Overlap occurs during a welding project when the face of the welding material left behind is larger than the opening in the metal surface. A common formal definition for overlap is welding material that protrudes beyond a weld toe or root. Overlap is also sometimes used informally as a way of referring to metal that is not completely fused.
This problem usually happens when the metal that is used for welding material rolls out and does not form a flat contact, leading to excess or "overlap" material that goes beyond the intended point. An overlap often ends up looking like a circle or spot around the area that extends into unnecessary places. Materials with overlap or lack of fusion may not pass an inspection because of the potential for the finished structure to fail under stress.
Decrease the current level
Proper levels of direct or alternating current should be set based on the specifics of each job. If your electrode looks too bright or glows, that usually means too much current is going to reach the welding point. Amperage should be set at one amp for about every one thousandth of an inch of electrode diameter. So a quarter inch of diameter would need 250 amps.
Use a smaller electrode
Larger rods and electrodes can potentially apply too much welding material to the surface. Smaller electrodes will have less of a gap and apply less welding melding at each point, which means there is not as much of a chance that excess material will cause an overlap.
Check your technique
Inexperience or a technique that does not correspond correctly to the task at hand will cause overlap. Keep in mind that welding techniques can vary greatly depending on the type of metal used, or if the welder is using MIG Welding, TIG Welding, Stick Welding, etc. All of these require different forms of preparation and cleaning, or specific materials such as shielding gas, along with techniques must be used properly to get a good quality weld without overlap.
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For more information about proper welding techniques from industry professionals, you can contact Blackstone Advanced Technologies.
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