Industrial gases & Welding products
Pure gases & specialty mixes
FAQ
Selection charts
Certificates of conformance
Material Safety Data Sheets
Technical Sheets
Data book
Brochures
Promotions
Advertising
Contest
Go green
Metal fabrication
Automotive
Entertainment
Plumbing/HVAC
Wineries
Restaurants/bars
Technical Information | FAQ | GMAW
Gas Metal Arc Welding or MIG Welding (GMAW)

  1. What difference is there between a regulator flow meter and a regulator flow gauge?
  2. What gas flow rate should I use for a specific thickness of material?
  3. What difference is there between GMAW MIG and flux core welding with gasless wire?
  4. Why weld with a GMAW MIG versus metal core wire?
  5. How do I set my welding parameters, wire feed speed, voltage, etc to weld with a BlueshieldTM 8 gas?
  6. What is the difference between a BlueshieldTM 8, CO2 and ALMIGTM gas?
  7. How many hours can I weld with a size 16 ALMIGTM cylinder?
  8. Can I use my MIG welder to weld Aluminum?
  9. Can my MIG 110 be used to weld aluminum?
  10. What is Auto Regulation and what are its advantages?
  11. What diameter of MIG wire should I use?
  12. What is the difference between a heat switch and a potentiometer or continuous voltage control on some MIG machines?
  13. How thick can I weld with my small MIG welder?
  14. Why is my wire having a hard time coming out of the gun?

1-What difference is there between a regulator flow meter and a regulator flow gauge? (top)
There is essentially no difference as they flow measure flow in standard cubic feet per hour or liters per minute. The regulator flow meter is a pressure regulator with a calibrated flow tube attached to it. The low-pressure side of the regulator is set to match the calibrated inlet pressure of the flow tube. A regulator flow gauge is a pressure regulator with its low pressure gauge calibrated in flow measurements. The regulator flow gauge has a small-calibrated orifice in its outlet.


2-What gas flow rate should I use for a specific thickness of material? (top)
The flow rate is a function of the welding parameters and the nozzle dimensions. A good recommendation is 1 Liter/minute of flow for every millimeter of opening of the nozzle in the welding gun. This translates into roughly 7 cfh for every 1/8 inch of nozzle opening. For example if the nozzle is 1/2 inch, this is equal to 4/8 inch. Therefore the required flow is a minimum of 4 X 7scfh or 28 standard cubic feet per hour. If porosity is noticed, increase slightly the gas flow rate. When welding in drafty environments or at high welding travel speeds shielding gas flow rates of 50 scfh are not uncommon.


3-What difference is there between GMAW MIG and flux core welding with gasless wire? (top)
With the gasless flux core wire, no cylinder of shielding gas is required. The welds produced with the gasless wire are covered with a protective layer of slag. Typically the spatter level is elevated. The gasless flux core wire welds easier on dirty rusty material whereas a MIG under the same conditions will produce porosity or pin holes. The smallest diameter of gasless flux core wire available is .030 inch or 0.8 mm. The smallest diameter of MIG wire is.023 inches or 0.6mm and you can weld at lower amperage with the smaller diameter MIG wire so it is easier to weld thin material such as auto body steel. Be certain to select the proper welding polarity for the wire you are using. GMAW (MIG) wire use DC+ (electrode positive) and Gasless FCAW wires typically run on DC- (electrode negative) polarity. Selecting the wrong welding polarity will result in an extremely harsh arc with excessively large spatter.


4-Why weld with a GMAW MIG versus metal core wire? (top)
MIG wire is a lower cost for equivalent diameter and packaging when compared to metal cored wire. MIG wire is solid whereas the metal core wire is a tubular wire or is a soft-shelled wire. The metal core wire may be more difficult to feed through the welding gun particularly in small diameters such as 0.035" (0.9mm). The metal core wire runs smoother on mill scaled or rusty plate and is more tolerant of oil or grease contamination on the plate all while handling gaps easier than the MIG wire. Overall, the metal core wire is more user friendly than the MIG wire.


5-How do I set my welding parameters, wire feed speed, voltage, etc to weld with a BlueshieldTM 8 gas? (top)
The majority of small MIG machines have a parameter chart or table inside of the cover of the machine. Consult this chart when installing the MIG wire.


6-What is the difference between a BlueshieldTM 8, CO2 and ALMIGTM gas? (top)
CO2 is an unstable gas which tends to produce spatter and smoke while welding. At the same time the CO2 tends to increase penetration. BlueshieldTM 8 is a mixture of 75%Argon-25%CO2. The argon tends to stabilize the arc, reducing spatter. The weld is also smoother. ALMIGTM is a tri-mix gas containing 91%Argon-5%CO2 and 4%Oxygen. Because of its high argon content it tends to penetrate less making it an excellent choice when welding thin gauge material such as auto bodies.


