian railways and other customers in India and Abroad. Subsequentlya contractfor transfer of technology of4000 HP MicroprocessorControlled AC/AC Freight (GT 46 MAC) /passenger (GT 46 PAC) locomotives and family of710 engines has been signed with electro motive division of general motors of USA for manufacture in DLW. The production of these locomotives has now started and thus DLW is the only manufacturers of Diesel Electric Locomotives with both ALCO and General motors technologies in the world. 1.2. Brief History  Set up in 1961 as a green-field project in technical collaboration with ALCO/USA to Manufacture Diesel Electric Locomotives.  First locomotive rolled out and dedicated to nation in January 1964.  Transfer-of-Technology agreement signed with General Motors/ USA in October1995 to manufacture state-of-the-art high traction AC-AC diesel locomotives.  A flagship company of Indian Railways offering complete range of flanking products in its area of operation.  State-of-the art Design and Manufacturing facility to manufacture more than 150 locomotives per annum with wide range of related products viz. components and sub-assemblies.
  2. 2. 2  Unbeatable trail-blazing track record in providing cost-effective, eco- friendly and reliable solutions to ever-increasing transportation needs for over three decades.  Fully geared to meet specific transportation needs by putting Price-Value- Technology equation perfectly right.  A large base of delighted customers among many countries viz. Sri Lanka, Malaysia, Vietnam, Bangladesh, Tanzania to name a few, bearing testimony to product leadership in its category. 1.3. SALIENT FEATURES Annual production capacity 125 Locomotives Annual turn-over (Rs.) 5000 million Total number of staff 7223 Workshop land 89 Hectares Township area 211 Hectares Covered area in shops 86300 Sq.m Covered area of other service buildings 73700 Sq.m Electrical power requirement (Average maximum demand) 3468 KVA Electrical energy consumption (units/year) 19.8 million Stand by power generation capacity 3000 KW 1.4. PRODUCT OF DLW: DLW is an integrated plant and its manufacturing facilities are flexible in nature. Thesecan be utilized formanufacture of different design oflocomotives of various gauges suiting customer requirements and other products. The product range available is as under:  WDG4 4000 HP AC/AC Freight traffic Locomotive  WDP4 4000 HPAC/AC Broad Gauge High Speed Locomotive
  3. 3. 3  WDG3D 3400 HP AC/AC Broad Gauge Mixed Traffic Micro- Processor Controlled Locomotive  WDM3C 3300 HP AC/DC Broad Gauge Mixed Traffic Locomotive  WDM3A 3100 HP AC/DC Broad Gauge Mixed Traffic Locomotive  WDP3A 3100 HP AC/DC Broad Gauge High Speed Passenger Locomotive  WDG3A 3100 HP AC/DC Broad Gauge Freight Locomotive  WDM2 2600 HP AC/DC Broad Gauge Mixed Traffic Locomotive 1.5. STRATEGIES i. Our Vision: "To be a World class manufacturer of Diesel Electric locomotive" ii. Our Mission:"We shall achieve our vision through Continuous Improvement in the areas of Product Quality, Research and Development, Supplier Partnership, Human Resource Development and Team Work with emphasis on Core Competence Leading to Customer Satisfaction And Business Excellence." iii. Our Quality Policy:"Weare committed to Excellence in all Activities and Total Customer Satisfaction through Continuous Improvement in Quality of Products and Services." iv. Our Quality Philosophy:  Quality is not controlled but produced;  Emphasis is on quality in all organizational processes;  Regular quality audit as per ISO procedures;  Top Management totally committed to quality in all activities;
  4. 4. 4 1.6. QUALITY ASSURANCE Quality has been a crusadein DLW since its very inception. We actively inculcate the primary importance of manufacturing a quality product in all our workmen, supervisors and engineers from the day they join DLW. Each of our workmen is continually trained and re-trained in Quality aspects. Moderninstrumentation and machinery help the workmen in maintaining a high standard of quality. Under ISO 9002 certification scheme, all our jigs and fixtures, tools and gauges are calibrated regularly according to a carefully worked out plan. DLW has a fully equipped Gauge Room for calibration of gauges, and a tool room for checking of jigs and fixtures. Rigorous standards of certification for DLW's vendors, almost all bought-out items are subjected to quality checks and certified by our incoming inspection. Now DLW's Quality thrust has been certified by an internationally accredited ISO certifying body, and DLW is proud owner of ISO 9002 certificate for the entire range of manufacturing activities. 1.7. HUMAN RESOURCES DEVELOPMENT  Battery of highly skilled, motivated and trained man-power treated as the most important organizational asset;  Peoplecentric participative style ofmanagement with societal orientation.  Training forms a continuous part of organizational culture;  Staff trained at General Motors, USA facilities as a part ofnew agreement reached with them;  Management totally committed to healthy Industrial Relations, Staff welfare and Safety;  Excellent industrial safety track record by adopting all round safety measures and conducting regular safety audits; 1.8. EMPLOYEE BENEFITS  DLW is committed to provide best possible staff welfare;
  5. 5. 5  Facilities and competent medical/ paramedical staff to meet any medical emergency;  A well-equipped and modern 90 bed hospital with latest fully self-sufficient, and eco-friendly Township for employees sprawling over 211 hectares, in the vicinity of work-place; 1.9. ENVIRONMENT & OUR SOCIETY At DLW, we firmly believe that no organization can operate in vacuum and therefore, we owe a lot not only to the environment we breath in but also to the society we live in. Our environmental policy and other social goals enshrine this commitment and are reflected in all our activities. 1.10. ENVIRONMENTAL POLICY  We, at Diesel Locomotive Works, Varanasi, while carrying out Chrome- plating and Wastewater Treatment will continually strive to minimize the impact of our activities on the environment. We will minimize the resource consumption and waste generated from these shops to make our surroundings greener and cleaner.  We shall comply with all applicable environmental regulations. 1.12. RESEARCH & DEVELOPMENT  R & D - a Customer centric Activity Committed to Innovation and Continuous Improvement;  Highly skilled Manpower capable of handling complete R&D activities;  A sophisticated design center with modern CAD/ CAE workstations equipped with Unigraphics and Ansys;  Back-up support from RDSO, a centralized R&D organization at corporate level;  Several milestones in the past - an enviable pedigree viz.
