Manual Metal Arc Welding (MMA) & Gas Metal Arc Welding (GMAW)

Introduction: Manual metal arc welding was first invented in Russia in 1888. It involved a bare metal rod with no flux coating to give a protective gas shield. The development of coated electrodes did not occur until the early 1900s when the Kjellberg process was invented in Sweden and the Quasi-arc method was invented in the UK. But the coated electrodes used these days were slow to be adopted because of their high cost. But because …

…between short circuiting giving hotter welding. Advantages: 1- Good manual application 2- Capable of a high degree of mechanisation 3- Applicable to most coppers and copper-based alloys 4- Good mechanical joint properties 5- No flux requirements 6- Heat affected zone can be localised 7- Low distortion when properly controlled 8- Low cost filler metals Disadvantages: 1- Fusion of parent metals may create metallurgical problems and porosity in joint. 2- High degree of manual skill required.