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What are the differences between AC and DC welding plant?

Difference between AC and DC Welding Machines
Difference between AC and DC Welding Machines

Difference between AC and DC Welding Machines

Welding is a process used to join metals together by melting the parts and using a filler to form a joint. Welds can be accomplished using different energy sources from a gas flame or electric arc to a laser or ultrasound. Welding cannot be done with all types of metals. For example, stainless steel is prone to cracking and distortions when it is overheated. Alloys are often a problem because it is difficult to know the exact chemical composition of the metal.

For a welder to make the best welds he must understand what alternating current (AC) and direct current (DC) signify on the welder as well as on electrodes.

Electricity flows in two ways: either in an alternating current (AC) or in a direct current (DC). Electricity or “current” is nothing but the movement of electrons through a conductor, like a wire. The difference between AC and DC lies in the direction in which the electrons flow. In DC, the electrons flow steadily in a single direction, or “forward.” In AC, electrons keep switching directions, sometimes going “forward” and then going “backward.”

Alternating current is the best way to transmit electricity over large distances.

AC and DC are terms that refer to the polarity of the electrical current that is created by the welder and runs through the electrode.

What Is Polarity?

Every electrical circuit has a negative and positive pole. Direct current flows in a single direction resulting in a constant polarity. Alternating current or AC current flows in one direction half of the time and in the opposite direction the other half. AC current changes its polarity 120 times per second with a 60 hertz current.

Other differences between Ac Current and Dc Current.

  • In Ac, it is safe to transfer over longer city distances and can provide more power while in Dc,Voltage of DC cannot travel very far until it begins to lose energy -Amount of energy that can be carried.
  • Steady magnetism along the wire while in Ac, it rotates magnet along the wire.Cause of the direction of flow of electrons
  • The frequency of alternating current is 50Hz or 60Hz depending upon the country while that of Dc the frequency of direct current is zero.Frequency
  • Ac reverses its direction while flowing in a circuit. Dc flows in one direction in the circuit.Direction

Its ideal for the following types of welds;

1. Downhand heavy plates

2. Fast Fill

3. Aluminium TIG welding with Hi frequency

In DC reverse polarity, the electrode is positive and the current flows from the workpiece to the electrode. It is ideal for:

  • Overhead welding
  • Vertical welding
  • Cast iron welding
  • Heavy aluminium
  • Rivet welding
  • Sheet metal
  • Low hydrogen welding
  • Arc bronze rod

Safety procedures for using these Welding machines

There are requirements for personal safety equipment and fire-prevention measures that welders must observe/ abide by.

Welding fumes can cause breathing problems in welders. Some problems are short term and others may be long term illnesses like asthma. Welding fumes are also internationally classified as possible carcinogens.

Personal protective equipment for welders includes

  • Fire-resistant clothing,
  • safety glasses,
  • shoes,
  • gloves,
  • hood and welding helmet and leathers. Synthetic clothing should never be worn because it melts when exposed to extremely high heat. Wool is a better choice because it is durable and resistant to fire.

AC And DC welding are both needed to accomplish certain tasks. DC welding generally has more advantages over AC welding but the most important thing for a welder to understand is how polarity works so that the welder can choose the proper electrode with the right polarity for the job.

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