Through repeated heating and pressing of the welding spot on the metal sheets that are being joined, portable spot welding machines are able to fuse multiple metal sheets together permanently. The term ‘spot’ in this welding technique refers to the initial welding location where the heat and pressure exerted both on the welding equipment and the metal sheet that are to be joined. Portable spot welding is a form of direct metal arc welding (DMAW) that uses tungsten electrodes that require electrical contact with the welding workpiece in order to join the two. Spot welders, which are also popularly referred to as direct metal arc welding machines, are used mainly for fabricating metal items such as tanks, pipe, wires, bolts and many more.
DMAW is a versatile technique that is employed to weld various materials using the most current technology available. In most cases, it is used for welding thinner metals than lead and aluminum. Portable welders are generally made up of one or more vapor driven electric gun (VCD) or one or more gas driven electric gun (GIAP) in its design. Vapor driven guns are very convenient because they produce excellent quality welds with minimum heat distortion; however, they tend to be much more expensive than gas driven guns. Gas driven guns, on the other hand, are suitable for joining thicker materials.
Depending upon the job requirements and the specific welding job to be performed, the user needs to choose the appropriate welding machine. For example, if the task is aimed at joining thin sheets of metal and only minimal heat is required, a portable welder like the CO2 jet gun would be the best spot welder. On the other hand, if a user requires to join thicker sheets, it is advisable to use the GIAP or a high output CNC welding machine. The choice is entirely up to the user.
Portable spot welders come in different types to meet the various welding requirements. Some can work with a lower or higher voltage and some operate using a constant voltage system while others are only intended for work involving stainless steel welding. Based on the voltage requirement, the gun can be either direct or alternating current (DC). Depending on the current requirement, the equipment can either use permanent or disposable electrodes.
Among the different types of portable spot welding machines available, the most widely used are welding machines that work by applying pressure to apply the heat needed to weld metal sheets. This type of welding is more suitable for use with thin sheets of metal without causing too much heat distortion. This type of machine can also be used to weld corrugated tubes, sheet metal, and tubing. Unlike DC power portables, these do not suffer from voltage drops while welding and they also do not require a cooling fan.
Electric arc welding machines are also known as DC machines. They are more suitable for welding thickly constructed metal sheets and corrugated tubing. On the other hand, gas portable spot welder is suitable for welding thinner pieces of metal with the help of propane flame. The portable type of this kind of welding machine does not cause much heat distortion. The gas port is also safer than the electric one because it does not produce sparks unlike the electric one which often causes sparks when welding thicker pieces of metal.