ELECTRIC WELDING

ELECTRIC WELDING 

Electric welding is the joining of metal using an electrical arc and a filler metal stick electrode or wire.

Welding is done by creating an arc between the base metal (the metal being welded) and the filler metal.

DC Welding

Direct current is an electric current that has a constant polarity flow in a single direction, that current can be positive or negative. With DC welding, since the magnetic field and current of the arc are constant, stable arcs are produced.

Advantages

• smoother welding output than  AC
•  more stable & smooth arc
• Less spatter
• DC negative offers faster deposition rates when welding thin sheet metals
• DC positive provides greater penetration into the weld metal

Disadvantages

• DC welding is unable to fix arc blow problems
• Equipment is more expensive as DC currents require an internal transformer to switch the current

Applications

DC welding is ideal for joining thinner metals as well as being used in most stick welding applications, including TIG welding of - steels. This form of welding is also good for overhead and vertical applications.

AC Welding

An alternating current is an electric current that reverses its direction many times per second. A 60-hertz current will change its polarity 120 times per second. With AC welding, because the magnetic field and current rapidly reverse -direction, there is no net deflection of the arc.

Advantages

• The alternating current between positive polarity and negative polarity allows for a steadier arc for welding magnetic parts
• Fixes problems with arc blow
• Enables effective aluminum welding
• AC welding machines are cheaper than DC equipment

Disadvantages

• More spatter
• Weld quality is not as smooth as with DC welding
• Less reliable and therefore more difficult to handle than DC welding

Applications

When switched to AC positive, it also helps to remove oxide from the metal surface, hence it is suitable for welding  aluminum