  6. 6. 6 R&D strategy aims at absorption of new technology, up-gradation of existing processes, improvement in tool designs and machining facilities, development of new products and special processes for world-class quality - thus helping our customers to succeed.......... 1.13. RECENT MILESTONES & FUTURE PLAN 1.14. MILESTONES ACHIEVED Transfer of technology (TOT) -- An added feather in the cap:-  Agreement with General Motors of USA for technology transfer to manufacture high horse-power GT46MAC 4000HP AC/AC locomotive in India;
  7. 7. 7  Only country outside North-America to have this bleeding edge technology;  Many export/repeat orders complied successfully in recent past and many more in the pipeline; 1.15. FUTURE PLANS Assimilation of GM technology to manufacture their latest 710 series ofdiesel electric locomotives;  To emerge as a globally competitive locomotive manufacturer;  To develop as an export hub for ALCO/ GM locos for Asian market;  To follow an export led growth strategy through continuous improvement;  Cost effectiveness and technology/ product up-gradation as a key to retain global competitiveness by putting price-value-technology equation right. 2. ALLOTED WORKSHOP I have been allotted the following workshops in my four week vocational training. 1. ToolRoom 2. Machine Lab TTC 3. Indian Railway Welding Research Institute 4. Loco Paint Shop
  8. 8. 8 3. Indian Railway Welding Research Institute Welding is a process which produce joining of materials by heating them to suitable temperatures with or without the application of pressure and with or without the use of filler materials. Welding is use for making permanent joint. It is use in the manufacturing of automobile bodies, aircraft frame, machine frame, railway wagons, general repair works, boiler etc. 3.1 TYPE OF WELDING USE IN D.L.W 3.1.1 Shielded Metal Arc Welding [ 𝐒𝐌𝐀𝐖] Shielded metal arc welding (SMAW), also known as manual metal arc welding (MMA or MMAW), flux shielded arc welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode covered with a flux to lay the weld. Fig. 3.1.1 (a) Operation of SMAW An electric current, in the form of either alternating current or direct current from a welding power supply, is used to form an electric arc between the electrode and the metals to be joined. The work piece and the electrode melts forming the weld pool that cools to form a joint. As the weld is laid, the flux coating of the electrode disintegrates, giving off vapours that serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination.
  9. 9. 9 Because of the versatility of the process and thesimplicity of its equipment and operation, shielded metal arc welding is one of the world's first and most popular welding processes. It dominates other welding processes in the maintenance and repair industry, and though flux-cored arc welding is growing in popularity, SMAW continues to be used extensively in the construction of heavy steel structures and in industrial fabrication. The process is used primarily to weld iron and steels (including stainless steel) but aluminium, nickel and copper alloys can also be welded with this method. Equipment Shielded metal arc welding equipment typically consists of a constant current welding power supply and an electrode, with an electrode holder, a 'ground' clamp, and welding cables (also known as welding leads) connecting the two. Fig. 3.1.1 (b) System setup Electrode The choice of electrode for SMAW depends on a number of factors, including the weld material, welding position and the desired weld properties. The electrode is coated in a metal mixture called flux, which gives off gases as it decomposesto prevent weld contamination, introduces deoxidizers to purify the weld, causes weld-protecting slag to form, improves the arc stability, and provides alloying elements to improve the weld quality.
  10. 10. 10 Advantages 1. Lower equipment cost than GTAW, FCAW and GMAW. (No bottle, gas hose, flow meter, and trig rig/Wire feeder needed. 2. Quick Change from one material to another. 3. The process lends itself to welding in confined spaces and various positions with few problems. 4. Deposition Rates faster than GTAW Manual 5. Easy to move from one location to another. No Wire Feeder and Bottle. 6. Some special electrodes are made for cutting/gouging 7. Requires no outside shielding gas and can be used outdoors in light to medium wind. 8. The ability to bend the electrode and the small space the electrode takes allows the process to be used in comparatively tight spaces. However keep in mind that forsomejobs one of the other processesmayalso work or even work better. The FCAW-Self Shielded process can weld with a very long electrode sickout. Disadvantages 1. Low deposition rate compared to GMAW/FCAW. 2. Filler metal costper weld can be greater due to a low deposition efficiency that can vary greatly with stub length. 3. Production factor is typically lower (Unless welding on various materials) due to rod changes and chipping slag. 4. Needs more hand eye coordination than GMAW/FCAW. 5. Slag must be removed as compared to GTAW/GMAW Application 1. Used to weld carbonsteel, low and high alloy steel, stainless steel, cast iron, and ductile iron. 2. The thickness of the material being welded is bounded on the low end primarily by the skill of the welder, but rarely does it drop below 1.5 mm (0.06 in). 3. SMAW can be used in any position
  11. 11. 11 3.1.2 Submerged arc welding [ 𝐒𝐀𝐖] In SAW the welding heat source is an arc - maintained between a consumable electrode and the work piece. The arc and molten metal are "submerged" in a blanket of granular fusible flux. The electrode is continuously fed into the arc and additional flux is distributed in front as the weld head moves along the joint Submerged arc welding (SAW) is a common arc welding process. Submerged arc welding (SAW) is so named because the weld and arc zone are submerged beneath a blanket of flux. The flux material becomes conductive when it is molten, creating a path for the current to pass between the electrode and the work piece. The flux blanket prevents spatterand sparks, while shielding ultraviolet light and fumes that are normally a partofshielded metal arc welding. The flux usually is supplied to the welding head via a small hopper. A collection system gathers the excess flux for reuse. The process uses one or more continuously fed electrodes (wires) to maintain an arc. SAW is known for its ability to depositlarge amounts of metal quickly, consistently, and safely. The basic SAW equipment is a power source, control unit, wire unit, and nozzle. Fig 3.1.2(a) Working principal of SWA
