March 27, 2003
Metal-cored wire is a tubular electrode that consists of a metal sheath and a core of various powdered materials, primarily iron. The core of metal-cored wire contributes almost entirely to the deposited weld metal.
Following are six important questions to ask before you decide whether metal-cored wire is right for you.
Good candidates include:
For the right applications, switching to metal-cored wire can save $100 to $200 for every 100 pounds of weld metal deposited. Typical benefits include:
Solid wire's entire cross section carries the welding current, and the molten droplets are large. Metal-cored wire's current is concentrated on the outside sheet; the metal powders inside are less conductive because of their granular nature. Focusing current on the wire's outer diameter creates a broader, bowl-shaped arc cone. It also can create finer molten droplets and a less turbulent weld pool.
Metal-cored wire's spray transfer pattern can bridge gaps and help eliminate cold lap. Even if an operator doesn't point the arc directly at the joint, or if parts in an automated application have less than optimal fit-up, metal-cored wire might be able to compensate. Its broader, more tolerant arc still could catch the toe of the joint and make an acceptable weld.
Metal-cored wire can weld thin materials without burn-through because it lacks a "deep finger" of penetration. Also, spray transfer requires less amperage with metal-cored wire. On thinner metals (1/8 in. or less), metal-cored wire may let you switch from short-circuit to spray transfer to improve travel speeds, bead appearance, and bead quality.
Yes, but you also should look beyond the cost of consumables. Filler metals make up 10 percent of a weld's cost and gas 3 percent. Labor accounts for 85 percent of welding costs. Any significant productivity increase from using metal-cored wire can outweigh an increase in consumables cost.
Steve Barhorst is tubular wire marketing manager for ITW Hobart Brothers Co., 400 Trade Square East, Troy, OH 45373, 800-346-2529, fax 937-332-5808, www.hobartbrothers.com. ITW Hobart Brothers Co. is a manufacturer of welding filler metals.
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