An MMA welder, also called a stick welder, is an electrical transformer that delivers a high level of electrical current at the output. The outlet of the welder consists of a ground cable to be connected to the part to be welded and a cable equipped with an electrode holder.
When you bring the electrode, generally referred to as the “rod”, close to the part to be welded, a short circuit and a high temperature electric arc occur, which locally melts the metal of the parts to be welded as well as the electrode itself. This is composed of a metal core that will make up the filler metal for welding and a coating that will form a protective layer against oxidation. This protective layer is called the “slag” and it must be removed when the weld has cooled. Electrodes are therefore consumables whose composition and diameter must be adapted to the work to be carried out.
The main difficulties of arc welding are:
• The difficulty of priming: if the electrode is too close to the parts to be welded when you start welding, the electric arc will not form and the electrode will stick to the parts to be welded, causing a direct short circuit.
• The difficulty in maintaining the right distance between the rod and the parts to be welded: due to the wear of the rod, the person welding must constantly adjust his or her position.
Transformer welders are called “shunts.” MMA inverter welders are an evolution of this technology, they use an electronic transformer that continuously regulates the output power. MMA inverter welders are more compact and lightweight, they allow for a better welding quality thanks to their precise power regulation and are generally equipped with a safety device that cuts off the current in case the electrode is sticking.
An MMA welder is more suitable for small jobs (repairs, etc.) than for production:
– it is easier to transport because it does not require a gas bottle
– it is less disturbed by drafts for outdoor use – it can be used to weld most metals by simply changing the rod
– it enables difficult access welding thanks to the length of the rods
– it is the most inexpensive technology