7-How many hours can I weld with a size 16 ALMIGTM cylinder? (top)
The Air LiquideTM Product Catalogue lists our cylinder gases, cylinder size and the cubic content of the cylinder. The ALMIGTM cylinder contains 101.34 cu feet of gas. If the welder is welding with a flow rate of 20cubic feet per hour he has approximately 5 hours of continuous welding possible (101.34 cubic feet divided by 20cfh or the flow rate). This method can be used for any size cylinder and flow rate. Cylinder capacities are found in the catalogue. The customer may know his flow rate or you can estimate his flow rate.


8-Can I use my MIG welder to weld Aluminum? (top)
Yes you can but you require an inert gas such as Argon or ALTIGTM. The drive rolls used should be "U" grooved drive rolls and the gun liners and feed guides made of Teflon or nylon. The gun length should be as short as possible and be kept as straight as possible. 5356 aluminum wire feeds better than the 4043 type because it is stiffer. If much Aluminum is going to be welded you should look at whether a spool gun or a push-pull aluminum gun can be adapted to the MIG unit.


9-Can my MIG 110 be used to weld aluminum? (top)
Yes! Small diameter wire of . .035 diameter or 0.9mm should be used. The alloy 5356 is harder than the 4043 alloy so should feed easier. Nylon liners and guides should be used in the gun and the gun should be kept as straight as possible. Excessive coiling or binding of the gun conduit or liner causes excess friction and feeding problems. Most small feeders come equipped with "V" groove drive rolls for welding with steel MIG wires. For Aluminum welding, "U" groove drive rolls if available should be used. Alloy 4043 is sometimes recommended because even though it is more difficult to feed through the weld gun because it is softer, it melts at lower amperage.


10-What is Auto Regulation and what are its advantages? (top)
Auto regulation is a feature of some MIG machines that permits easier set up of parameters. With auto regulation the arc voltage will automatically increase as wire feed speed is turned up. The operator tunes his machine in terms of parameter and if he turns up the wire feed speed, the voltage will automatically be raised and the operator can then just fine-tune the voltage setting.


11-What diameter of MIG wire should I use? (top)
If you were typically welding material less than 1/8 inch thick, a 0.6mm diameter or .023-inch wire would work well especially on the thinnest gauges. The 0.8 mm (0.030) diameter works well on thickness of 1/16 to 1/4 inch in thickness. The 0.9 mm (0.035) works well on thicknesses of 3/32 and up.


12-What is the difference between a heat switch and a potentiometer or continuous voltage control on some MIG machines? (top)
The wire feed speed in MIG welding controls amperage or welding heat. The higher the wire feed speed, the more amperage is required to melt the wire and this higher amperage penetrates or digs more into the base material. The voltage control can be a knife switch with specific setting or it can be continuous. With a knife switch voltage control you are limited to specific voltage settings. For a machine with 4 settings (1,2,3,4) the #4 setting will give the highest voltage or arc length. If you set the machine at #4, you have to turn the wire feed speed up to balance the arc or get the proper arc length. Continuous voltage dials allow more flexibility in adjusting the arc length as you an fine tune them.


13-How thick can I weld with my small MIG welder? (top)
A general rule of thumb would be as follows. For every ampere of output of the machine you can easily weld .001 inch of steel or 1/1000inch of thickness. For example a 130 amp machine will weld .130 inches thick with relative ease. Since 1/8 inch is .125 inches we will say 1/8 inch. If we double this thickness we run into problems so 1/4 inch would be the maximum. For a 250-amp machine we could easily weld .250-inch thick material and an effective maximum would be .500 inches or 1/2 inch. Since the larger machines have more power thicker material could be welded by using a multi pass technique or by making several small welds.


14-Why is my wire having a hard time coming out of the gun? (top)
If the wire is having a hard time coming out of the gun, you are having feeding problems. The inlet guides, liners and contact tubes all have a tolerance. Make sure that you have the correct size of guides, liner and tip. With time the liners and tips can become clogged with dirt. A tip can become plugged. Take the tip out of the gun and try to feed the wire through the gun by squeezing the gun trigger with the gun liner as straight as possible. If the wire feeds through without the tip, you know that the problem was the tip. Check for tip size and plugging. Loosen the drive rolls totally and try to pull the wire through the gun. If you can't pull it through the gun, chances are that the liner is plugged. If you can pull it though the gun, put the correct size contact tube in the gun and slowly increase the drive roll pressure while depressing the gun trigger or wire jog button on the machine. Use just enough pressure to feed the wire as too much pressure will distort the wire and cause feeding problems.

Copyright - Air LiquideTM 2006 All rights reserved.