  12. 12. 12 Power and Control On the input side, it is no longer necessaryto use single-phase power only. The new machines can connect to three-phase power and the same power supply used for both. This is achieved simply bymodifying a plug so current and voltage remain stable and consistent. Inverters make it possible to use the same piece of equipment anywhere in the world. State-of-the-art SAW controls are all digital, allowing constant feedback for monitoring and changing voltage, amperage, wire feed speeds, and so forth Digital PLCs are set up to interface with the application selected at the power source, and in some cases one controller can handle any choice of AC, DC CV, or DC CC. Travel Speeds and Consumable Materials The flexibility of the new power sources allows manufacturers to focus on faster travel speeds, which enhance quality in high-deposition welds. 'In the '50s and '60s the tractors were huge. Now they are much smaller and can work faster," Fisher said. One of the concerns with early SAW was variable feed speeds of the tractor. Now tractors equipped with speed control can change speed when the load changes, keeping other variables more constant. Adaptability is still the name of the game, so even modular tractors can be taken apart without tools to be passed through small spaces where they are reassembled to perform necessary operations. These high-end tractors are extremely versatile in what they can do. SAW also makes good of strip cladding, a process that debuted in the 1960s. The consumable is a metal or alloy strip—measuring 0.79 to 4.72 in. wide and about 0.020 in. thick—which is used in place of a common wire electrode. The arc passes between the strip and the work piece, while the flux shields the weld from the atmosphere and the operator from spatter. This is another option to achieve high deposition and eliminate a number of passes. SAW Electrodes • Functions of the electrode: - - Conducts electrical current to the arc - Supplies joint filler material
  13. 13. 13 •Electrodes may consist of :– - solid rod or wire - composite electrode (a metallic sheath encasing metal powders) SAW Fluxes • Functions of the flux - Establish the electrical characteristics of the electrode and arc stability - Controlthe composition and metallurgy of the weld deposit - Supply additional filler material - Control weld bead shape. • Flux constituents - The flux consists ofgranular minerals and metals in the form of fused and crushed or bonded agglomerated particles. SAW Equipment • Power Supply - Constant current orconstant voltage type 100% duty cycle 1000 A output • Wire Feeder - Constant speed (for constant voltage power supplies) or voltage sensing (for constant current power supplies) • Travel & Positioning Device - e.g. weld head crawler or rotary positioner • Flux delivery/recovery system • Process Controls
  14. 14. 14 - Welding current, travel/work piece positioning, wire feed sequencing. SAW Applications • Joining heavy sections in steel, stainless steels - Pressure vessel & piping circumferential & longitudinal seams - Plate girder fabrication - Ship panel subassembly • Surfacing - Multi-wire & strip cladding variants Advantages 1. Molten flux provides very suitable conditions for high current to flow. Great intensities of heat can be generated and kept concentrated to weld thicker sections with deep penetrations. 2. Because of high heat concentration, considerably higher welding speeds can be caused. 3. Because of high heat concentration and high welding speeds weld distortion is much less. 4. High metal deposition rates cane be achieved. Single pass welds can be made in thick plates with normal equipment. 5. Welding is carried out without sparks, smoke, flash or spatter. 6. Weld metal deposit possessesuniformity, good ductility, corrosionresistance and good impact strength. 7. Very neat appearance and smoothweld shapes can be got.
  15. 15. 15 8. The submerged process canbe used for welding in exposed areas with relatively high winds. 9. Practically, no edge preparation is necessary for materials under 12 mm in thickness. Disadvantages 1. Since the operator cannot see the welding being carried out, he cannot judge the progress of welding accurately. Therefore accessories like jigs and fixtures, pointers, light beam focusing devices or roller guides may be used for proper welding at the joint. 2. The flux needs replacing of the same on the joint which is not always possible. 3. The progress is limited to welding in flat position and on the metal more than 4.8 mm thick. In small thicknesses burn through is likely to occur. 4. The process requires edge preparation and accurate fit up on the joint. Otherwise the flux may spill through the gap and arc may burn the work piece edges. 5. Flux is subjected to contamination that may cause weld porosity. 6. Weld metal chemistry is difficult to control. A change in welding variables especially when using alloyed fluxes may affect weld metal composition adversely. 7. Cast iron, Al alloys, Mg alloys, Pb and Zn cannot be welded by this process.
  16. 16. 16 3.1.3 Gas Metal Arc Welding [ 𝐆𝐌𝐀𝐖] GMAW is the most common industrial welding process, preferred for its versatility, speed and the relative ease of adapting the process to robotic automation. Unlike welding processes that do not employ a shielding gas, such as shielded metal arc welding, it is rarely used outdoors or in other areas of air volatility. A related process, flux cored arc welding, often does not use a shielding gas, but instead employs an electrode wire that is hollow and filled with flux. GMAW was soonapplied to steels because it provided faster welding time compared to other welding processes. The cost of inert gas limited its use in steels until several years later, when the use of semi-inert gases such as carbon dioxide became common. Fig3.1.3.(a) working principle of GMAW Equipment To perform gas metal arc welding, the basic necessary equipment is a welding gun, a wire feed unit, a welding power supply, a welding electrode wire, and a shielding gas supply.
