Difference Between AC and DC Welding – 6 Points You Should Know

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A process where a metal melting takes place and filler used to create the weld or a join is known as welding.

Arc welding is of utmost importance used by the welders; it involves a power supply used for creating an arc between the intended material and an electrode at the welding points; it takes place with an Alternating current or Direct current power supply.

If the AC power supply is the source, then it will be AC welding, or if the DC power supply is the source, it will be named DC welding. Both refer to the current polarity that is running through the machining electrode. Hopefully, this article will cover all differences between AC and DC welding with a complete info guide.

Table of Contents show

‘6’ Differences Between AC and DC Welding

TypeAC WeldingDC Welding
Power SupplySwitching back and forthConstant linear supply
PolarityChanging between positive and negativeSingle polarity: it may be positive or negative
ApplicationsThick metals, Aluminium, and magnetic materials; long seam weldsOverhead and vertical; cutting tap; stainless TIG welding
StrengthWeaker strength; Heavy spatterStrong strength; Smoother
PreferencesFast fill, down hand plate, Aluminum TIGStable/constant arc
Arc belowNoYes

Let’s overview it:

1. AC Welding

AC means alternative current; it switches the flow of electrons back and forth, so in this way, voltage reverses periodically. With a 60-hertz current, AC changes its polarity double.

There are two forms of polarity; Straight polarity means electrode negative & reverse polarity means positive electrode.

However, the deeper penetration results in reversed or positive polarity of the electrodes. Hence, for getting outstanding results from welding, choosing the right type of polarity is so essential.

Types of AC Welding

  1. Tig welding with high frequency on Aluminium
  2. Down head welding on heavy plate
  3. Fast fills welds
  4. Fixing blow arc problems

Electrodes to use in AC Welding

This step is essential in welding because choosing the right electrode is necessary for hundred percent outcomes. In AC, the arc tends to move out and try to re-establish itself. So use electrodes with specific elements coating that helps in keeping the arc ignited. 

6011 rods: Hold a high level of cellulose potassium-type coating, which is useful for all-position welding.  

7024 rods: These work well on AC for horizontal, flat welds, and general fabrication. 

Advantages

  • AC welding is best useful for welding two or more magnetic metals
  • Arc remains stable and easy to control due to not affected by magnetism
  • Excellent source for welding at high temperatures so you can weld TIG on aluminum efficiently
  • It cleans the surface by removing oxide from it when it switches to electrode positive
  • In ship buildings, when you demand deeper penetration of metals
  • Best suitable for magnetized materials melting because it doesn’t affect by magnetic interference
  • Best useful for aluminum welding on a very high frequency due to working at high temperatures

Disadvantages

  • The welding quality isn’t too smooth
  • It produces more splatter than DC welding
  • Arc handling is problematic in it

2. DC Welding

Electricity flowing in a steady constant direction where charges travel in one direction and return straight polarity is known as Direct Current.

DC welding uses Direct current for metals and other materials welding. In this, electrode negative provides faster deposition rates, and electrode positive offers deeper penetration.

Types of Welding using DC

  • Hard facing welding
  • Carbon brazing (single) 
  • Heavy weld deposits buildup
  • Mild steel electrode
  • Cast iron and sheet metal welding

Electrode to use in DC Welding

6010 electrode is the best option for DC welding because it is specially designed for direct current use. Further, this electrode consists of cellulose sodium-type coating, so it provides excellent penetration than other electrodes. So choose it if you are going to do DC welding. 

Advantages

  • DC offers more features than AC welding
  • It produces less splatter than AC
  • Best for beginners who are learning to weld and resulting welding appearance is also excellent
  • Its straight polarity welds better thinner metals, and it is effortless to start
  • Cutting taps welding is done excellently with it and best suitable for vertical welding
  • Due to the constant direction of the current, it produces a smoother weld
  • It maintains a stable arc. Hence it’s easy to handle
  • Less Expensive or cheaper machinery used in this welding

Disadvantages

  • DC demanded an internal transformer for current switching, so DC welding becomes expensive
  • It doesn’t produce high-intensity heat, so it cannot weld aluminum better

Factors involved in welding strength

  1. A number of factors involved in welding strength, regardless it is an AC or a DC welding.
  2. Right electrode and welding apparatus.
  3. Properties of the materials which are going to be weld.
  4. Proper edge preparation for better welding.
  5. Current settings (AC or DC) for welding.
  6. Traveling speed of the electrode.
  7. Appropriate polarity depending on the welding material.

Bottom Line

AC VS DC welding is useful for accomplishing different tasks. Which you have to choose is depends on the material type.

Secondly, choosing the correct electrode is also essential for better welds. Incorrect polarity and current lead to low penetration, excessive splatter, lacking arc control, and overheating issues.

Hence, complete research about conditions and materials composition before choosing the AC vs DC welder.

Moreover, DC welding holds more advantages than AC welding, and it is more useful in low voltage devices like a remote control. AC welding is preferable where high-intensity temperature required for melting metals. 

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