Spot Welding: What is it All About?

Blog | March 13th, 2020

A lot of metal welding industries are now considering spot welding on their daily operations. Industries that process aluminium alloy and different types of steel are resorting to spot welding because of their intended benefits.

The Spot Welding Process

Spot welding is a welding process that joins two or more light gauge overlapping metal sheets with the application of pressure and heat to the weld area. This welding process works through contacting copper alloy electrodes to the sheet surfaces without the use of any filler material.

The process involved in spot welding starts with the application of pressure and heat to the weld area using copper alloy electrodes. These electrodes then transmit an electrical current on the material through the weld pieces. The material melts, which subsequently fuses the parts together. By this stage, the current is now turned off, the pressure is maintained, and the molten nugget solidifies to form the joint.

Materials for Spot Welding

Steels are usually subject to spot welding due to their lower thermal conductivity and higher electrical resistance. One of the most suitable types of steel for spot welding is low carbon steel since they don’t crack and fracture easily. Steels with high carbon content, on the other hand, are susceptible to poor fracture toughness or cracking when spot welded.

Slightly higher current is required when welding zinc-coated galvanised steel compared to welding uncoated steels. The copper electrodes can easily degrade the surface of zinc alloys that can lead to low weld quality. Steels that are coated with zinc need a frequent exchange of electrodes or dressing of the electrode tip surface.

Stainless steels that have austenitic and ferritic grades, nickel alloys, and titanium can also be processed through spot welding.

The thermal conductivity and electrical resistance of aluminium are close to that of copper. Their only difference lies in their melting points since aluminium has a lower melting point that makes their welding possible. However, its low resistance requires them to use high levels of current whenever they are welded.

Copper and its alloys can also be combined through spot welding through the use of an electrode made up of molybdenum and tungsten. These materials have high electrical resistance and a melting temperature far above copper’s melting point that makes them suitable for spot welding copper.

Spot Welding Applications

Industries that revolve around automotive, aerospace, battery manufacturing, metal furniture, electronics, medical, and construction are all using spot welding for processing metals. When combined with various technological advancements, spot welding can easily join metals with ease in high volume.

Knowing spot welding can help you determine if it is the right welding process for your metal. To know more about spot welding, you can always talk to us at McKean’s Sheetmetal Fabricators.

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