  17. 17. 17 Welding gun and wire feed unit The typical GMAW welding gun has a number of key parts—a control switch, a contact tip, a power cable, a gas nozzle, an electrode conduit and liner, and a gas hose. The control switch, or trigger, when pressed by the operator, initiates the wire feed, electric power, and the shielding gas flow, causing an electric arc to bestruck. The contact tip, normally made of copperand sometimes chemically treated to reduce spatter, is connected to the welding power source through the power cable and transmits the electrical energy to the electrode while directing it to the weld area. It must be firmly secured and properly sized, since it must allow the electrode to pass while maintaining electrical contact. On the way to the contact tip, the wire is protected and guided by the electrode conduit and liner, which help prevent buckling and maintain an uninterrupted wire feed. The gas nozzle directs the shielding gas evenly into the welding zone. Inconsistent flow may not adequately protect the weld area. Larger nozzles provide greater shielding gas flow, which is useful for high current welding operations that develop a larger molten weld pool. A gas hose from the tanks of shielding gas supplies the gas to the nozzle. Sometimes, a water hose is also built into the welding gun, cooling the gun in high heat operations. Tool style The top electrode holder is a semiautomatic air-cooled holder. Compressed air circulates through it to maintain moderate temperatures. It is used with lower current levels for welding lap or butt joints. The second most common type of electrode holder is semiautomatic water-cooled, where the only difference is that water takes the place of air. It uses higher current levels for welding T or corner joints. The third typical holder type is a water cooled automatic electrode holder—which is typically used with automated equipment. Power supply Most applications of gas metal arc welding use a constant voltage power supply. As a result, any change in arc length (which is directly related to voltage) results in a large change in heat input and current. A shorter arc length causes a much greater heat input, which makes the wire electrode melt more quickly and thereby restore the original arc length. This helps operators keep the arc length consistenteven when manually welding with hand-held welding guns. To achieve a similar effect, sometimes a constant current power source is used in combination with an arc voltage-controlled wire feed unit. In this case, a change in arc length makes the wire feed rate adjust to maintain a relatively constant arc
  18. 18. 18 length. In rare circumstances, a constantcurrent powersourceand a constantwire feed rate unit might be coupled, especially for the welding of metals with high thermal conductivities, such as aluminum. This grants the operator additional control over the heat input into the weld, but requires significant skill to perform successfully. Electrode Electrode selection is based primarily on the composition of the metal being welded, the process variation being used, joint design and the material surface conditions. Electrode selection greatly influences the mechanical properties of the weld and is a key factor of weld quality. In general the finished weld metal should have mechanical properties similar to those of the base material with no defects such as discontinuities, entrained contaminants or porositywithin the weld. To achieve these goals awide variety ofelectrodes exist. All commercially available electrodes contain deoxidizing metals such as silicon, manganese, titanium and aluminum in small percentages to help prevent oxygen porosity. Some contain denigrating metals such as titanium and zirconium to avoid nitrogen porosity. Depending onthe process variation and base material being welded the diameters of the electrodes used in GMAW typically range from 0.7 to 2.4 mm (0.028 – 0.095 in) but can be as large as 4 mm (0.16 in). The smallest electrodes, generally up to 1.14 mm (0.045 in) are associated with the short-circuiting metal transfer process, while the most common spray-transfer process mode electrodes are usually at least 0.9 mm (0.035 in). Shielding gas Shielding gases are necessary for gas metal arc welding to protect the welding area from atmospheric gases such as nitrogen and oxygen, which can cause fusion defects, porosity, and weld metal embrittlement if they come in contactwith the electrode, the arc, orthe welding metal. This problem is common to all arc welding processes; for example, in the older Shielded-Metal Arc Welding process (SMAW), theelectrode is coated with a solid flux which evolves a protective cloud of carbon dioxide when melted by the arc. In GMAW, however, the electrode wire does nothave a flux coating, and a separate shielding gas is employed to protect the weld. This eliminates slag, the hard residue from the flux that builds up after welding and must be chipped off to reveal the completed weld.
  19. 19. 19 Operation Formostofits applications gas metal arc welding is a fairly simple welding process to learn requiring no more than a week or two to master basic welding technique. Even when welding is performed by well-trained operators weld quality canfluctuate since it depends onanumber ofexternal factors. All GMAW is dangerous, though perhaps less so than some other welding methods, such as shielded metal arc welding. Advantages As mentioned above, the GMAW process is possible the most widely used process in the United States. This is due to several advantages. Below are listed several of these advantages: 1. Low costequipment – a hobby welder can get a welding machine from a reputable manufacturer suchas Lincoln Electric or ITW for less than $600. Add a few dollars for shielding gas and mig wire and you are welding for less than $700. 2. Low cost consumables – out of all the process the consumables for mig welding have the lowest cost. You can purchase mig wire from a big box store for less than $3 per pound. Or you can go to a local industrial distributor and get it for closer to $2 per pound. 3. High depositionrates – especially when compared to stick welding. With the GMAW process you can deposit up to nearly 10 pounds per hour (deposited weld metal).
