Items of importance when GMAW welding

Mig Welding Parameters 11/22/2018 Mig Welding Parameters The 2 primary welding controls Voltage Control Wire Feed Speed (amp) Control Set them before you start welding. Mig Welding Parameters The 2 primary weld controls in Mig welding are… Voltage Wire Feed Speed (amps) Voltage is almost always displayed on your power supply. Some wire feeders are able to display and adjust voltage. Wire feed speed is adjusted at the wire feeder. It controls current which is measured in amps and is often displayed on the power supply. These are the 2 main weld controls and when you understand how, when and why to set them you will be able to control and Master the Mig welding process.

Amperage is Wire Feed Speed The wire feed speed controls the amperage. An increase in wire feed speed increases the amperage and penetration while welding. Decreasing the wire feed speed decreases the amperage and penetration while welding. IPM is Inches Per Minute.

Wire feed speed Too Fast Too Slow

How much wire feed speed (amperage) do I need to use?

???? Well you could find the information in an owners manual, on a chart, or in a book, or under a panel on the welder or ask your instructor or….. Learn another way. Check this out! NEXT SCREEN

Material thickness determines amperage. As a guideline, each 0.001 inch of material thickness requires 1 amp. Example 1/8in thick = 0.125 in. = 125 amps. Use the steps chart**** Your Wire diameter. The Constant factor. Wire feed speed. IPM

Let’s try it out. You are going to weld ¼ inch steel. What is ¼ of an inch in a decimal?____ You will use 0.035 diameter wire. What is the constant factor? _______ What should I set the wire feed speed to____ . What is IPM?________ (we are not talking about integrated pest management).

Now lets set the needed Voltage. Click for more information

???? Well you could find the information in an owners manual, on a chart, or in a book, or under a panel on the welder or ask your instructor or….. Learn another way. Check this out! NEXT SCREEN

Sweet Spot Voltage While one person welds on scrap metal, an assistant turns down the voltage until the arc starts stubbing into the work piece. Record the voltage. Start welding again and have an assistant increase the voltage until the arc becomes unstable and sloppy. A voltage midway between these two points provides a good voltage to weld at.

What does VOLTAGE affect? Increasing voltage increases arc length and the fluidity of the weld pool (more wetting out). Higher voltages produce a longer arc length and a flatter weld bead profile. Decreasing voltage decreases arc length and the fluidity of the weld pool (less wetting out). Lower voltages produce a narrow, "ropey" bead.

Too high or too low voltage Too high a voltage for any Wire Feed Speed causes the electrode to burn back to the contact tip. Low voltage causes difficult arc starting, spatter, or stubbing of the electrode on the base metal.

6 things (you) the welder controls after the arc is initiated: Electrode Extension (stick-out). Electrode Work Angle. Electrode Travel Angle. Direction of Travel. Travel Speed. Electrode Oscillation.

Thing 1. Electrode extension (stick-out) Electrode extension and stick out. Stick out is the distance the electrode sticks out from the contact tip either before you start the weld or while welding. Typical electrode extension for short-circuit welding is approximately 3/8 inch.

Changing the electrode extension. *With the voltage and Wire Speed unchanged. If the GMAW gun is moved away from the work, the result is a longer electrode extension and a slight reduction in the welding arc current (amperage).

Electrode extension Clip Too Much or Too Little

Thing 2 & 3. The electrode work and travel angle. Work angle refers to the GMAW gun position in relation to the workpiece. Travel angle refers to the angle of the welding gun in the direction of travel. Proper welding angles are critical to make satisfactory welds.

The Work angle is at a 45° angle between the top and bottom base metal, and about 5°–15° pointing in the direction of travel. Direction of travel

On groove joints the work angle is perpendicular to the base metal or at a 90° angle and about 5°–15° pointing in the direction of travel. Direction of travel

WATCH THE PUDDLE The welding arc and molten weld pool are influenced by factors, such as gravity, and weld position. The welder must always observe the weld pool and adjust the work angle to position the weld pool for the best weld bead placement and quality.

Thing 4. Direction of travel This has a significant affect on weld bead shape, and penetration.

Backhand technique Also referred to as a drag or pull technique, results in the most penetration; the weld gun is directed 5°–15° back into the weld opposite the direction of travel. The technique also produces a narrower, more convex weld bead.

Forehand Technique Also referred to as a push technique, the weld gun is pointed 5°–15° in the direction of travel. This technique produces a flatter weld and slightly less penetration.

Work Angle & Push or Pull information

Thing 5. Travel Speed One of the greatest effects the welder can have on the weld puddle and the depth of penetration is travel speed! Travel speed refers to the speed the weld bead travels down the workpiece or weld joint, in inches/minute. Movie clip

YOU The welder controls travel speed, making sure that the electrode stays in the leading edge of the weld pool (think of it as heat energy placement). The welding arc will sufficiently heat the base metal, and the arc force mixes the filler metal with the melted base metal.

Travel speed Too fast A Too fast a travel speed will not heat the base metal enough for adequate penetration and fusion to occur. Filler metal will pile up on the base metal rather than melting and mixing with the base metal. This creates a high, convex, and ropy appearing weld bead that tends to have a ripple pattern that is long sided and v-shaped. Movie clip

Travel speed Too slow A Too slow a travel speed prevents the arc from heating the base metal by forming an insulating layer between the arc and the un-melted base metal. The arc heat energy is dissipated in the molten weld pool instead of heating (melting) the cold base metal, resulting insufficient penetration, insufficient fusion, and cold lap. Movie clip

Cold Lap/ Lack of Fusion Producing a large weld bead does not guarantee a stronger weldment.

Travel speed correct Movie clip

Thing 6. Electrode oscillation is The movement of the electrode in a pattern that is side to side or circular in motion. Patterns help spread out the weld the way you would spread peanut butter on bread. It makes things smooth and uniform.

About patterns Oscillation and travel speed often go hand in hand. Oscillation patterns influences the shape of the puddle.

Electrode location. It is very important to keep the electrode at the leading edge of the puddle, and some patterns do not promote staying on the leading edge. Some of the arc heat energy is dissipated in the molten weld pool instead of heating the cold base metal which could result in insufficient penetration, insufficient fusion, and cold lap.

Remember Electrode position Arc must be on leading edge of weld pool to assure penetration and fusion

For most GMAW applications, the welder will produce fewer discontinuities if welding is done in a straight line with the backhand or forehand technique. Welding in a straight line will decrease bead width, but weld penetration will increase.

The electrode should be at the leading edge of the puddle so the arc heat energy is focused into the weld joint. Some electrode movements don’t allow that. Making a weld bead by using oscillation will increase bead size, but weld penetration will decrease.

GMAW Procedure review Review clip

Practice, Practice, Practice! My father taught me that the only way you can make good at anything is to practice, and then practice some more. Practice correct principles and you will be successful.