CONSUMABLES CORNER
Changing over to metal-cored wire in SAW
One of my vendors recently
approached me about replacing the
solid wire in my submerged arc
welding (SAW) application with a
metal-cored wire. Should I consider
making the change?
Depending on your application, you should
certainly consider making the change.
Metal-cored wires can provide substantial
benefits in SAW, including welding structural steels, pipes, boiler and pressure vessels,
ship plates, cast steels, and fine-grained
steels on carbon and certain low-alloy
steels.
Several classifications of metal-cored
wires have been developed that can be substituted anywhere a corresponding solid wire
is used (for example, EM12KS metal-cored
wire for EM12K solid wire).
With a solid wire, the welding current is
carried by the entire cross section of the
wire, and the resulting molten droplets are
large. Metal-cored wire produces finer
droplets and a less turbulent weld pool
because the current is concentrated on the
outside sheath of the tubular wire. Because
of the spray transfer pattern, metal-cored wire
can bridge gaps and help eliminate cold lap.
It is ideal when fit-up is less than optimal. In
addition, because of its broader penetration
profile, metal-cored wire can weld thin
materials with less chance of burn-through.
Perhaps the best reason to use metal-cored wire with the SAW process is the
high deposition rates. With the same flux,
welding current, and electrical stick-out,
metal-cored wire can allow you to either
reduce the number of passes or increase
your travel speed. Depending on thickness,
speed increases of 10 percent to 15 percent
are not uncommon.
MICHAEL
OSTAFFE
Finally, there is a cost difference between
using metal-cored and solid wires. It is
important to distinguish between product
price and total cost. The product price is
what you pay upfront, typically in dollars
per pound of wire. The total cost is the
overall expense of using the product, typically
in dollars per pound of deposited weld
metal. Total cost takes into account the
price of the wire and all other welding costs,
such as flux and labor.
Labor accounts for up to 85 percent of
the cost of a weld. Because of its higher
deposition rates, metal-cored wire can provide labor cost savings that more than offset the higher price of the wire. So, while
the price of metal-cored wires is typically
higher than solid wire, your total cost may
actually be lower. As a rule of thumb, you
will have the greatest chance of seeing a
total cost reduction with metal-cored SAW
wires if you are welding on thin steel at
high speeds. ■
Michael Ostaffe is vice president, product management
and development, filler metals, for ESAB Welding &
Cutting Products and is located at the Filler Metal
Manufacturing Center, 801 Wilson Ave., P.O. Box
517, Hanover, PA 17331.
Do you have a consumables
question for Michael?
Send your questions to:
Amanda Carlson, Associate Editor
Practical Welding Today
833 Featherstone Road
Rockford, IL 61107-6302
Fax: 815-484-7788
E-mail: amandac@thefabricator.com
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