  20. 20. 20 4. Low hydrogen deposits – since solid does not pick up moisture like flux- cored wires and stick electrodes it consistently deposits welds with low levels of diffusible hydrogen. You can learn more about why this is important by reading “WHY WELDS CRACK” 5. Can weld almost all metals – by simply changing your filler wire and at times the shielding gas you can weld from carbon steel, to stainless steel, to nickel alloys and aluminum. 6. Low levels of spatter – low spatter can be achieved by selecting the right mode of metal transfer. Spray and pulse welding can provide this benefit. To learn more read “MODES OF METAL TRANSFER” 7. Unlimited thickness – this process allows for welding light gage material and up to unlimited thickness by using multiple passes. Higher amperages and proper joint configuration are needed to weld. 8. Easy to learn – unlike tig welding or stick welding, mig welding is easy to learn. 9. Little cleanup – since mig welding is a slagless process itdoes notrequire chipping slag, cleaning up flux or discarding unused stick stubs. 10.High electrode efficiencies– the GMAW process provides efficiencies of 93-97%. This means that if you buy 100 pounds of mig wire you will be deposition 93 to 97 pounds of weld metal. A process like SMAW (stick welding) has electrode efficiencies of around 65%. This is due to loss due to spatter, slag, and not consuming the entire electrode. 11.Input voltages – If you have electric service you can weld. Smaller machines can run on 115 volt input. These machines are limited to about ¼” welding thickness. Some of the newer industrial machines are capable or running anywhere from 208 to 575 input voltage on either single or three-phase circuits. Most mig welding machines can also run off of portable generators. Limitations 1. Sensitive to contaminants – the process can only handle low to moderate levels of surface contaminants such as rust, mill scale, dirt, oil and paint. All these have potential to create problems such as porosity, incomplete fusion, bad bead appearance and even cracking.
  21. 21. 21 2. Portability – moving the welding equipment may not be that tough, but you also have to handle the high pressure cylinders that contain the shielding gas. Proper care must be taken. 3. Sensitive to wind – the shielding gas used for mig welding can easily be blown away when welding outdoors. Even inside, a fan or a wind draft of as low as 5mph can be enough to cause porosity. 4. Lack of fusion – due to the ability to weld at low currents this process has the potential for lack of fusion when running in short circuit mode. Make sure you always use the correct procedure for the thickness of material you are welding. There is a reason why the American Welding Society does not have pre-qualified procedures using the short-circuit mode of metal transfer. 5. Open arc process – as with most welding process, GMAW exhibits an open arc. Proper care must be taking to shield the welder and bystanders from the harmful UV rays.
  22. 22. 22 3.1.4 Flux-cored arc welding (FCAW or FCA) Flux-cored arc welding (FCAW or FCA) is a semi-automatic or automatic welding process. FCAW requires a continuously-fed consumable tubular electrode containing a flux and a constant-voltage or, less commonly, a constant-current welding power supply. An externally supplied shielding gas is sometimes used, but often the flux itself is relied upon to generate the necessary protection from the atmosphere, producing both gaseous protection and liquid slag protecting the weld. The process is widely used in construction because of its high welding speed and portability. FCAW was first developed in the early 1950s as an alternative to shielded metal arc welding (SMAW). The advantage of FCAW over SMAW is that the use of the stick electrodes used in SMAW is unnecessary. This helped FCAW to overcome many of the restrictions associated with SMAW. Fig 3.1.4 (a) Working principal of FACW Flux Core Arc Welding (FCAW) uses a tubular wire that is filled with a flux. The arc is initiated between the continuous wire electrode and the work piece. The flux, which is contained within the coreof the tubular electrode, melts during welding and shields the weld pool from the atmosphere. Direct current, electrode positive (DCEP) is commonly employed as in the FCAW process. There are two basic process variants; self-shielded FCAW (without shielding gas) and gas shielded FCAW (with shielding gas). The difference in the two is due to different fluxing agents in the consumables, which provide different benefits to the user. Usually, self-shielded FCAW is used in outdoor conditions where wind would blow away a shielding gas. The fluxing agents in self-shielded
  23. 23. 23 FCAW are designed to not only deoxidize the weld pool but also to allow for shielding of the weld pool and metal droplets from the atmosphere. The flux in gas-shielded FCAW provides for de oxidation of the weld pool and, to a smaller degree than in self-shielded FCAW, provides secondary shielding from the atmosphere. The flux is designed to supportthe weld poolfor out-of position welds. This variation of the process is used for increasing productivity of out-of-position welds and for deeper penetration. Process variables  Wire feed speed (and current)  Arc voltage  Electrode extension  Travel speed and angle  Electrode angles  Electrode wire type  Shielding gas composition (if required)  Reverse polarity (Electrode Positive) is used for FCAW Gas-Shielded wire, Straight polarity (Electrode Negative) is used for self-shielded FCAW Fig3.1.4(b) Equipmentof FCAW
  24. 24. 24 Advantages  FCAW may be an "all-position" process with the right filler metals (the consumable electrode)  No shielding gas needed with some wires making it suitable for outdoor welding and/or windy conditions  A high-deposition rate process (speed at which the filler metal is applied) in the 1G/1F/2F  Some "high-speed" (e.g., automotive) applications  As compared to SMAW and GTAW, there is less skill required for operators.  Less preleasing of metal required  Metallurgical benefits from the flux suchas the weld metal being protected initially from external factors until the slag is chipped away Applications  Mild and low alloy steels  Stainless steels  Some high nickel alloys  Some wear facing/surfacing alloys  Porosity chances very low Disadvantages  Melted ContactTip – happens when the contact tip actually contacts the base metal, thereby fusing the two and melting the hole on the end  Irregular wire feed – typically a mechanical problem  Porosity – the gases (specifically those from the flux-core) don’t escape the welded area before the metal hardens, leaving holes in the welded metal  More costly filler material/wire as compared to GMAW  The equipment is less mobile and more costly as compared to SMAW or GTAW.  The amount of smoke generated can far exceed that of SMAW, GMAW, or GTAW.  Changing filler metals requires changing an entire spool. This can beslow and difficult as compared to changing filler metal for SMAW or GTAW.
