Auto body spot welder online shopping UK
Spot welding of very dissimilar metals, such as aluminum and steel, is generally not possible because of different melting characteristics and conductivities. Some types of coated low-carbon steels require special techniques. Steels plated with chrome and nickel for electrical conductivity can usually be resistance welded as readily as uncoated material. Aluminum, tin, zinc and terne-coated steels are also spot weldable with special precautions and welding equipment. Some coatings can emit poisonous fumes that must be safely handled when spot welded, thereby increasing cost. Spot welding of coated substrates creates burn marks in the coating which can be unsightly and may corrode in severe environments. Designers should carefully consider the product’s appearance and service requirements before specifying spot welding of pre-plated materials.
Plug welding is an alternative to spot welding used by vehicle manufacturers where there is insufficient access for a spot welder. For DIY car restoration it’s generally used instead of spot welding on panels flanges that would have originally been spot welded. Plug welds when done properly tend to be stronger than the original spot welds. Rally car builders often use the technique, and it is acceptable in a UK MOT test as an alternative to spot welds where repairing older cars (it would not be suitable for modern high tensile steels).
Although aluminium has a thermal conductivity and electrical resistance close to that of copper, the melting point for aluminium is lower, which means welding is possible. However, due to its low resistance, very high levels of current need to be used when welding aluminium (in the order of two to three times higher than for steel of equivalent thickness). In addition, aluminium degrades the surface of copper electrodes within a very small number of welds, meaning that stable high quality welding is very hard to achieve. For this reason, only specialist applications of aluminium spot welding are currently found in industry. Various new technology developments are emerging to help enable stable high quality spot welding in aluminium. See more info on Tecna Spot Welder Parts.
Portable spot welders are compact, lightweight and handy for difficult-to-access joints. As such, they are most commonly used in coachbuilding. They have an average welding capacity of 2 + 2mm and are relatively inefficient due to the fact that the electrodes aren’t cooled between cycles. Automatic adjustment makes it easier to adjust the spot parameters according to the thickness of sheet and welding head used.
