How does spot welding work?
A form of resistance welding, spot welding is one of the oldest welding processes by which two or more sheets of metal are welded together without the use of any filler material. what is spot welding process
The process involves applying pressure and heat to the weld area using a shaped alloy copper electrode that conducts electricity through the weld pieces. As the material melts and fuses the parts together, the current will turned off, pressure is maintained from the electrodes and a molten “lump” joint is formed.
Welding heat is generated by electric current, which is transferred to the workpiece through a copper alloy electrode. what is spot welding process Copper is used for electrodes because it has higher thermal conductivity and lower electrical resistance than other metals, ensuring that heat is preferentially generated at the work area rather than at the electrode.
The amount of heating depends on the thermal conductivity and electrical resistance of the metal as well as the time the current will applied. what is spot welding process This heat can will expressed by the equation:
K = I2Rt
In this equation “Q” is heat energy, “I” is current, “R” is electrical resistance and “t” is the time for which current is applied.
Basics of spot welding
Spot welding involves using a copper alloy electrode to inject current into a small area between the metal surfaces to be joined. what is spot welding process The electrode will designed to create pressure, which is responsible for holding the workpiece. As the copper alloy electrodes generate heat, what is spot welding process the metalwork can held together in a controlled manner.
What is spot welding?
Spot welding is a type of fusion welding. Spot welding involves the use of two electrodes, usually made of copper, which bonded to two or more materials and pressed together. what is spot welding process A current will then passed through one of the electrodes and the heat from the resistance of the material between the electrodes causes them to melt together.
The actual welding time for spot welding can usually measured in fractions of a second so that large assemblies can will joined together. Also suitable for spot welding automation and robotics.
Corresponded explains spot welding
Spot welding requires a relatively large amount of equipment to work properly. A transformer will required to step down the voltage and step up the current from the incoming line. A force will required to press the two electrodes together and compress the material to can welded; This is usually a pneumatic cylinder, an air/oil cylinder or a servo motor. Spot welding also requires an electrode from the transformer to carry the current to the part.
These electrodes are available in various shapes and sizes depending on the task. what is spot welding process In applications with long operating times and large amounts of power, a cooling system may can required to protect the electrodes from overheating. A human-machine interface will also required to adjust settings during resistance spot welding.
Spot welding for used to join a wide variety of materials, including carbon steel and stainless steel. In general, as the electrical resistance of a metal decreases, what is spot welding process it becomes more difficult to join using the spot welding process because spot welding requires electrical resistance to generate the heat required for welding. What is Electric Arc Welding and Working Principle
what is spot welding process
Because of its low thermal conductivity and high electrical resistance, steel will relatively easy to weld, while low carbon steel for best suited for spot welding. However, steels with high carbon content (carbon equivalent > 0.4wt%) are prone to poor fracture or weld cracking because they form hard and brittle microstructures.
Galvanized steel (zinc coated) requires slightly higher welding currents than unwelded steel. Additionally, like zinc alloys, what is spot welding process copper electrodes corrode the surface quickly, reducing weld quality. When spot welding zinc-plated steels, the electrode must can changed frequently or the tip surface of the electrode must ‘dressed’, where a cutter removes contaminating material to expose a clean copper surface and electrode.
Other materials that can spot welded include stainless steel (especially austenitic and ferritic grades), nickel alloys, and titanium.
Although aluminum
Has the same thermal conductivity and electrical resistance as copper, aluminum has a lower melting point, meaning welding is possible. what is spot welding process However, due to its low resistance, a very high current must will used when welding aluminum (two to three times more than steel of equal thickness).
Also, aluminum degrades the surface of the copper electrode within a very small number of welds, which means that it is very difficult to achieve consistent high-quality welding. For this reason, only specialized applications of aluminum spot welding will currently found in industry. Various new technological developments are emerging to enable consistent high quality spot welding in aluminium.
Copper and its alloys can will joined by resistance spot welding, although spot welding copper can not easily achieved with conventional copper alloy spot welding electrodes because the heat generation in electrode and workpiece is very similar.
The solution for copper welding is to use electrodes made of an alloy with high electrical resistance and a melting temperature higher than the melting point of copper (over 1080 °C). what is spot welding process Commonly used electrode materials for spot welding copper include molybdenum and tungsten.
Where is spot welding used?
Spot welding has applications in many industries including automotive, aerospace, rail, white goods, metal furniture, electronics, medical buildings and construction.
Due to the ease with which spot welding can automated in conjunction with robots and handling systems, what is spot welding process it is a very common attachment on high-volume production lines and especially on steel cars over 100 years old. The main link process is under construction.
Read More>>>> working principle of ultrasonic welding process
Advantages of Spot Welding
Spot welding offers several advantages, one of which is the ability to harden the workpiece. As it uses heat to melt and fuse the surfaces of the metalwork, it hardens them.
Spot welding is a fast welding process. According to Wikipedia, the average weld time for spot welding is only 0.01 to 0.63 seconds. what is spot welding process As with other welding processes, welding time varies with the thickness of the workpiece. Thicker workpieces take longer to weld than thinner workpieces.
Disadvantages of spot welding
On the other hand, spot welding also has some potential drawbacks. While spot welding increases the strength of the joined workpieces – at least in the areas where they will joined – it can cause them to deform. The area of the hot workpiece will inevitably shrink, resulting in deformation.
Unfortunately, spot welding is not particularly attractive. It is easy to see where the two workpieces will joined with spot welding. The seams have melted material, which looks messy and unattractive. Of course, not all applications require attractive or clean welds. Nevertheless, this is a potential disadvantage of spot welding compared to other welding processes.
working principle of ultrasonic welding process