  25. 25. 25 4. Machine Lab TTC A machine shopis a room, building, orcompanywhere machining is done. In machine shop, machinists use machine tools and cutting tools to make parts, usually of metal or plastic (but sometimes of other materials such as glass or wood). In which the generally lathe machine are used for this purpose. In this section all kinds of machining is done to obtain the correctsize and shape of the job. Besides, machining of steel job, Aluminum-plates are also machined here. Machining is other performed manually or on automatic machines. Machines are two types… 1. AUTOMATIC. 2. MANUALLY. There are three types of automatic machine. 1. Numerical control. 2. Computer numerical control. 3. Direct numerical controlmachine. NUMERICAL CONTROL-Themachining parameter are feed from the control panel by pushing buttons .The job is machined according to the parameter There are N.C. boring machine in this shop. COMPUTER NUMERICAL CONTROL- In this machine all the data corresponding to the initial work piece to the final product is feed into the computer. All the process required in the order of action is fed with the help of programmer .In this machine one, has to just fix the job is to the chuck. All the other process is done automatically. This is the machine use for large scale production. In this shop there is one CNC chucker turret Lathe machine. DIRECT NUMERICAL CONTROL-This machine is controlled by installing a control room away from the work place .These machine are D.N.C. machine. These are fully automated .The machine shop is divided into different divisions to the task accomplished .Theses sections are- 1. Capstan and turret lathe section. 2. Milling section. 3. Drilling section.
  26. 26. 26 4. Central lathe section. 5. Heavy machine section. Lathes Lathes are very versatile. They are usually used to machine (turn) round (cylindrical) parts, butcanalso producemany unique and irregular shapes.Alathe can drill, ream, turn, knurl, cut and shape cylindrical parts. The type of machine in the UCR Mechanical Engineering Machine Shop is a manual lathe, also known as a tool room lathe. Although there are several other types of LATHES, this document will focus only on the manual lathe. They are also known as tool room lathes and/or engine lathes. Normally, a part is held in a collet or lathe chuck and a cutting tool is held in a tool post. The lathe is switched on and the part begins to rotate. The cutting tool is then brought to the rotating part and removes material. Fig. 4 (a) Lathe Machine BASIC MACHINE PARTS  SPINDLE LOCK KNOB For keeping the spindle from rotation when tightening or loosening collets.
  27. 27. 27  TAILSTOCK For accurately holding the tailstock spindle.  TAILSTOCK HAND WHEEL Formoving the tailstock spindle toward or away from the workpiece.  TAILSTOCK SPINDLE For holding drill chucks or lathe centers in the tailstock.  SPINDLE SPEED DISPLAY Shows the spindle speed in Rotations Per Minute (RPMs).  SPINDLE SPEED KNOB For adjusting the speed of the lathe spindle.  CARRIAGE Moves the tool post, cross slide toward or away from the chuck.  EMERGENCYSTOP SWITCH For shutting off the spindle rotation and feeds in caseof an emergency!  COLLET CHUCK For holding small diameter work pieces in the spindle of the lathe.  TOOL POST For holding and quickly changing between different ToolHolders.  TOOL HOLDER Forholding lathe bits and other lathe cutting tools.  COMPOUND SLIDE HAND WHEEL Formanually feeding cutting tools at an angle to the spindle.  CROSS SLIDE HAND WHEEL For manually feeding cutting tools across the spindle (the X axis).
  28. 28. 28  CARRIAGE HAND WHEEL For manually feeding cutting tools in line with the spindle (the Z axis).  CROSS SLIDE FEED LEVER For turning the auto feed for the cross slide on and off.  CARRIAGE FEED LEVER Forturning the auto feed for the carriage on and off.  SPINDLE ON/OFF & DIR. LEVER For turning the spindle on or off and for setting the rotation direction.  FEED DIRECTIONKNOB To determine the direction of the carriage or cross slide auto feed. Fig . 4 (b) Lathe Machine component
  29. 29. 29 USING THE MACHINE 1. Three important elements. In order to get an efficient process, good surface finish and correct geometry on the lathe, it is important to adjust the rotating speed (RPM), a cutting depth and a feed speed. Please note that these important elements cannot be decided easily, because these suitable values are quite different for each material. • ROTATION SPEED It is the number of rotations per minute (rpm) of the chuck or collet. When the rotating speed is high, higher removal rates are possible. But when too high, too much friction could be generated. However, since a little operation mistakes may lead to the serious accident, it is better to set lower rotating speed at the first stage. • CUTTING DEPTH The cutting depth of the tool affects to the processing speed and the roughness of surface. When the cutting depth is big, the processing speed becomes quick, but the surface temperature becomes high, and it has rough surface. Taking off too much material can break the tool or your workpiece. If you do not know a suitable cutting depth, it is better to set to small value. Always remove a very small amount of material on your final pass to assure a good surface finish. • FEED SPEED The feed speed of the tool also affects to the processing speed and the roughness of surface. When the feed is high, you can remove a lot of material quickly. When the feed is low, the surface improves. There are automatic feeds on these machines that can move the feed handles for you at a very accurate feed. These auto feeds maintain a consultant speed and result in nicer finishes. A beginner must always use the manual mode, until they have enough experience. A user should hold the handle ofthe automatic feed until the operation is complete and never walk away. Serious accidents may occur if the tool bit or any part of the post or the cross slides touch the collet or chuck!
