Main spot welding defects

See all full list on marlinwire. The defect may differ from the desired weld bead shape, size, and intended quality. Welding defects may occur either outside or inside the weld metal. The solution to this mig welding defect is to slow down your rate of travel as when get to the end of your joint.

Another potential solution is to reduce the arc gap. Cold Lap: A cold lap occurs when when the base metal is not melted well enough.

The presence of welding defects in weld nugget has been reported in some investigations. According to these studies, shrinkage void and solidification crack were two of the main reasons for interfacial failure of spot welds under tensile-shear and fatigue tests. Voids formed by expulsion generally decreased the load bearing capacity of spot welds and interfacial failure occurred more often. The trick is for weld inspectors to recognize how each of these causes contributes to a weld problem and work together with the design engineers and shop floor welders to prevent as many defects as they can before welding begins.

But life is not so breezy for aluminum, cast iron , titanium , stainless or high-carbon steels. In addition to brittleness, other common weld defects like distortion, cracking and melt-through can compromise the durability of metals (including mild steel). Resistance spot welding is used frequently as a successful joining method for a variety of work commonly in automotive and other manufacturing processes. Spot weld nugget is generally hidden between two sheets, causing its inspection difficult and expensive.

Frequently Asked Questions.

In an effort to guarantee weld quality, weld parameter settings are often set close to a splash condition. This is done so that small changes in process variables are unlikely to give small welds, but it can lead to expulsion of molten metal from the weld nugget. Arc strike cracking occurs when the arc is struck but the spot is not welded. This forms martensite, which is brittle and may lead to higher chances of micro-cracks. Usually the arc is struck in the weld groove so this type of crack does not occur, but if the arc is struck outside of the weld groove then it must be welded over to prevent the cracking.

What is difference between seam welding and spot welding? What are the typical defects in laser welds? How can you prevent welding defects? When are weld defects rejectable? Buy Spot Welders with Warranty.

Trusted Supplier to JCB. If the lubricants are not removed prior to resistance spot welding , the electrical resistivity of the surface is altere which may lead to weld defects , including porosity and cracks. Porosity, one of the most common MIG welding defects , is the result of gas becoming trapped in the weld metal. Inadequate shielding gas coverage is among the biggest culprits, and this can be addressed in several ways.

Common Weld Defects – Causes and Cures For any weld to be acceptable, it must meet three specific criteria: 1. The weld procedure must demonstrate that the weld metal will meet all the required mechanical and metallurgical properties of the design. Metallographic analysis and tensile-shear tests were implemented for weld quality detections. Weld quality dependency on welding defects was studied.

Definition: “Process of joining two similar or dissimilar metals by heat or by pressure or by both using a filler metal to achieve a defect less joint having the physical properties similar to that of parent metal”. Use this tool to troubleshoot resistance spot welding problems such as overheating, weak welds, metal expulsion, electrode sticking and more. The spot welding process tends to harden the material, causing it to warp.

The physical effects of spot welding include internal cracking, surface cracks and a bad appearance. One of the main functions of the flux coating in welding is to produce a slag which will flow freely over the surface of the weld pool to protect it from oxidation. As the slag affects the handling characteristics of the MMA electrode, its surface tension and freezing rate can be equally important properties.