Arc Welding By Ryan Saucier
History of Arc Welding • Arc welding dates back to the late 1800’s • First developed following the invention of AC electricity • Pioneered when a man was welding with a bare metal rod on iron, the sparks from the welding caught a stack of newspapers on fire near him and while welding, he noticed that his welds started looking a lot better. The reason for this was the smoke took the oxygen out of his welding environment and decreased porosity.
What is Arc Welding? • The fusing of two or more pieces of metal together by using the heat produced from an electric arc welding machine.
Basics of Arc Welding • The arc is struck between the electrode and the metal. It then heats the metal to a melting point. The electrode is then removed, breaking the arc between the electrode and the metal. This allows the molten metal to “freeze” or solidify.
How an arc is formed? • The arc is like a flame of intense heat that is generated as the electrical current passes through a highly resistant air gap.
Welding Processes • SMAW (Shielded Metal Arc Welding) • GMAW (Gas Metal Arc Welding) • GTAW (Gas Tungsten Arc Welding) • Oxygen/ Fuel Welding
SMAW • Also referred to as “Stick Welding” • Used for everything from pipeline welding, farm repair and complex fabrication. • Uses a “stick” shaped electrode. • Can weld: steel, cast iron, stainless steel, etc. • Can also hardface with correct electrode.
GMAW • Also referred to as “MIG” welding • Uses a shield gas and a continuous wire electrode • Used for all types of fabrication • Great for thin metals up to ¼” • Excellent speed of deposition • Used for metals such as: steel, aluminum and stainless steel.
MIG Welding Benefits • All position capability • Higher deposition rates than SMAW • Less operator skill required • Long welds can be made without starts and stops • Minimal post weld cleaning is required
GTAW • Also referred to as “TIG” Welding • Uses a shield gas, a non-consumable tungsten electrode and a hand fed filler rod • Excellent for welding thin metals, pipeline welding and exotic metals • Highly skilled labor needed for this process
GTAW Welding Benefits • Superior quality welds • Welds can be made with or without filler metal • Precise control of welding variables (heat) • Free of spatter • Low distortion
Oxygen/ Fuel Welding • Utilizes oxygen and a fuel gas to heat metal until it is in a molten state and fuse multiple pieces of metal together. Can be used with or without a filler rod. • Great for brazing dissimilar metals together. • Older technology that can be replaced by GTAW
AC Welding Machine • Most common type found in homes, farms, etc. • Good for farm repairs, light jobs. • Low cost
DC Welding Machines • Often generator type machines • Diesel or gasoline engine driven • Portable • Expensive
AC/DC Welders • Can weld in AC or DC polarity • Less expensive than DC machine • Quieter than DC machine