Spot Welding Process Parameters Pdf
The spot welding process tends to harden the material, causing it to warp. Projection welding is a modification of spot welding. As such, dragon magazine 325 pdf the heat energy distribution in spot welding could be dramatically changed by the fast motion of the melted metal. There is also a control box that manages the switch and may monitor the welding electrode voltage or current. The weld time shall cause the nugget diameter to be big when welding thick sheets.
The perimeter of the spot will conduct away a lot of heat and keep the perimeter at a lower temperature. The equipment may seek to control different variables during the weld, such as current, voltage, power, or energy. Pirooz Marashi weld performance. This indicates that the correct weld current has been reached.
He metallurgical test to characterize the spot weld growth. The welding electrodes are part of the transformer's secondary circuit.
This decrease in voltage results from the reduction in resistance caused by the workpiece melting. Weld time should be as short as possible.
This reduces the material's fatigue strength, and may stretch the material as well as anneal it. Otherwise, an impressive but totally undesired shower of sparks and hot metal will issue from the weld spot. That heat and the clamping force will soften and smooth out the material at the electrode-material interface and make better contact that is, lower the contact resistance.
Weld time is the time during which welding current is applied to the metal sheets. Electrically, metallic objects have some level of resistance to the flow of electrical current.
Process parameters with their levels Sr. Optimization of Process parameter in Resistance spot welding for unequal thickness sheet using the Grey Relational Analysis. The descending order of parameters Engineering, vol. Electrode force Diameter of the electrode contact surface Squeeze time Weld time Hold time Weld current The determination of appropriate welding parameters for spot welding is a very complex issue.
He concluded behaviors of them are limited. When weld current becomes to high spatter will occur between electrodes and sheets. When the electrode force is increased the heat energy will decrease.
However, the force must not be to large as it might cause other problems. As the weld time is, more or less, related to what is required for the weld spot, it is difficult to give an exact value of the optimum weld time.
An important feature of the transformer is it reduces the current level that the switch must handle. Once melted however, the zinc would puddle around the weld zone and would provide lower resistivity as compared to bare steel onto bare steel. Consequently, more electrical energy will go into the workpiece and the junction resistance of the two workpieces. The characteristics that makes steel easier to resistance weld than aluminum is its higher electrical resistivity and its lower thermal conductivity as compared to the copper electrodes.
It only requires o C to melt the coating. Electrodes used in spot welding can vary greatly with different applications. The diameter of the electrode which make contact with the workpiece will determine the density of the electric current. The resistance presented to the welder is complicated.
Interested in career opportunities at Welding Technology Corp? One problem, though, is that the size of the contact surface will increase during welding. From Wikipedia, the free encyclopedia. The first pulse will soften the metal. The weld current should be kept as low as possible.
It is a subset of electric resistance welding. Forcing a large current through the spot will melt the metal and form the weld. This resistance will cause heat energy as electric current passes through the workpiece. Adjust the tap switch so that proper welding current can be obtained with the percent current set between seventy and ninety percent.
Heat is concentrated at the projections, which permits the welding of heavier sections or the closer spacing of welds. There is also the contact resistance between the welding electrodes and the workpiece. Occupational Safety and Health Standards. To keep the same conditions during the hole welding process, the electrode force needs to be gradually increased.
Spot welding parameters
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