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Manual metal arc (MMA) welding, also known as shielded metal arc welding (SMAW), stick, and electric arc welding is a constant current drooping arc process.

Tungsten inert gas welding is a constant current drooping arc process. It is also known as TIG, gas tungsten arc welding - GTAW, wolfram inert gas - WIG, and under the trade names of argon arc and heli arc.

TAFE NSW - Western Institute offers welding program like Basic Welding Skills, Gas Metal Arc Welding (GMAW), Gas Tungsten Arc Welding (GTAW), Manual Metal Arc Welding (MMAW), Welding to AS1796 Certification 1-9.

this is often referred to as the 'self-adjusting arc'. Metal Inert Gas (MIG) welding is a 'flat' arc process (constant) voltage. Also known as Metal Active Gas (MAG); CO2; Metal-arc Gas Shielded, flux core and GMAW (US).

The two main types of GMAW transfer are: Spray or globular transfer. Short-circuiting or dip transfer. Spray Transfer/Globular Transfer. This type of metal transfer generally occurs at high current and high arc voltage ranges, e.g., 250 - 600 Amps at 28 - 40 volts. As the current is increased the rate at which the droplets are transferred across the arc increases and they become smaller in volume. The droplets can be seen in a high-speed cine film but cannot be seen with the naked eye. It appears as if there is a spray of metal.

Welding Variables: Amperage : controls fusion and penetration. Voltage : controls arc length. Travel speed :controls depth of penetration. Gas flow rate :protects weld from atmosphere. Electrode extension :affects penetration.

Porosity cause by : Gas flow too low or too high. Leaking gas lines. Draughty conditions. Electrode stick out from nozzle too long. Contaminated/dirty weld prep. Contaminated/dirty wire. Incorrect gas shield. Arc length too long

It is most important to properly prepare the surface to be welded because a satisfactory weld can not be made over thick paint, rust or marine growth. The initiation of an arc may be impossible or, at best, very difficult when the surface has not been made ready for welding.

If you live at Australia and interest on welding industry, you can join TAFE NSW - Sydney Institute Welding courses to increase your welding skill and knowledge. TAFE NSW - Sydney Institute offers welding program like Flux Core Arc Welding (FCAW),

Too short an arc length will cause irregular piling of the weld metal. The ripples will be irregular in height and width.

Positional welding (other than flat) often relies on arc force and surface tension effect; therefore the welding position may affect the mechanical properties of the weld and the likelihood of defects.

The main purpose of Industrial Welding Training is helps plant maintenance workers develop a working knowledge of and learn the theory behind gas and arc welding techniques and equipment, and the cutting of steel, pipe, iron and nonferrous metals.