What is Proper Weld Penetration?

Posted: June 15, 2014 By: Louis Beaudreau

When welding, it is always important to achieve full and proper penetration with each weld. This will ensure that the weld is clean, strong and secure. In order to understand and accomplish proper weld penetration each time you weld pieces together, think of the arc of your welder as as having a range within which you can have some control over the amount and area of heat. The longer the arc range, the higher the temperature, and if the arc gets too long, the color and sound can change from a subtle hiss to a sharp crackle with excessive spatter. If the arc is far too long, it will go out; if the arc is too short, the rod will stick causing the welding machine’s output to short circuit and overheat the rod.

If you were to look at a horizontal cross section of a proper weld, you will see that the welding bead creates a circular, eye-shape on the top of the metal piece, penetrating towards the bottom of the piece. The weld buildup should be well-contained in a round bead on the metal, not spilling, hanging over and overlapping (overlay), or thin and pointed with grooves on either side of the bead (undercutting). If you achieve a nice round weld bead, you will each proper weld penetration through the metal piece. Another key to this is to make sure that the two pieces of metal that you are welding are securely clamped together as well as tack welded in different places to avoid any shifting during the welding process. This is especially true for thin sheet metals as heat spreads very quickly in sheet metal and could cause a weld to spread apart instead of penetrate through to the base metal piece. It is always best to practice on scrap sheet metal to make sure you can achieve proper weld penetration before working on a big project.

To learn more about welding and for more automotive FAQs, be sure to visit Eastwood.com.

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