Que2.23. What are the advantages, disadvantages and operations of ray ray welding? Answer Advantages of Laser Beam Welding 1. Low total thermal input. 2. It can be transmitted over long distance with a minimal loss of power. 3. There’s no vaporization of essence. 4. Heat affected zone is veritably narrow. 5. Beam can be concentrated with lesser delicacy on the object as it’s light. Disadvantages of Laser Beam Welding 1. Rapid cooling rate may beget cracking in certain essence. 2. High original cost investment. 3. optic face can be damaged. 4. conservation cost is veritably high. 5. professed driver is needed for performing the welding. Applications of Laser Beam Welding 1. Cutting and welding of material. 2. Welding of nuclear factory factors. 3. For connecting leads on small electronic factors and in integrated circuitry in the electronic assiduity. 4. Transmission element for a auto. 5. For welding of high melting point essence. Que2.24. Explain the procedure of electron ray welding process. What are the difficulties encountered during EBW? Support with neat sketch. Answer Procedure of Electron Beam Welding 1. Electron beam welding can be defined as, a welding process wherein coalescence is produced by the heat attained from a concentrated ray composed primarily of high haste electrons knocking upon the joint to be welded. 2. The kinetic energy of the electrons is changed into heat on impact with work, giving violent original heating. 3. The electron ray is produced in a high vacuum terrain by an electron gun generally conforming of a tungsten cathode, a grid or forming electrode and an anode. 4. A sluice of electrons is given off from a tungsten hair hotted
to about 2200 °C. 5. The electrons are gathered, accelerated to high haste and shaped into a ray by the implicit difference between cathode and anode. 6. The ray is collimated and concentrated by passing through the field of an electromagnetic fastening coil or glamorous lens. 7. shafts are concentrated to about0.25 to 1 mm periphery and have a power viscosity of about 10 kW/ mm2, which is sufficient to melt and vaporise any essence. 8. The operation is carried out in a vacuum, which enables the ray source to be at a distance of upto about 1 m from the work. 9. Deep penetration with a veritably narrow heat affected zone is achieved by this process. 10. Aluminium can be fused upto a depth of about 40 mm, and pristine sword upto 30 mm, with a range of emulsion area of about one- tenth of the penetration. Difficulties Encountered During EBW 1. In EBW or vacuum welding system, atmospheric scattering and energy immersion of the ray are negligible. 2. also vacuum prevents the reduction of electron haste still, the size of the vacuum chamber needed naturally imposes serious limitation on the size of the workpiece that can obstruct the passage of ray and absorb some of its power. 3. also if the welding is carried out in a vacuum chamber, considerable time is lost as the work chamber must be pumped down for each new workpiece. 4. These difficulties lead to the development of some electron ray machine that permit the workpiece to remain outside the vacuum chamber while it’s being welded. Que2.25. What are the advantages, disadvantages and operations of EBW? Answer Advantages of EBW 1. Welds produced are of high quality and can be made at high pets. 2. The emulsion zone and the heat affected zone are extremely narrow. 3. Small thin corridor can be welded to heavy sections. 4. Precise control is possible. Disadvantages of EBW 1. original cost of outfit is high and movable outfit is rare. 2. Work is to be manipulated through vacuum seals. 3. Workpiece size is limited by the work chamber confines. Applications of Electron Beam Welding 1. For welding of refractory and reactive essence. 2. Low deformation factors can be welded which are used in machine, aerospace shuttle, planesetc. 3. Gear cluster for transmission system and driven shaft. 4. Intricate stopcock arrangements made from erosion- resistant blends and pressure capsules. Que2.27. Explain ultrasonic welding, with the help of neat sketch. Also give its operation, advantages and disadvantages. OR Explain with neat labelled sketch the working of ultrasonic welding. Answer Ultrasonic Welding 1. Ultrasonic welding is a type of radiant welding process thus it is considered as a advance welding fashion. 2. Through ultrasonic welding numerous essence could be combined that could not be welded by any other joining processes. 3. In ultrasonic welding, metallic tip wobbling with ultrasonic frequence is produced to weld a thin plate to a thicker one supported on an anvil, range generally used of frequence from 20000 Hz to 60000 Hz. 4. Ultrasonic welding combines pressure and high frequence vibration stir to form a solid state bond. Working Principle of Ultrasonic Welding 1. This welding is produced due to vibration generated during the welding process. 2. Workpiece that’s to be welded should be duly clamped between the welding tip and anvil in the process. 3. Both tip and anvil are faced with high speed sword. 4. In ultrasonic welding, a frequence convertor is used which converts 50 Hz line power into a veritably high power. 5. This system consists of transducer which converts electrical power into ultrasonic vibration energy and this vibration energy is transferred into joint through welding tip which is attached with transducer tip, oscillates in the aeroplane
