ARC WELDING MACHINE AND PROCESS
Arc Welding is a welding process where in coalescence is produced by heating with an electric arc. Mostly arc welding is done by without pressure and with or without use of filler metal depending upon the plate (object) thickness.
In arc welding machine arc is formed when an electric current passes between two electrodes separated by a short distance from each other. In arc welding machine one electrode is the welding rod or wire while other is the metal to be welded (work piece), electrode and plate. Arc connected to the supply one of the positive pole and other to negative terminal. Arc is started by moment rally touching the electrode on the plate and the withdrawing it to about 3 to 4 mm from the plate. When the electrode touches the plates, a current flows and as it is withdrawn from the plate the current continues to flow in the form of a spark across the very small gap first formed, this cause the air gap to become ionized or made conducting and as a result the current is able to flow across the gap even when it is very wide, in the form of an electrode must always be touched on to the plate before the arc can be started.
Arc is generated be electrons flowing from negative (-ve) to positive (+ve) terminal and electrical energy is changed in the arc into heat and light approximately 2/3 of the heat is generated near the positive (+ve) terminal which burns into the form of a creater. Temperature range from 2700oC-5500oC. While remaining 1/3 is generated near negative (-ve) terminal as electrode connected with positive (+ve) terminal they will burn away 50% faster than if connected to negative (-ve) terminal. Therefore medium coated electrodes and bare electrodes are used.
Types of Arc Welding Machines
1. Consumable Electrode Process
i. Shielded Metal Arc Welding (SMAW) or Arc Welding Machine
ii. SAW Welding Machine
iii. MIG Welding Machine
iv. FCAW Welding Machine
v. Electrogas Welding (ECW)
vi. Electroslag Welding (ESW)
vii. Carbon Arc Welding (CAW)
2. Non-consumable Electrode Processes
i. TIG Welding Machine
ii. Atomic Hydrogen Welding (AHW)
iii. Plasma Arc Welding (PAW)