B-13

OPERATION

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THE CORRECT ARC LENGTH

The arc length is the distance from the tip of the elec- trode core wire to the base metal.

Once you’ve established the arc, maintaining the cor- rect arc length is critical. It should be short, 1/16 to 1/8 inch (3.2 mm) long. As the electrode burns off, you must continue to feed it into the work to keep the arc length correct.

The easiest way to tell if the arc length is correct is to listen to it. A nice, short arc has a distinctive “crack- ling” sound, like eggs frying in a pan. A long, incor- rect, arc has a hollow, blowing or hissing sound.

THE CORRECT WELDING SPEED

To know whether your welding speed is correct, you must watch the puddle of molten metal behind the arc. DO NOT WATCH THE ARC ITSELF. The appearance of the puddle and the ridge where it solidifies tells the tale. The ridge should be approximately 3/8 inch (9.5 mm) behind the electrode. See Figure B.6.

FIGURE B.6 – MOLTEN METAL PUDDLE

AND CORRECT WELD SPEED

3 1

2

4

1.ELECTRODE

2.ARC

3.RIDGE OF MOLTEN METAL

4.WELD PUDDLE

Most beginners tend to weld too fast, which gives a thin, uneven, “wormy” looking bead. They are not watching the molten metal puddle.

NOTE: When welding on thin plate, you will find that you have to increase welding speed. On heavy plate, you will have to go more slowly to ensure fusion and penetration.

The key to developing welding skill is PRACTICE. No one can learn to weld just by reading about it. If you are an inexperienced welder, the information here will help you understand some basic welding principles you should know before you use your POWER-ARC 4000 for stick welding. For more detailed information, order a copy of the book New Lessons in Arc Welding, available from the Book Division of Lincoln Electric. See the form located at the back of this manual for ordering information!

POWER-ARC 4000

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Lincoln Electric SVM103-A service manual Correct ARC Length, Correct Welding Speed