  30. 30. 30 2. Common lathe cutting tools. Always use the correctand properly sharpened toolfor the job. Dull tools lead to bad surface finishes, out of tolerance parts and potentially a hazard situation. Below are the three most common types of lathe tools. • THE LATHE BIT The image above shows the most common lathe cutting tools, they are called lathe bits. These can cut outside surfaces and edges. There are versions that consistof a piece of carbide brazed onto a rectangular steel bar. The ones in the above image are called “insert lathe tools.” It is because they have a carbide insert that can be replaced or rotated when they become dull. This is ideal for those that have little or no experience in grinding their own tools. • THE CUT OFF TOOL This tool(shown above) is also called a “parting tool.” It is primarily used for cutting off (aka, parting) the work piece and making outside grooves. This tool can only cut “across” the part in one direction (along the X axis). • THE BORING BAR This tool (shown above) is mainly used to make diametrical (round) holes of any size and depth. Normally used to cut at an inside surface. It can make a hole that is much bigger and more accurate than a regular drill. The other big advantage is that a boring bar canmake irregular diameter holes with flat bottoms. Drills and reamers are only available in “standard” sizes, but a boring bar does not have that limitation. In mostcases, there needs to be an existing hole to fit the boring bar. This hole can be produced with the use of a regular drill bit. 3. Clamping work-pieces using a Lathe Chuck. A chuck is directly attached to the drive mechanism (spindle) of the lathe and rotates at variable speeds up to as much as 1000 rpm on this machine. A 3 or 6 jaw chuck has the ability to hold a wide range of cylindrical parts from .250” diameter, all the way up to 8” diameter. To start, the operator clamps the piece of metal to be turned in the chuck. Depending on the size (diameter and/or length) of the part, will determine how much of it will need to be clamped in the chuck. Thesechucks are very accurate, but pieces of metal are not always perfectly straight and level. So it is recommended that you use a dial indicator to check the concentricity your work
  31. 31. 31 piece in relationship to the machine. This can be doneby placing the indicator on top of the tool post with the dial stem touching the part and with the machine turned OFF, rotating the chuck by hand. Depending on the required precision, it is important to check the trueness of the part to within one or two thousands of an inch. Once you are sure that the part is true, tighten the chuck as tight as necessary to hold the part without damaging the clamping surface. This is done by placing the "chuck key" in the key receptacle on the side of the chuck and turning it clockwise. NEVER LEAVE THE KEY IN THE CHUCK!!! Place the chuck key on the workbench, away from all moving parts. If the key is left in and the machine started, serious bodily harm will result! Check once more for “true” if the precision is necessary. Before even starting the machine, spin the chuck by hand to make sure it clears the carriage, cross slide, tools, tool post and/or all other parts of the machine! There are also 4 jaw chucks where each jaw can beadjusted independently, these are for off-center lathe work and require special training. Consult the shop supervisor if your parts need this tool. The spinning jaws on a chuck are very dangerous. At certain speeds, the jaws become an invisible blur! In a noisy environment, a spinning chuck may not appear to be spinning. Always be aware ofthe jaws as you are working on the lathe! Keep your hands, body and cutting tools well away from the chuck at all times! 4. Clamping work-pieces using the collet chuck. A collet chuck takes the place of a 3, 4/ or 6 jaw chuck. It uses collets to hold diameters ranging from .125” to 1.313”. Since it relies on collets and has no spinning jaws, it is more accurate and safer way to hold your work. Make sure that the diameter of your work piece matches the size of the collet within (+/-) .015” Any larger variations and the work piece could slip or the collet could be damaged! Make sure the spindle is OFF and not rotating before inserting orremoving collets or work pieces! Also, you should move the tailstock and carriage/saddle away from the collet chuck. The collet is inserted into the collet chuckby aligning the “key”. You have done this correctly when the collet slips almost completely into the collet chuck. Place your work piece into the collet (at least 1” in for most diameters!). Then tighten the collet bypressing and holding the spindle lock knob
  32. 32. 32 and simultaneously rotating the collet chuck wheel away from you. To loosen the collet, press and hold the spindle lock knob and simultaneously rotate the collet chuck wheel toward you. It might take several rotations to release your part. 5. Tool post and cutting tool set-up. The toolpostis where the cutting tool and holder will be located. The tool postuses a dovetail design to enable a user to pre-set a number of tools for easy and accurate changes between cutting tools. The tool post is permanently mounted to the machine, but canbe move and rotated. The toolholders have knob on top to quickly adjust cutting tool heights. Forsafe and efficient cutting, the tip ofthe tool must be located directly on the center of the part in the chuck! Too high and the base of the tool will pushon the part. This may damage your work piece or break the cutting tool. If the tool is set too low, the tip of the tool will tend to gouge and/or cut too deep. It will also leave an undesirable “nub” when you reach the center of the work piece. A quick trick forsetting the toolheight is to gently squeeze a 6” metal scale between the cutting tool and your work piece with the machine OFF and spindle stopped. Have the shop supervisor show you how to do this properly and easily. This technique will get you very close to the ideal tool cutting height with most lathe tools. 6. Moving the carriage and cross slide. The carriage moves along the “ways” toward and away from the chuck(the Z axis). The cross slide moves toward and away from the center or the part (the X axis). The carriage and the cross slide are both moved manually by using hand wheels. The cross slide hand wheel has dials that show DIAMETRICAL distances. Each graduation on the hand wheel indicates .001”of diameter movement of your tool. Movement of the carriage is measure with the use of a dial indicator mounted on the left side of the carriage. It is limited to 2 inches of travel for measurement purposes, but can be set anywhere along the carriage’s travels. In addition, there are two levers on the carriage that turn on the carriage and cross feed “powerfeeds.” One feeds (moves) the carriage at a predetermined speed and the other feeds the cross-slide. There is also a (push/pull) knob that changes the direction of both feed levers! To understand these features, you should test these operations well away from the chuck, at different speeds and
  33. 33. 33 while supervised. This will enable you to get the feel ofthe automated movements of the machine. 7. Compound slide A compound slide is a smaller version of the cross feed with one major difference, it can be set at any angle. It offers a way to turn tapers and cut angles on a lathe. Mostcommonly it is used to cuttapered holes and other conical shapes using a boring bar or lathe bits. There is a degree wheel directly underneath the compound slide that can be set to the specific angle that is needed. There is no “power feed” option and it must be operated manually. 8. Tailstock and its features. The tailstock is located on the opposite end of the lathe from the chuck. It is mounted on the ways of the machine and shares a centerline with the chuck. The tail-stock’s most common use is to drill out the centers of work pieces. Into the tailstock you can insert a drill chuck (that has a compatible “Jacobs Taper”). The tailstock is slid toward the work piece and LOCKED DOWN, leaving about 1” of roombetween the drill and the work piece. The tailstock hand wheel is then used to feed the drill into the work piece. Unlike other machines, the lathe work piece spins and the cutting tool stays still. The other commonuse is to supportlong work pieces (shafts / tubes / rods) with the use of a live center. A live center is a cone shaped object with a Jacobs’s taper adapter that is inserted into the tailstock (like a drill chuck). The cone portion spins on an internal ball bearing mechanism. This is used to fit into a center hole of the work piece to hold it firmly between the tailstock and chuck. It is VERY important to lock down the tailstock and set correct tension with the tailstock hand wheel whenever using the live center. This is done for pieces that are too long to be safely held in just a chuck or collet. Normally, if the length of piece is sticking out more than 5 times the diameter, a live center should be used. For example, if the part is 1” in diameter, it should not stick out more than 5” in length. Again, check with the shop supervisor for guidance! Live centers should not be used when the work piece will be parted with a cut-off tool. DRILLING SECTION Drilling operation is carried out here. A large for the operation .To complete the operation faster a few gauge milling machine are also provides.
