What to consider about the Best Price Mig Welder
Why buy the Best Price Mig Welder ?
Mig is an easy process to learn
Has better control on thinner metals
Can be relatively inexpensive
Mig is not suggested for metals above 3/16"
Can be used with all current inputs (110,220,440)
3 types of wire
1)Flux core -
Flux Cored Wire is Gasless
Wire is tubular with flux material contained inside shielding.
Works with dirty, rusty material
Good penetration, worst appearance
2)Flux core dual shield
Uses flux shielding AND gas shielding
either 75/25 Ar/CO2 or CO2, flux core wire is specifically made to weld with or without shielding gas be sure you have wire made for gas shielding.
Good penetration, better appearance
3)Solid core wire with gas shield
Cleaner welds with less slag to clean.
Average penetration, best appearance
Most commonly used
Common gasses include
CO2 - most penetrating/poorest appearance 75/25 - (Ar/CO2) good penetration/good appearance 92/8 - (Ar/CO2) poor penetration/best appearance
Consider applications for your welder
farm/ranch Construction home, auto body/repair general maintenance/repair
Welders designed for specific applications depending on;
- rated output - duty cycle - other features
Most applications of gas metal arc welding use a constant voltage power supply
As a result, any change in arc length (which is directly related to voltage) results in a large change in heat input and current.
A shorter arc length will cause a much greater heat input, which will make the wire electrode melt more quickly and thereby restore the original arc length.
This helps operators keep the arc length consistent even when manually welding with hand-held welding guns.
To achieve a similar effect, sometimes a constant current power source is used in combination with an arc voltage-controlled wire feed unit.
In this case, a change in arc length makes the wire feed rate adjust in order to maintain a relatively constant arc length.
In rare circumstances, a constant current power source and a constant wire feed rate unit might be coupled, especially for the welding of metals with high thermal conductivities, such as aluminum.
This grants the operator additional control over the heat input into the weld, but requires significant skill to perform successfully.
Alternating current is rarely used with GMAW; instead, direct current is employed and the electrode is generally positively charged.
Since the anode tends to have a greater heat concentration, this results in faster melting of the feed wire, which increases weld penetration and welding speed.
The polarity can be reversed only when special emissive-coated electrode wires are used, but since these are not popular, a negatively charged electrode is rarely employed.
Single-phase- 115 or 220 Volts
115 volt welders typically draw too much current to be plugged into a typical outlet. Dedicated circuits are best, regardless, be sure your outlet can carry the current (amperage) required !
A gas-powered, generator can supply power as well.
Four types of metal transfer
globular metal transfer is often considered the most undesirable of the four major GMAW variations, because of its tendency to produce high heat, a poor weld surface, and spatter.
The method was originally developed as a cost efficient way to weld steel using GMAW, because this variation uses carbon dioxide, a less expensive shielding gas than argon.
Adding to its economic advantage was its high deposition rate, allowing welding speeds of up to 110 mm/s (250 in/min).
As the weld is made, a ball of molten metal from the electrode tends to build up on the end of the electrode, often in irregular shapes with a larger diameter than the electrode itself.
When the droplet finally detaches either by gravity or short circuiting, it falls to the workpiece, leaving an uneven surface and often causing spatter.
As a result of the large molten droplet, the process is generally limited to flat and horizontal welding positions.
The high amount of heat generated also is a downside, because it forces the welder to use a larger electrode wire, increases the size of the weld pool, and causes greater residual stresses and distortion in the weld area.
Further developments in welding steel with GMAW led to a variation known as short-circuiting or short-arc GMAW, in which carbon dioxide shields the weld, the electrode wire is smaller, and the current is lower than for the globular method.
As a result of the lower current, the heat input for the short-arc variation is reduced, making it possible to weld thinner materials while decreasing the amount of distortion and residual stress in the weld area.
As in globular welding, molten droplets form on the tip of the electrode, but instead of dropping to the weld pool, they bridge the gap between the electrode and the weld pool as a result of the greater wire feed rate.
This causes a short circuit and extinguishes the arc, but it is quickly reignited after the surface tension of the weld pool pulls the molten metal bead off the electrode tip.
This process is repeated about 100 times per second, making the arc appear constant to the human eye.
This type of metal transfer provides better weld quality and less spatter than the globular variation, and it allows for welding in all positions, but generally the process is much slower than globular GMAW.
Another difficulty is maintaining a stable arc, because it depends on achieving a consistent and high short-circuiting frequency, which can only be accomplished with a good power source, suitable welding conditions, and significant welder skill. Like the globular variation, it can only be used on ferrous metals.
Spray transfer GMAW was the first metal transfer method used in GMAW, best suited for welding aluminum and stainless steel while employing an inert shielding gas and a relatively thick electrode.
In this variation, molten metal droplets (with diameters smaller than the electrode diameter) are rapidly passed along the stable electric arc from the electrode to the workpiece, essentially eliminating spatter and resulting in a high-quality weld finish.
However, high amounts of voltage and current are necessary, which means that the process involves high heat input and a large weld area and heat-affected zone.
As a result, it is generally used only on workpieces of thicknesses above about 6 mm (0.25 in).
Because of the large weld pool, it is often limited to flat and horizontal welding positions, but when a smaller electrode is used in conjunction with lower heat input, its versatility increases.
The maximum deposition rate for spray arc GMAW is relatively high; about 60 mm/s (150 in/min).
A more recently developed method, the pulse-spray metal transfer mode is based on the principles of spray transfer but uses a pulsing current to melt the filler wire and allow one small molten droplet to fall with each pulse.
The pulses allow the average current to be lower, decreasing the overall heat input and thereby decreasing the size of the weld pool and heat-affected zone while making it possible to weld thin workpieces.
The pulse provides a stable arc and no spatter, since no short-circuiting takes place.
This also makes the process suitable for nearly all metals, and thicker electrode wire can be used as well.
The smaller weld pool gives the variation greater versatility, making it possible to weld in all positions.
In comparison with short arc GMAW, this method has a somewhat slower maximum speed (85 mm/s or 200 in/min), and the process also requires that the shielding gas be primarily argon with a low carbon dioxide concentration.
Additionally, it requires a special power source capable of providing current pulses with a frequency between 30 and 400 pulses per second.
However, the method has gained popularity, since it requires lower heat input and can be used to weld thin workpieces, as well as nonferrous materials.