ESAB Knowledge center.
Cored Wire Benefits
March 25, 2014
ESAB maintains a 400,000 square ft. manufacturing plant in Hanover, PA. This is one of the most modern and complete facilities for the development and manufacture of welding electrodes in the country. This Esab Group facility was the first U.S. filler metal manufacturer to become certified to ISO 9002 Quality Assurance System.
The fabrication of a flux cored electrode begins by slitting coiled sheet steel into strips. The strips are passed through rollers that form it into a U-shaped cross-section. In the same operation, the formed strip is filled with a measured amount of core ingredients. The U-shaped strip is passed through closing rolls, forming it into a tube and tightly compressing the granular core material.
The tube is then passed through drawing dies that reduce the diameter and compress the core ingredients to prevent any movement within the tube.
The ESAB research laboratory has a large staff of technicians and engineers devoted to searching out new ways to advance welding technology. In addition to performing pure research, the lab contains pilot production facilities for producing a variety of flux cored electrodes on an experimental basis.
The Dual Shield process offers many advantages, including excellent weld metal quality, high deposition rates, and ease of operation. Labor and overhead are the most expensive factors in a welding operation, usually comprising 80 to 85 percent of the total cost. Welding with high deposition Dual Shield electrodes provides an immediate means of cost reduction without an exorbitant investment in equipment. Savings with Dual Shield range as high as 60% of the total cost of depositing one lb. (0.45 kg) of weld metal when compared to coated electrodes.
High Deposition Rates
The Dual Shield process is capable of high deposition rates because of the relatively high current density. The ratio of current (amperes) to the cross-sectional area of an electrode is known as the current density. The current density within a conductor will increase as the cross-sectional area of a conductor is reduced. Resistance to current flow through a conductor also increases as the cross-sectional area of the conductor decreases. Since the thin metal sheath provides the primary current path in a flux cored electrode, the resistance heating is concentrated in a very small area and the flux cored electrode reaches its melting point very quickly, resulting in high deposition rates.
Dual Shield electrodes’ small cross-sectional current path makes the arc stream assume a more columnar pattern, which contributes to their deep penetration. The deepest penetration occurs when straight CO2 gas shielding is used. This deep penetration results in an increase in the effective throat of a fillet joint. A fillet weld made with a coated stick electrode has shallow root penetration. When the effective throat of the fillet is increased because of deep penetration, the strength of the joint does not depend as much on the exterior size of the weld. Often times, the leg dimensions can be reduced and decreasing the fillet size by as little as 1/16" (1.6 mm) can reduce the total required weld metal by as much as 50 to 60 percent.
The included angle and/or the root opening of a joint may be decreased with Dual Shield electrodes because of their small diameter and deep penetration. This tighter joint design significantly reduces the volume of weld metal needed to fill the joint. The deep penetration of the flux cored electrode also has advantages compared to solid wires. Penetration is substantially reduced with solid wires in out-of-position work due to the low current used with short circuit transfer. Reduced penetration means extra care must be taken to prevent lack of sidewall fusion. In general, flux cored electrodes can operate at higher welding currents in out-of-position work, making sidewall fusion much better with flux cored electrodes. This increased weld integrity minimizes expensive rework.
Rapid Operator Training
Welding with Dual Shield flux cored electrodes requires a minimum of training. It is much easier to train an inexperienced welder to weld in all positions with flux cored electrodes than with other welding processes, because the fast freezing slag holds the weld puddle in place, permitting greater control. Subsequently, time spent in training welders is greatly reduced and the chance that they will produce high quality weldments in a short time is increased.
Better Bead Appearance
Welds produced with flux cored electrodes are smooth with almost no ripple. The metal transfer of Dual Shield electrodes produces very little spatter which significantly reduces cleanup time.
ESAB produces the greatest variety of all-position flux cored electrodes on the market today. With all-position electrodes, the set up time and expense of fixturing is eliminated.
Even though some flux cored electrodes may cost more to buy than coated electrodes or solid wires, the real costs of a welding operation are in the labor and overhead expenses, which account for 80% to 85% of the total. Dual Shield wires, with their high efficiencies and high deposition rates, reduce labor and overhead costs, and thus, in many cases are actually less expensive to use.