A spot welding machine is also known as a direct resistance spot welder. This equipment is used in a variety of metalworking environments to weld several thin sheet metals together. The welding process is actually quite simple; the arc is created by feeding a narrow gas or fuel into the welder, and the welder combines the gas and the metal while heating it up. Spot welding is often a very simple and inexpensive way to build strong metal pieces, many times consisting of only a few metal sheets or even a single sheet.
Spot Welding Machines come in different shapes, sizes and types. Some of these machines are self contained meaning that they don’t require any external power to operate, and are usually a compact design. In addition, many of these units are battery operated, which makes them more portable. These welding machines are most often used for metal fabrication, cutting and bending. These units have many different parts and components which need to be carefully attached and removed for proper welding, and this is where the unique benefits of a spot welding machine comes in; the compacting machine allows the welder to work in a smaller space than traditional welding methods. This means that there is no need to worry about an obstruction in the welding area, or any other safety hazard that would be present if the welding process were to occur in an open area.
There are two common types of electrode selections for welded spot welding machines. One option is to use a flux cored electrode, which the welder uses to melt the spot and apply the welding electrodes. The other option is to use a conductive welding electrode, which is similar to the flux cored electrode, but allows the welder to place the electrode in a conductive metallic surface without having to melt or apply flux to it first. Both types of electrodes are placed in the welder’s receptacle, which has a cover to prevent damage to the welded piece while it is in use. Once the welding process is complete, the cover will be removed and the welded spot will then be removed from the receptacle and trimmed to the exact thickness that was needed.
In order to weld using this type of machine, the welder must apply electrical current to the metal being welded. As the electrical current is applied, the metal becomes subject to micro-structure changes due to the electric field that is generated as a byproduct of the electrical current passing through the metal. This microscopic change in the metal changes the lattice structure and causes the formation of bonds between the various metal oxides that are part of the microstructure; as these bonds are allowed to grow, the resistance to the welding process weakens and the final weld is easier to obtain. This method allows for the welder to perform a higher level of welding since there is not the same amount of heat produced from the welding process required to create a strong bond.
The ability to create a more intense arc is one of the main differences between a portable and a stand-alone spot welding machine. Stand alone units often contain their own power supply and use a tachometer to determine the current flow; portable units must rely on a battery and their own internal tachometer to achieve the weld current necessary for the job at hand. Because of this tachometer-based weld time, they usually weld faster than portable machines. In some cases, however, such as with thinner metals where the welder must create an arc between several smaller metal pieces, the portable units can sometimes achieve a weld faster than the stand-alone units. Because the tachometer creates a reading of how long the current has been run, the welder is able to determine the appropriate arc length needed for the job.
This type of weld process is more difficult to learn, and in some cases requires a higher level of skill than other types of metal fabrication. Due to the increased difficulty in learning the proper arc speed and electrode selection for the welding process, many manufacturers offer classes to help new welders become more proficient at this skill. Most stand-alone welders that are available to consumers come with step-by-step instructional videos that teach the welder how to do the job. Online forums also provide advice and support from welders who have previously worked with the same types of machines as you will when you shop for your next portable welders.