Welding Electrodes

Welding electrodes are used in welding various metals in the fabrication of equipment for chemical & Allied industries, construction of steel structures such as bridges, factory sheds, in the manufacture of ships, Vehicles and engineering equipment. Mild steel is welded by electrodes to a maximum among all the metals & Alloys. Therefore M.S. Welding Electrode is the most widely used core wire. Besides this, special grade electrodes are being developed for specific applications.

Welding electrodes comprise basically of steel core wire and coating ingredients or flux mild steel core wires are used in majority of unalloyed steel electrodes. Besides mild steel, nickel, Nickel-copper, Nickel irons are also used in MIG & TIG welding. Stainless steel wires are also used for welding in fertilizer, chemical & surgical instrument making industry. Coating ingredients are basically rutile, potassium silicate, sodium silicate and minerals like quartz, calcite and mica. Ferro-alloys are also used in the formulations of fluxes.

Wires of different chemical compositions and sizes are obtained from different steel manufacturers. In electrode making plant, they are chemically cleaned, cut to different lengths (30 the selling prices of welding electrodes vary according to length of the electrodes and the raw material used.

There are two methods of applying Flux coating on the core wire, (a) by dipping, (b) by extrusion.

Extrusion method is very fast and economical; produces strong uniform and concentric coatings and has largely replaced the dipping process.

(a) Dipping method. Number of core wires cut to definite length is clamped vertically in a fixture and are dipped in a bath of molten flux. When a suitable thickness of the flux gets adhered to the core wire, the fixture is raised and the flux is allowed to dry.

(b) Extrusion process. Coating ingredients as discussed earlier are mixed up in desired quantities, binder (often sodium silicate) is added and the resultant mass is brought in the form of a thick, viscous, stiff paste. This paste is shaped in the form of a cylinder which is fed into the extrusion press. Core wire and thick paste of flux simultaneously under pressure pass through a die, thus attaching the flux coating on the core wire. The coating thickness depends upon the die opening and can be varied. As a next step the flux from the gripping end of the electrode is removed by an electrically rotated wire brush; after which the electrodes are fed to ovens where they are dried and baked to remove excess moisture.

The electrodes are thereafter sorted, wrapped in polythene paper, put into packets, and bulk is boxed into wooden cases. Packets and boxes generally have information about: electrode coding, electrode size, nature of current and polarity, batch number, name of manufacturer, date of manufacture, etc.

PROJECT PROFILE FOR WELDING ELECTRODE
Plant and Machinery

The machinery required for manufacturing of welding electrodes are extrusion press, dry mixer, wire drawing machine and wire cutting machine. Some of the machinery suppliers are:
1. Multirods Limited - India
2. Excel Alloys & Equipments - India
3. Eureka Systems & Electrodes Pvt. Ltd - India

Raw Material

The raw material used in the process of manufacturing of Welding Electrodes is

Mild Steel Wire and Borax.

Manpower

The manpower required for the operation of the plant are 19 production staff and 8 administrative staff.

When welding out-of-position, the molten metal tends to spill out of the joint. To offset this tendency, an electrode with a fast freezing deposit is needed.

Welding made with out-of-position electrodes is slow, relatively expensive and require a high degree of operator skill. Therefore, whenever possible, work should be positioned for downhand welding using High-Deposition electrodes

Vertical down is recommended for fastest welding of 18 gauge to 3/16" thick steel. A description of the recommended drag technique along with sheet metal procedures are given in the section High-Speed Welding