MMA welding (process number 111) is a type of fusion welding, specifically arc welding using a metal electrode. With manual arc welding (using a stick electrode), both AC and DC currents can be used.

        The process starts with contact ignition, and a brief short circuit must occur to establish the current between the electrode and the workpiece before lifting the electrode to start welding. It is important to ignite the arc only on the area to be welded, unlike outside the welding area. The welding current needs to be adjusted based on the type of joint and the thickness of the base material. The voltage of the welding arc is determined by the length of the arc, which the welder must control.

        The MMA welding process is popular among welders due to its versatility. It can be used on various metal types, shapes, and thicknesses, making it a favored welding process in many industries.

        Welders can choose from a range of stick electrode materials with different coating compositions, which affect the melting characteristics of the electrode, its welding properties, and the resulting weld's quality. 

        The welding current and polarity are set based on the type of electrode and metal being welded. Welders can use DC straight or reverse polarity as well as AC in conjunction with suitable welding machines. DC straight polarity is ideal for welding thinner materials, while DC reverse polarity is suitable for thicker materials. AC polarity is rarely used due to the difficulty of stabilizing the welding arc. 

        In MMA welding, the electric arc is formed between the metal electrode and the workpiece being welded. The electrode melts and combines with the metal being welded to create a bond. The shielding gas and flux from the electrode prevent atmospheric contamination of the weld. One significant drawback of using a stick electrode is that the slag produced during the welding process must be removed manually after each pass, which slows down the welding speed and adds to the cleaning process. 

        The MMA welding process is ideal for welding outdoors, in tight spaces, and particularly for situations where portability is essential. The process doesn't require additional shielding gas, making it easy to set up and efficient for on-site or field welding. While it's a versatile process that can be used on many metal types, including iron, steel, and non-ferrous metals, the quality and consistency of the weld can vary based on the operator's skill level. 

        MMA welding is a versatile welding process popular among professionals in various industries. It is a favored process for outdoor welding, onsite welding, and situations where portability is essential.

        The electrode's coating composition dictates its welding properties, and welders can choose from various materials suited for different metal types and thicknesses. The electric arc is formed between the electrode and the workpiece, creating a bond that is protected from atmospheric contamination by the shielding gas and flux. The quality and consistency of the weld greatly depend on the operator's skill level.