MIG Welding Machine Buying Guide

Use these facts and diagrams to help you make the right choice when buying a MIG welding machine

MIG Welding Modes of Transfer

Ideal for thin material
Works for out-of-position work
Offers open root capability
Risks poor fit-up
Produces some spatter
Poor penetration on thicker materials
Limited use on aluminum

Produces high amount of spatter
Has potential for incomplete penetration
Generally not recommended

Boasts high deposition
Results in good fusion, penetration & bead appearance
Accommodates large diameter wires
Produces very little if any spatter
Used only on material ⅛″ and thick
Works best in the flat and horizontal position
Good fit-up is always required since there is no open root capability

Produces high amount of spatter
Has potential for incomplete penetration
Generally not recommended

Amperage

Rule of Thumb = 1 ampere for every 0.001″ of material ⅛″
Material = 0.125 = 125 Amps

Wire Size

How to determine the correct size wire

Determine the ballpark amperage for the material you are welding using the rule of thumb (0.035 dia. is the most common).
Reference the manufacturer's wire data sheet. The wire data sheet has an amperage range for each wire size.
Choose a wire size. Your ball park range should fall near the middle of one of the amperage ranges on the wire diameter chart.

Determining Wire Feed Speed (WFS)

Once wire size and amperage have been determined, the correct WFS also needs to be determined.
The correct WFS needs to be determined
Use this rule of thumb:

Inches per minute needed per amp

Calculating Wire Feed Speed (WFS)

1 ampere for every 0.001 thickness
⅛″ material = .125 = 125 amperes

Wire Burn Off:
0.023 – 3.5″ wire/amp – 125 amps = 437 IPM
0.030 – 2″ wire/amp – 125 amps = 250 IPM
0.035 – 1.6″ wire/amp – 125 amps = 200 IPM
0.045 – 1″ wire/amp – 125 amps = 125 IPM

An example of how to determine wire feed speed in inches per minute (IPM) is below. A wire diameter size 0.035″ is chosen to weld on ⅛″ steel material. Use a "ballpark" amperage setting of 125 amps.

125 amps x 1.6 wire feed speed per amp = 200 IPM required wire feedspeed setting

Pick your power and portability

What should I know about duty cycle?
Duty cycle is the amount of time during a 10-minute period that the welder can continuously operate at its rated output without causing heat damage to the system. For example, a Millermatic^® 252 has a 60 percent duty cycle at 200 amps of DC output. It can weld for six minutes out of 10 and then needs to cool for the remaining four minutes.

How much welding or cutting output power do I need?

Light industrial products are suitable for the home hobbyist or occasional user. Designed to be easy to operate, affordably priced and typically have a 20 percent duty cycle and rated output of 230 amps or lower.
Industrial products are suitable for applications that do not require high-volume production and typically have a 40–60 percent duty cycle and/or rated output of 300 amps or lower. Appropriate choice for professional welders.
Heavy industrial products typically have a duty cycle of 60–100 percent and a rated output of at least 300 amps, making them suited to high-volume production and/or welding of thicker materials. Designed with the arc characteristics and product features professional welders demand for code-quality work.

Note: Units listed in more than one classification share attributes of both.

Generator power
Out in the field, you may need an engine-driven welder/generator to supply 120 or 240 VAC power to run tools, lights and to start motors. Miller engine drives are packed with power and the larger units even offer option packages that add 10 to 20 kW of generator power.

What kind of input power do I have available?
Out in the field, you may need an engine-driven welder/generator to supply 120 or 240 VAC power to run tools, lights and to start motors. Miller’s engine drives are packed with power and the larger units even offer option packages that add 10 to 20 kW of generator power.

Single-phase products require single-phase input power, typically found in homes and garages.
Industrial products require three-phase input power which is common in industrial settings, but shops can be specially wired to supply three-phase, industrial power. For locations where a three-phase electrical hookup is available.
For locations where an electrical hookup is not practical, consider a gas or diesel-powered, engine-driven welder/generator to supply welding and generator power.

Is portability needed?
Can you bring the work to the machine, or does the machine need to go to the work? Check the Product Guide pages for types of portability:

Shoulder strap, handles, running gear, carts, etc.
Many engine-driven welding generators fit in the back of a pick-up truck, enabling them to be driven to wherever the welding is needed. Heavy-duty trailers are also available for engine drives.

Spooled Wired Application Guide

Suggested Airgas Shielding Gases

Small Machines – Mild Steel Applications

Argon/CO₂ mix 75/25 industrial grade

Available in various cylinder sizes

ARCAL Flux

Only available in size 300 cylinders

Mid-size Machines – Mild Steel Applications

Argon/CO₂ mix 75/25

Various size cylinders
Will allow short circuit transfer only

ARCAL Flux

Only available in size 300 cylinders

ARCAL Force

Will allow short circuit and spray transfer
Only available in size 300 cylinders

Mid-size Machines – Stainless Steel Applications

ARCAL M12 He35

Will allow short circuit and spray transfer
Only available in size 300 cylinders

ARCAL Chrome

Mid-size Machines – Aluminum Applications

Argon industrial grade

For all thickness below ¼″
Available in various cylinder sizes

ARCAL Prime

For all thickness above ¼″
Only available in size 300 cylinders

ARCAL He20

For all thickness above ¼″
Only available in size 300 cylinders

ARCAL shielding gases are equipped with either SMARTOP™ or EXELTOP™

Welding Wire/Method Recommendations

Classification Systems

Graphic of AWS MIG ER70S-6 classification system

Graphic of AWS MIG ER308L classification system

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