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Arc welding Afrikaans | Xhosa

Click to enlarge!		 Arc welding is the process whereby metals are welded with the aid of an electric arc flame between the metal which must be welded, or mother metal, and a suitable flux, which is called the welding rod or electrode. The heat of the arc flame melts the mother metal and the electrode. After cooling down, this mixture forms a solidly joined mass.

Click to enlarge!		 Before welding can commence, a suitable power source is needed. There are two types of electric welding machines available: those using direct current and those using alternating current.

Click to enlarge!		 Welding machines using alternating current are usually of the transformer type, whereas direct current machines are of the generator type.

In order for welding to be made possible, the following requirements have to be met:

  • The machine must be attached to a suitable power source.
  • The welding cable must be attached to the contact point marked "electrode".

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  • The earth cable must be attached to the contact point marked "work".

REMEMBER: Where the contact points are not marked, any connection may be used for "work" or "electrode".

Click to enlarge!		 Let us take a look at the welding technique. To do a proper welding job one must pay attention to the following:
  • the right electrode
  • an electrode of the right thickness
  • the right welding current
  • an arc flame of the right length
  • the right angle between the electrode and the work

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  • the right speed - never draw the electrode over the work or lift up the electrode
  • the work to be welded has to be properly prepared.

Click to enlarge!		 Next we look at the welding current. When the current is too low, it is difficult to obtain the correct arc flame and to keep it right, because the electrodes stick to the work, penetration is poor, and the result is a rounded welding layer. When the current is too high it causes over-heating of the electrode, the burning away or the burning through of the mother metal, and excessive spattering of drops of molten metal.

A normal current for a given job is the maximum that can be used without causing the mother metal to burn through, or the electrode to become overheated, or resulting in a coarse, spattered surface.

The generally recommended amperage for a 3.25 mm (no. 10) electrode is 80 - 135 ampere.

Click to enlarge!		 The length of the arc flame is obtained by scraping the electrode gently over the work. The correct length of the arc flame is the shortest length which will result in a good surface to the welded joint. An arc flame which is too long reduces penetration, causes spattering and results in a coarse joint surface. An arc flame which is too short causes the electrode to stick, and results in coarse deposits.

For downward welding the arc flame length should not be greater than the diameter of the welding rod. For overhead welding a short arc flame is required so that as little metal as possible will get lost.

Click to enlarge!		 An electrode angle of 40°-50° is recommended to ensure a smooth, even transfer of metal.

Click to enlarge!		 Finally, it is important that the work / metal be prepared thoroughly.

WD Simpson
ELSENBURG / Training