of the joint interface. 6. frequence and the pressure wielded on the material depend on the type and size of the rail and type of welding machine. 7. During ultrasonic welding, climate combine with static setting force and produce dynamic shear stresses in the workpiece which results in plastic distortion. 8. At the joint interface, any coating or any other oxide coating are shattered and dispersed so that intimate contact and relating on the workpiece face take place. Advantages of Ultrasonic Welding 1. Stronger joint is produced. 2. Welding of aluminium to glass is possible. 3. There’s no need for sediment junking because it removes automatically due to vibration. 4. minimal face distortion results. 5. Different essence having different melting point can be joined fluently. Disadvantages of Ultrasonic Welding 1. It’s confined to aluminium. 2. This process is applicable upto3.2 mm consistence. 3. Due to fatigue lading, the life of outfit is short. 4. Material being welded tends to weld with the tip and anvil. 5. Ultrasonic welding isn’t economically competitive to other processes. Applications of Ultrasonic Welding 1. Joining of electrical and electronic factors. 2. deep sealing of unpredictable substances. 3. Welding of aluminium line and distance. 4. Fabricating of nuclear energy rudiments. 5. Strainer defenses have been welded without congesting of the holes. Que2.28. What do you understand by explosive welding? Write its advantages, disadvantages and operations in detail. AKTU 2018- 19, Marks 10 Answer Explosive Welding 1. Explosive welding is a solid state welding process wherein coalescence is produced by making one part strike over another part at a veritably high but subsonic haste. 2. This can be done by the use of explosive generally ammonium nitrate base. 3. principally explosive welding involves a high haste oblique impact between a plate propelled by an explosive charge and a stationary plate when two plates are to be strongly welded. Advantages of Explosive Welding 1. Simplicity of the process. 2. Extremely large face can be clicked. 3. Welds can be produced on heat treated essence without affecting their microstructures. 4. The foils can be clicked to heavier plates. 5. Wide range of consistence can be strongly sheathe together. 6. Good explosive bonds have strength equal to or lesser than that of the weaker of the two essence joined. 7. Lack of porosity, phase changes and structural changes conduct better mechanical parcels to the joints. Disadvantages of Explosive Welding 1. In artificial areas the use of net will be oppressively confined by the noise and ground vibration caused by explosion. 2. The regulation relating to the storehouse of snares may well prove to be the main handicap to the use of explosive welding. 3. Essence to be welded by this process must retain some rigidity and some impact resistance. 4. Essence consistence lesser than 62 mm of each amalgamation can not be joined fluently and bear high explosive loads. Applications of Explosive Welding 1. This is used in welding, joining and sheathing of essence. 2. A number of different essence combinations as aluminium to sword, tungsten to sword and aluminium to pristine sword have been joined successfully with the help of explosive welding. 3. Pipes and tubes upto1.5 m length have been sheathe with this process. 4. Heat exchangers tube wastes and pressure vessels. Que2.29. Describe with neat sketches, the working principle of explosive welding. Answer 1. The leaflet plate is to be joined with the parent plate. 2. There’s a buffer above the leaflet plate which may be of rubber, cardboard or analogous material to cover the top face of the leaflet plate from damage by eruption of the explosive charge. 3. Flyer plate should be an inclination from 1 ° to 10 ° range. 4. Thick plate is called as leaflet plate. 5. Above the buffer, there’s a subcaste of explosive which is exploded from the lower edge. 6. The parent plate rests on an anvil to limit deformation of the final product. 7. As the net is burned , the eruption surge front progresses across the face of the leaflet plate in a straight-forward and uncomplicated manner. 8. The explosive impulse provides both extremely high normal pressure and a slight, fairly shear or sliding pressure between the leaflet plate and the parent plate. 9. At the point of impact, a high immediate pressure is generated which is large compared with the shear strength of the accoutrements . 10. This creates a face free from oxides and other flicks which are brought together and stick presto. 11. The haste is in the range of 150 to 500 m/ s and pressure is in the range of 700 to 7000 N/ m2.
