GMAW Set up to run a bead

GMAW easy to learn? Of all the welding processes, gas metal arc welding is the easiest to learn. However, setting up a GMAW system isn't quite so straightforward. Improper setup can lead to some major problems.

Get your mind in the game! But by being mentally engaged when setting up, you can ensure you have the information you need to perform the weld correctly the first time.

1. The best scenario of bad welding If machine settings are incorrect, the welder pulls the trigger and produces an obviously bad weld. This result (bad weld) is easy to notice and be fix before it goes out the door (to the customer).

2. The worst scenario of bad welding A welder starts welding with an improperly set up machine and doesn't know it. Welding problems, penetration or fusion, or others are in the weld but un-seen. The part makes it out the door (to the customer) and fails in service.

Discuss the 2 scenarios of bad welding What impact could this have: On your JOB? On your BUSINESS? Who is responsible for quality control?

A brief check before starting to weld will reduce bad welds. Inspect the welding torch, cable assembly, the welding gun and nozzle for excess spatter. Clean or replace parts if necessary. Make sure the correct size tip is used and that it is clean and tight.

In GMAW, paying attention to the little things matters. It is like a daily driver and a race car driver. The commuter usually opens the door, turns the key, and drives off. The race car driver and his team go through a list to ensure all systems are go. EVERY TIME.

What are you going to do? Decide what material you are going to weld. Decide how thick the Material is. Decide what type of weld and joint design. What position is it to be welded in? There are many things to consider.

Types of Welds Groove Bead Fillet

*Welding Positions Welding is often done on structures in the position in which they are found. Techniques have been developed to allow welding in any position. Some welding processes have all-position capabilities, while others may be used in only one or two positions.

There are four basic welding positions All welding can be classified according to the position of the workpiece or the position of the welded joint on the plates or sections being welded. The Face and the geometric center of the weld bead gives reference to what position the joint is in.

AWS Position designation. 1 is for the flat position. 2 is for the horizontal position. 3 is for the vertical position. 4 is for the overhead position

AWS joint design designation. F is for a fillet weld. G is for a grove weld.

By using the Position Number(1,2,3,or 4) and the Joint Letter (G or F) together it is like an abbreviation to give you information about what to weld and where.

Groove welds The number designates the position The G designates a Groove weld

Fillet welds The number designates the position The F designates a Fillet weld.

Example: 3F or a 3G gives a picture to the welder of the position and joint design that needs to be welded. A mention of direction: up, uphill, down, or down hill, refers to weld progression.

How much Amperage do I need? (Wire Feed Speed) Either you already know what to set the Feed Speed at. Or ask your instructor for the Wire Feed Speed to use. Or determine the Feed Speed using the 1 amp per .001 metal thickness method. Remember Increase wire speed = Increase amps Decrease wire speed = Decrease amps

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

What should my Voltage be set at? Either you already know what to set the voltage at. Or ask your instructor for the voltage to use. Or determine the voltage from using the sweet spot method.

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.

Prepare the metal before welding Even if you are the world’s best welder, you should always have a clean joint. There is nothing that you can do to fix a weld bead if the joint was dirty(maybe grind it out?). Remove rust, scale, burned edges and coatings. If you leave junk in the joint then you get junk out of the weld. Got it! Clean your metal clip

Nozzles Banging the side of the nozzle against the worktable to remove spatter is not good for the gun components and nozzle. Those nozzle dents may even cause weld problems. They can alter the delivery of your shielding gas.

Check and clean A small rat-tail file works for removing spatter (left) only when the nozzle and insulator are separate pieces. Welpers (right) are a good tool for cleaning the nozzle, especially if the nozzle and insulator are one piece.

Look at the contact tip orifice. Are there gaps around the wire? Is it out of round or melted in any way? The wire needs to fit inside the contact tip like a glove. Worn out of round. Need to replace

Avoid Spatter Anti-spatter materials can help keep MIG parts clean, Spray or Dip (But use sparingly). The best way to reduce spatter is to have your settings dialed in correctly. Most problems are from either not having enough voltage or having too much wire speed. Also, make sure the surfaces you are welding are clean, dirty material increases spatter.

Spatter on your work A light spray over the weld area will prevent most spatter from sticking to the surface, a light swipe with a wire brush will remove virtually all spatter.

