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
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.
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™
