Stick Welding, also known as Shielded Metal Arc Welding (SMAW) or Covered Electrode, the most widely used of the various arc welding processes, utilizes a fixed length electrode and an electric power source to join a variety of different metals. The core of the covered electrode consists of a solid metal rod that is surrounded by a covering of mineral compounds and metal powders mixed with a binding agent to help them adhere to the surface of the electrode. The core rod conducts electric current to the arc and provides filler metal for the joint. The sizes and types of electrodes for Stick Welding define the arc voltage requirements (within the overall range of 16 to 40 volts) and the amperage requirements (within the overall range of 20 to 550 amp). The current may be either alternating or direct depending on the electrode used, but the power source must be able to control the level of current within a reasonable range to respond to the complex variables of the welding process itself.
The primary functions of the electrode covering are to provide arc stability and to shield molten metal from the atmosphere with gases created as the coating decomposes from the heat of the arc. This shielding controls the mechanical properties, chemical composition, and metallurgical structure of the weld metal, as well as the arc characteristics of the electrode. The composition of the electrode covering varies according to the type of electrode.