Poor welders keep using a bad contact tip even though they could produce better welds if they just took a few seconds to replaced it. A worn or spatter-covered contact tip should be replaced with a new one. Check that the contact tip is centered and tightened. A loose contact tip can cause an erratic arc.

GMAW Set Shielding Gas flow. CFH Is the Shielding gas connected the correct gas for what you are welding? Check a chart or with your instructor for the correct setting CFH. Pull trigger to get gas flowing then check or adjust flow regulator. Shielding gas clip

Cables Make sure the weld gun lead cable isn't wrapped tightly or kinked. Keep the lead from getting ran over or smashed. This can cause excessive wear or damage your liner and cause feeding issues.

Avoid the nubs! To get the proper electrode extension, or stickout, welders sometimes point the gun at the workpiece or the table, pull the trigger, and melt a bit of wire off, leaving wire nubs sticking up on the table or workpiece. This is just sloppy work practice and very unprofessional. Nubs on the workpiece require extra clean up.

During setup make sure your welding tools and equipment are in their place. Use the wire cutters and cut the wire to the correct length. As an added benefit, cutting the welding wire at a 45-degree angle will promote a faster arc start as well.

Running a Bead- Push or Pull? There's an old saying that goes, "If there's slag, then you drag," which means use the drag technique for Stick and Flux Cored welding. When GMAW mild steel you can use either the Push or Pull technique.

Push or forehand technique Pushing the gun away from (ahead of) the weld puddle usually produces slightly lower penetration and a wider, flatter bead because the arc force is directed away from the weld puddle. **Pushing usually offers a better view of the weld puddle and enables you to better direct wire into the joint. Movie Clip

Drag or backhand technique The welding gun is pointed back at the weld puddle and dragged away from the deposited metal. Dragging typically produces deeper penetration and a narrower bead with more buildup. Movie Clip

Stringer Bead Normally, a single stringer bead is satisfactory for most narrow groove weld joints. Steady Movement Along Seam

Weave on not? Patterns help spread out the weld the way you would spread peanut butter on bread. It makes things smooth and uniform. Oscillation and travel speed often go hand in hand and influence the shape of the puddle. Oscillation has an effect on Penetration

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

Weave Bead For wide groove weld joints or bridging across gaps, a weave bead or multiple stringer beads works better. Side To Side Movement Along Seam

For lap and T-joints, Fillet Welds Manipulating the gun to create a series of small ovals provides good welding coverage. Be careful not to move too far back into the weld puddle or else fusion problems may occur.

For Butt Welds, Groove joints Manipulate the gun so that the electrode moves in a ’Z’ pattern while traveling along the workpiece. This pattern produces a flatter weld, spreading the molten weld puddle evenly across the joint.

Some review and information Good review information

Starting an arc is not difficult. Every thing is set and ready to go, you have checked on it. Hold tip 1/16” to 1/8” from work piece Gun angle should be 5-15°in the direction of travel. Pull the trigger on the welding gun to start the arc. Make the weld!

Finishing the Weld by Filling the weld Crater Craters can form at the end of a weld. If they are not filled, they create a stress point, which can lead to cracking. This requires the user to quickly trigger the gun again to fill in the crater. Filling the crater Clip

Restarts After you can run a bead pushing or dragging, you should practice restarts. Restarts are when you have stopped welding and need to continue the same bead. The more restarts you do, the better welder you will become.

The crater is where you stopped welding. The arc force cut into the steel, but you didn’t leave enough filler metal to fill the crater. A restart should be done correctly if the weld is to be continued.

1. Restart in the last weld’s crater 1. Restart in the last weld’s crater. When you start at the end of the crater, you preheat the base metal. 2. Move the arc back against the bead, hesitate slightly to burn into the existing bead. 3. Then continue in the direction you were traveling. 2. After a while you should be able to do a restart so that it ties in inconspicuously and contains no gaps that can weaken the weld. 1. 3.

Shutting Down the Equipment Stop welding and release gun trigger. Shut off welding machine and wire feeder. Hang up welding gun and cable assembly. Wire brush weldment for evaluation. Clean your work area.

Your technique needs to: Be what works right for you. Be correct to the Welding code or the weld procedure you are following. Produce correct welds, that you can Produce each time you weld.

Practice + practice + practice Nobody likes practice, but what's worse ? practicing, or sucking at something!

Discuss the previous slide as a class