Spot Welding
Welders opt to use the spot welding method to quickly and easily melt and weld a spot in a material without affecting its other parts. The process therefore requires the application of concentrated energy on the spot being welded. Resistance to electric current flow produces the heat needed for welding. The pieces to be welded together are fused by pressure exerted by electrodes. Welders typically use copper alloy electrodes to weld two sheets, usually 0.5 to 3.0 mm thick, together in a spot. The resistance to the electrodes and the amplitude and duration of the current all determine the amount of generated heat. Inappropriate amounts of energy will not produce the desired welding quality.
How Spot Welding Works
Spot welding begins once the electrodes are brought to the metal’s surface and some pressure is applied to it. The next phase involves the brief application of the current derived from the electrodes. Finally, the current is removed while the electrodes stay in place to allow the material to cool.
Weld times run from 0.01 seconds to 0.63 seconds, depending on the material and its thickness, the electrode force, and the diameter of the electrodes. The process requires the use of tool holders and electrodes. Usually made of copper or other low-resistance alloy, spot welding electrodes are available in various shapes and sizes, conforming to specific welding requirements. Meanwhile, welders rely on tool holders to keep electrodes in place and hold water hoses that cool the electrodes during the welding process.
In spot welding, the two materials being fused together, commonly referred to as workpieces, must conduct electricity. Once the current is taken out of the workpiece, the coolant holes found at the center of the electrodes step in to cool it. The most common coolants are water and brine solution.
Spot Welding Benefits and Applications
Speed, control, and automation are the three key strengths of the spot welding process. It does not produce unnecessarily large amounts of heat as the current transmitted through the electrodes moves in milliseconds. This makes this method far less dangerous and more energy-efficient than other methods. It also allows maximum control of welding current, thus producing longer-lasting welds. Professional welders and auto repair specialists use portable spot welding machines. However, robots are known to perform the best spot welds, and are generally used by automakers. Today’s automotive assembly lines feature swiveling robotic arms capable of producing precise currents and performing large amounts of strong and lasting spot welds.
Spot welding finds its use in a variety of welding jobs and applications, as well as in different types of metal sheets. It is widely used in the industrial, construction, and commercial sectors. Powerful welding transformers allow spot welding aluminum alloys. The automotive industry uses spot welding machine to join metal sheets during vehicle manufacturing. Orthodontists are also top users, employing small-scale spot welding equipment to adjust or resize metal molar bands. This welding method also plays a key role in battery production, specifically nickel-cadmium and nickel metal hydride batteries. Spot welding fuses battery cells, joining thin nickel straps in the battery terminals. Spot welding, unlike soldering, keeps the batteries from getting too hot.
Spot Welding
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