An arc welding power supply equipment should have the following characteristics: • must isolate the welding circuit from the mains supply. • provide the required voltages and desired welding currents for the operation. • provide the output volt-ampere characteristics which matches the arc system. • incorporate a low-voltage supply for the operation of auxiliary units. […]

• Here the situation is different, the voltage setting of the power-source and not the welder controls the arc length. • In GMA/GTA Welding the feed wire diameter is usually very small and the burn-off rates are far higher than in SMA or TIG Welding, and they vary much more with current. A small variation […]

3.2.1 Arc Welding Power Sources The various welding processes described in Chapter 2 require special power sources (having low voltage and high current for arc welding) to produce energy sufficient to make a good weld. Power sources could be a. c. (transformers), d. c. (generator/rectifiers) with constant current or constant voltage characteristics having current rating […]

3.1 INTRODUCTION After a brief review of welding processes let us go into the science of welding. This will help us in the understanding of the further discussions regarding the welding applications and tech­nologies that will follow. Most welding processes require the application of heat or pressure or both to produce a suitable bond between […]

Plasma is the fourth state of matter (other three being: solid, liquid and gas). It is hot ionized arc vapour. In arc welding this arc plasma is blown away by moving gas streams, but in a plasma torch it is contained and used effectively giving rise to the following processes: • Plasma arc welding • […]

Laser is the abbreviation of light amplification by stimulated emission of radiation. It is very strong coherent monochromatic beam of light, highly concentrated with a very small beam divergence. The beam exiting from the laser source may be 1-10 mm in diameter, when focussed on a spot has energy density of more than 10 KW/mm2. […]

2.5.1 Electron Beam welding • Electron beam welding uses the kinetic energy of a dense focussed beam of high velocity electrons as a heat source for fusion. In the equipment for this process, electrons are emitted by a cathode, accelerated by a ring-shaped anode, focussed by means of an electromagnetic field and finally impinge on […]

Explosive welding is a welding process that uses a controlled application of enormous pressure generated by the detonation of an explosive. This is utilized to accelerate one of the compo­nents called the flyer to a high velocity before it collides with the stationary component. At the moment of impact the kinetic energy of the flyer […]

• Ultrasonic process of welding is shown in Fig. 2.18. The core of magnetostrictive ultrasonic vibrations generator (15-60 kHz) is connected to the work through a horn having a suitable shaped welding tip to which pressure is applied. The combination of ultrasonic vibrations with moderate pressure causes the formation of a spot weld or seam […]

This group of welding processes uses pressure and heat (below the melting temperature) to produce coalescence between the pieces to be joined without the use of filler metal. The proc­esses under this category include: Diffusion Bonding, Cold Welding, Explosive Welding, Fric­tion Welding, High Frequency Pressure Welding, Forge Welding, Hammer Welding, Ultra­sonic Welding, etc. The important […]