MIG is much more forgiving on very thin metal than stick welding, which can easily burn through thin material.
Welding is a necessity for most small farmers. Steel gates and fences crack, sheet metal needs patching on combines and other implements, three-point hitches need repair and the bucket on that skid loader should get some hard-surfacing to extend its life. In short, a welder keeps the farm running.
Traditional stick arc welders, often referred to as “buzz boxes,” have been the welders of choice for small farmers the world over. And for good reason. They’re inexpensive, portable, weld most metals found on the farm and can do it in virtually any weather condition.
The invention of wire welding, which includes metal inert gas (MIG) and flux cored arc welding (FCAW), has made welding faster, easier and more versatile. Wire welding replaces the fixed-length stick electrode, which must be replaced frequently, with a spool of wire fed through a welding gun. Because the wire is fed at a continuous rate, you don’t need to keep moving your hand closer to the weld as the stick burns off. It is often said that if you can draw a straight line, then you can wire weld.
A MIG/flux cored welder may not be the right investment for every small farm, though. If you have a stick welder in good condition that has been meeting all of your welding needs, it might not make sense to buy a MIG welder. On the other hand, if your stick machine needs replacing, you are just now looking into purchasing a new welder, or if you frequently need to weld metal that is too thin for your stick welder, MIG provides a very flexible and affordable alternative.
A Hobart Handler 140, which can weld up to quarter-inch material in a single pass, retails for around US$500, about $21 more than the top of the line Hobart Stickmate LX 235AC/160 DC, which is also rated to quarter-inch thickness in DC mode. The Stickmate can weld thicker material in AC mode, but it does not provide the smooth performance and easy arc starts of DC mode.
MIG welding uses a non-combustible gas, typically a mixture of 25 per cent carbon dioxide and 75 per cent argon, which flows through the tip of the welding gun and protects the weld from contamination by the surrounding air environment. The use of gas eliminates slag deposits that must be chipped off the weld, a major time saver if you need to make multiple passes on thick material.
Because the gas is exposed during the welding process, however, winds over 10 miles per hour will blow it away from the weld and result in a bad weld with porosity. That’s where self-shielded flux cored welding comes in.
Flux cored welding can be done using a traditional MIG machine and differs from MIG only in that the shielding is provided by a flux compound built directly into the wire. No external cylinder of gas is needed. With flux cored wire, you can weld in almost any environment. Flux cored welding does create slag, however, so if you’re welding in an indoor environment, MIG welding is the preferred process.
STICK VS. MIG
While stick welders are less expensive and more familiar for most farmers, stick welding does has it shortcomings in the modern shop. Stick welding thin materials may be difficult or impossible. Even skilled welders would hesitate before attempting to stick weld 18-gauge steel sheet metal. It takes a lot of skill to stick-weld aluminum. Stick welding leaves a lot of slag, which is messy and time-consuming to clean up. Stick is a slower process than MIG. That said, stick welders are more forgiving on dirty or rusty materials and better suited to outdoor conditions than MIG.
While you may be familiar with stick welding, MIG welding is the easiest process to learn. MIG welds light gauge material or thick plates, and it welds all common metals — carbon steel, stainless steel and aluminum. MIG welders work a lot faster — up to four times faster — and leave less waste. Fifty pounds of MIG welding wire yields 49 pounds of metal deposition, while 50 pounds of stick electrode rods yield approximately 30 pounds of deposition. Shortcoming of MIG is that it doesn’t work well on rusty metal and it doesn’t work well outside.
FLUX CORED TAKES MIG UP A NOTCH
Self-shielding flux cored welding is less affected by drafts and wind, thus better suited for work outdoors. It works as well as stick on rusty or dirty material. And with continuous wire feed, as with MIG, you can minimize arc starts and stops when making long welds.
Flux cored welding also provides deep penetration for welding thick sections. And it eliminates need for a shielding gas cylinder, which increases portability.
MIG WORKS WELL ON SHEET METAL
If you wish you could do more sheet metal repair, that’s all the more reason to look at a MIG welder. MIG is much more forgiving on very thin metal than stick welding, which can easily burn through thin material.
Stick, MIG and flux cored welding can all weld thick metal, but sometimes you will need to perform multiple passes to obtain a strong weld. In those instances, you would save considerable time with MIG because you won’t need to chip off the slag after each pass.
The amperage rating on a welder is a useful guide for determining the thickness a machine can weld in a single pass. The Hobart Handler 140, for example, puts out up to 140 amps, allowing it to weld quarter-inch metal in a single pass. Machines with higher amperage ratings can weld thicker materials.