Projection Welding Defects And Causes

If the cross section of metal in the projection is fractured the heat build up will form more rapidly in the stretched material then at the work piece interface area. Do not use excessive current.

Pdf Analysis Of Various Defects Involved In Welding Metallurgy

Metal thickness and composition is a significant matter here.

Projection welding defects and causes. Other causes include an excess of hydrogen in the alloy. When the projection is totally collapsed further growth of a weld nugget will. Issues with high electrode follow-up high current and welds too close to the edge may cause the expulsion of molten metal during welds.

One projection can overheat which could lead to expulsion. When the projections make contact at the same time but they are different sizes they can heat at different rates. When welding multiple projections if the projections are not the same size shape or missing there is a potential for inconsistent welding.

Welding defects are the irregularities that are formed due to the wrong welding process or due to inexperienced welders. Avoid rapid cooling of weld metal. In most applications one of the workpiece surfaces features multiple small formed projectionsround dimples elongated ridges or rings or the extended.

Welding defects are generated in a welding job due to the faulty or poor technique used by the inexperienced or unskilled welder or due to fundamental difficulties in the welding operation. PROJECTION SIZE OR SHAPE. Cracks and Holes High current low force expulsion and other systematic problems may cause cracks and holes in welds.

Select the electrode suitable to base metal. Lamellar tearing is a type of welding defect that occurs in rolled steel plates that have been welded together due to shrinkage forces perpendicular to the faces of the plates. Improper gas shielded may also cause this defect.

As another method it is considered to change welding order. Even some coppers and brasses cannot be welded using projection welding. 5 Causes of Weld Failures and How to Prevent Them.

The longer the arc the more chances of getting this defect. Lamellar tearing is caused mainly by sulfurous inclusions in the material. The metal mostly used on building or engineering may not be rigid enough to support the projections.

Weld metals is too rapid or improper electrodes are used these defects are liable to arise. An ideal weld or good weld should be such that adequate fusion exists between the filler metal and edge preparation together with good penetration. When the rigidity of joints is great preheating and peening is required.

Even if irregularities are very minimal but if the shape size and quality of the weld are way different than what is expected it is also called welding defects. Whatever the cause there is the potential for these failures to be catastrophic should they occur in a load. Weld failures can result from weld defects such as cracking or inclusions but there are a number of other issues in the welding operation that can also contribute to the problem.

Disadvantages of Projection Welding. This will result in the projection collapsing before fusion takes place. Projection welds developed via the resistance welding RW process use the design or shape of the part to make discreet individual-point contacts to concentrate the current during welding.

Projection welding is a resistance weld where the design or shape of the part is used to make discreet individual point contacts to concentrate the current during the welding process. In most applications multiple small projections are formed on one surface of the parts to be welded. You cannot apply this welding method on every type of materials.

High Welding current can cause this defect.

Causes And Effect Diagram Of Welding Defects Download Scientific Diagram