  34. 34. 34 Fig. 4 (c) DRILLING MACHINE CENTER LATHE SECTION Heavier lathes are provided in this section. All the lathes have four jaws chuck for better holding centering is done either manually or with the help of universal scriber. All kinds of turning are performed here. Parting off is other major operation done. Fig .4 (d) Centre lathe machine
  35. 35. 35 SHAPER The machine is also called horizontal shaping machine. It works on quick-return mechanism .The arm of shaper reciprocating horizontally. The cutting take place only in the forward stroke. The bed of the machine is fixed and the tool reciprocating. Shaping, Planning, Grooving etc. are performed by this machine. Fig .4 (d) Shaper machine SLOTTER The is vertical shaping machine .The arm reciprocating in the vertical direction .Mostparts are the same as shaper .Slotting is the process thatis carried on this machine . Fig .4(e) Slotter
  37. 37. 37 Fig 5.(b) Thinner THE MAIN PROCESS INVOLVE IN PAINTING – Firstly, Putin is prepared and it gets filled at the places where holes and cracks has been found. Secondly, the primer is put on the bodyand then finally painting is done in order to give the body desire shape. The overhauling of the coaches has been in given time interval it improves the quality of coaches and it also prevents the coaches from break down. The maintenance of coaches is according to time being is done as following- 1. MAIL EXPRESS- 12 MONTHS. 2. PASSENGER- 18 MONTHS. 3. NEWLY COACHES- 24 MONTHS. TYPES OF PAINT 1. Aluminum Paint. 2. Anti-corrosive. 3. Asbestos paint. 4. Bituminous paint. 5. Cellule paint. 6. Cement paint. 7. Distemper. 8. Plastic paint.
  38. 38. 38 9. Graphite paint. 10.Oil paint 11.Silicate paint. 12.Luminous paint. 13.Enamel paint. 14.Emulsion paint.
  39. 39. 39 6.Tool Room A tool room is a room where tools are stored or, in a factory, a space where tools are made and repaired for use throughout the rest of the factory. In engineering and manufacturing, tool room activity is everything related to tool- and-die facilities in contrast to production line activity. Fig 6(a) Maintenance of tools Making, repairing, and storing tools The simplest sense of the word tool room implies merely storage. A broader use of the term includes a space where tools are made, repaired, inventoried (kept track of), and distributed for use throughout the rest of a factory. This extension of sense reflects the development of greater systemization in manufacturing. During the 19th century, there gradually developed the division of labour whereby the people who made, repaired, kept records of, stored, and retrieved tools were not necessarily the same people who used the tools to do the manufacturing work itself. Examples of division of labour had existed in prior centuries, but most manufacturing had been done on a craft basis, where there had been no need for the idea of a tool room separate from the rest of the workshop (or a word to name it).
  40. 40. 40 The simplest sense above can also be conveyed by the word tool crib (sometimes styled tool-crib or toolcrib). Although the word tool room is still sometimes used todayin those simpler senses (and probablyalways will bebecauseofthe obvious correspondence of word to literal meaning), mechanical engineers, toolmakers, and other trained machinists usually use the word in its abstract tool-and-die sense, which is discussed below. This restriction of sense is aided by using another word (such as tool crib) to refer to the simpler, concrete senses. Tool Room (TR) is the industrial set-up where the specialized tools, dies, moulds, jigs, fixtures are designed and manufactured. These tools are used for mass production. Many companies have their own captive TR or they assign the work to the professionally managed TRs. The workflow starts in the ToolRoom once it receives the Product Model or the Product Design / Drawing. Before accepting the model, the TR professionals check the manufacturing feasibility of the Tool for the product. Fig 6 (b) Store the Tools in Tool Room
  41. 41. 41 7. CONCLUSION The mechanical maintenance department is responsible for the running of DLW. It ensures that the all the machinery and equipment are running at their top performance level without being affected by failure and breakdown. Working with the engineers of the mechanical maintenance department I have gained such an amount of knowledge which would not have been possible in a classroomin a similar period time. Also the practical experience I have gained here in DLW, VARANSI gave me knowledge of to what extent my theoretical knowledge learnt in my college is applicable in the field. Although the theoretical knowledge forms the base of practical knowledge required onthe field , the field job also require somedifferent set of skills which I learnt about during my training. My skills in mechanical engineering has definitely been taken to a much higher level than it was when I first joined the training program of 4 weeks back and I truly consider myself highly fortunate to get this opportunity.
  42. 42. 42 8. References 1. www.indianrailways.gov.in 2. Cris-dlw.cirs.org.in 3. www.irfca.org 4. Welding Handbook 5. Machine Handbook