Resistance welding would be like seam welding or spot welding, that’s where a pair of electrodes apply a high current to 2 pieces of metal to melt them together. heat to form the weld is generated by the electrical resistance of material vs. the time and the force used to hold the materials together during welding. Some factors influencing heat or welding temperatures are the proportions of the workpieces, the metal coating or the lack of coating, the electrode materials, electrode geometry, electrode pressing force, electrical current and length of welding time. Small pools of molten metal are formed at the point of most electrical resistance (the connecting or “faying” surfaces) as an electrical current (100–100,000 A) is passed through the metal. In general, resistance welding methods are efficient and cause little pollution, but their applications are limited to relatively thin materials and the equipment cost can be high.
Arc welding or shielded metal arc welding, is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable electrode, which adds material to the weld giving you a weld “bead”. The welding region is usually protected by some type of shielding gas and slag which comes from the flux coating of the electrode. Different electrodes are different compositions for different types of metal, give different weld strength and have different flux coatings dependant on the type of material. Arc welding can be done outdoors and in tricky places because you don’t need an independent supply of shielding gas or wire feed, used a lot in construction because of it’s portability. Also it’s not quite as dependant on the metal being perfectly clean like mig is. Different types of welder, bus boxes are the older kind, inverter amplifiers are the more modern kind and are easier to use. The electrode is struck like a match to initiate the arc, correct arc length is important to ensure correct distribution of weld material onto the parent metal. It can be used in horizontal, vertical and overhead positions depending on the electrode used.
Arc Spot Weld