If you have already chosen not to use Gas Metal Arc Welding (GMAW,) then you need to choose what flux core wires you're going to use.Unlike the solid wires used in GMAW, flux core wires contain a material to facilitate your welding. Whether you should choose gas-shielded or self-shielded flux core wires depends on the nature of your project and how much you want to spend.
What the flux cores do
A gas-shielded flux core speeds up the welding process. It can deposit considerably more pounds of wire per hour in a flat position than a solid wire welder. It does not work as well on thinner applications, such as auto body.
A self-shielded flux core serves to produce the gas shield that both gas-shielded and solid wires require to protect the puddle of metal. There is no need to determine the proper mix of gas for a given job and given wire. Like gas-shielded flux, it works well on thicker applications, largely because the core is capable of depositing larger amounts of wire.
Because of the slag system in a gas-shielded flux core wire, it can be welded at higher amperages than solid wire, and the weld puddle does not become too fluid. Wires of a larger diameter wires can be used. The slag system also makes the gas-shielded easier to work with in vertical uses--because the slag holds the fluid in place much better than a solid wire. The slag is also easier to remove than with a self-shielded flux core.
A self-shielded flux core does provide a good slag to hold the fluid in place, but at the end of the job, it can be more difficult to remove in order to have a weld that is clean in appearance. As in the gas-shielded, the slag system is capable of holding the liquid in place and protect it as it hardens, which allows for larger diameter wires and more vertical work than with solid wire.
A gas-shielded flux core relies on the gas that you use for welding, just as its solid wire counterpart does. In locations with a wind stronger than 5 mph, it will be necessary to block your work with a wind shield. Without something to guard against the wind, the gas will not reaching your weld, and it can cause the weld to lose integrity
A self-shielded flux core can be used in higher winds as it does not require gas to create a stable weld. The necessary materials for that are already in the flux core.
With gas-shielded flux cores, you need to remain close to a source of the gas that you use for welding.
A self-shielding flux core gives much more portability, as you are not limited by keeping a gas source nearby as you work. You don't have to be tied down to a sport or haul as much to another location.
Self-shielded flux is a little more expensive than gas-shielded wire, but you should take into consideration the cost of the gas, portability, and how long it will take to remove the slag.
- Photo Credit Image by Flickr.com, courtesy of Jason Turner
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