Which Flux Core Wire To Choose – 0.030 vs 0.035
It is actually hard to tell which one you should pick. With many manufacturers, the quality of the wire varies a lot, so if you are a fan of a certain brand, I would do some testing to find out which works best for you. Many self-learned welders have their own ways to set up the machines, so some thicker wire gives better results than thinner fillers. The choice between 0.030 and 0.035 flux core wire depends on the thickness of the metal you are welding.
If you are welding thinner metal, such as sheet metal or thin tubing, 0.030 flux core wire is a good choice. It produces a smaller weld bead and is easier to control, making it ideal for welding in tight spaces or on thin metal.
It also depends a lot on the machine you are using. If you have a 220v machine and you do not have to weld very thin metal then I would definitely advise you to pick up .035 size wire. If you have a small, flux-only machine, then it might be too much for your welder to handle. If you are welding thicker metal, such as a heavy plate or structural steel, 0.035 flux core wire is a better choice. It produces a larger weld bead and can penetrate deeper into the metal, resulting in a stronger weld.
There is also a joint factor to consider. If you are welding tight joints with no caps, then a smaller diameter wire is preferred. Using thick wire with tight fittings will create higher beads, which in turn will also weaken the joint.
To make it more clear, if you have a 125 amp welder or less, I would not even consider .035 wire, but with a 140 amp welder I would try, it should have enough power to run 035 flux. With machines that pack a little more punch than 140, 035 is the minimum I would go with unless you are working with very thin metals.
Tips for using flux core welding (FCAW) method
When switching wires, also switch your contact tip to an appropriate size. For this method, since it produces a ton of spatter, I would recommend using a tip one size larger than you would normally use. For example, with a .030 wire use a .035 contact tip. It does not make welding much more complicated, but it will save you from a lot of headaches.
With flux core welding, it is important that you pull the welding gun away from the puddle, not push it towards the weld to avoid contaminating the bead with flux. As a result of pushing you will get a porosity in your bead, thus the weld will be weaker.
When installing the wire, make sure that you do not tension the drive rolls too much. Since the flux core is softer than regular wire, you have to make sure you do not crush it flat under too much pressure. Also, you must have a knurled drive roll.
Since the flux core welding is way messier have some spare nozzles at hand. Also, I would recommend you pick up some nozzle gel. I have a full article about the use of nozzle gel here. Make sure you check that out if you have never used it before.
And last but not least, be sure you are working in a well-ventilated area, or even outdoors because FCAW produces a lot more toxic gases than regular MIG welding. It will, more than likely, really damage your health in the long run. The least you can do is wear a respirator under your welding mask.
Ultimately, the choice between 0.030 flux core wire and 0.035 flux core wire depends on the specific application and the thickness of the metal being welded. It is important to choose the right size wire to ensure a strong and clean weld.
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