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.
Examples of SMAW Welds
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 nonconsumable 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
Types of SMAW Machines
AC Welding Machine ØMost common type found in homes, farms, etc. ØGood for farm repairs, light jobs. ØLow 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
Arc Welding PPE