Chapters 11 & 17

How is an outside corner joint assembled?

20. Place one piece of metal flat on the table and hold or brace the other piece of metal horizontally on it. Then, tack weld both ends together. After that, set up the plates and add two or three more tack welds on the joint as required. Finally, starting at one end, make a uniform weld, add filler metal as required.

What causes the electrode to bird nest?

A "bird nest" can occur when the wire electrode does not properly exit the out-feed side conduit and tangles up in front of the rollers.

Why must you always wind the wire tightly into a ball or cut it into small lengths before discarding it in the proper waste container?

Because the wire could become caught in power source filter screen, presenting an immediate danger of electrical shock to the welder.

What must be done with the weld craters? why?

Fill each weld crater adequately to prevent crater cracking.

How is filler metal added for a 3F weld?

Filler metal should be added along the top edge of the weld pool.

What are the advantages of making vertical down welds?

High travel speeds, thin sections of metal can be welded due to shallow penetration, good bead appearance.

What are the advantages of using CO2 for GMA welding on steel?

Higher travel speeds, better penetration, and good mechanical properties.

Which incorrect welding parameters does stainless steel show clearly?

If there is a problem with the welding parameters, the most common indication is that the weld bead will change to a darker color due oxidation.

When making a vertical weld and it appears that the weld metal is going to drip over the shelf, what should you do?

Increase the weave length, increase the electrode extension, or stop and start the welding current.

How can spatter be controlled on the gas nozzle when making overhead welds?

Increased electrode extension, sharper gun angle.

What can cause undercutting on a 3F tee joint?

Keep the arc on the back plate and add filler metal to the weld pool near the side plate.

What is the advantage of using a feed roller pressure that is as light as possible?

Light roller pressure prevents bird nesting if cloth or hoses become caught in the rollers.

Why must all fittings and connections be tight?

Loose fittings can leak and add resistance to the welding circuit, reducing welding efficiency.

How can small weld beads be maintained during overhead welds?

Lower current settings, faster travel speeds, increasing the electrode extension, pushing the weld pool.

What is mill scale?

Mill scale is an oxide layer formed on hot-rolled steels.

How can the rod be freed if it sticks to the plate?

Move the torch towards the filler rod until it melts free.

What active gasses are used with argon for GMA welding on steel

Oxygen and CO2.

What parts should be activated by pressing the gun switch?

Power source relay, feed relay, gas solenoid, and feed motor.

What should be done if someone comes in contact with a cleaning chemical?

Refer to the MSDS for the proper corrective actions.

What is the advantage of adding oxygen or CO2 to argon for welds on steel?

Stabilizes the arc, promotes favorable metal transfer, and reduces spatter.

What holds the weld in place on 4F weld?

Surface tension.

How is the amperage adjusted on a GMA welder?

The amperage is set by changing the wire-feed speed.

What helps hold the weld in place on a 2F lap joint?

The bottom plate acts as a shelf to support the molten weld pool.

benefit does a welding wires cast provide?

The cast helps make good electrical contact as it passes through the conduit tube.

What must be done to a shielding gas cylinder before the valve protection cap is removed?

The cylinder must be chained securely in place.

What may happen to the end of an aluminum welding rod if it is held to close to the arc?

The end of the filler metal rod may melt before it can be added to the molten weld pool.

why must the end of the filler rod be kept in the shielding gas protective zone?

The end of the filler rod must be kept in the shielding gas protective zone to keep it from oxidizing.

How should filler metal be added to the molten weld pool?

The filler rod can be held lightly in the leading edge of the weld pool or it can be dipped into the center of the weld pool.

How is it posable to control a large aluminum weld bead?

The molten weld pool has high surface tension, allowing large weld beads to be controlled easily.

What is the effect on the weld does changing the welding angle from dragging to a pushing angle?

The penetration and build up decreases.

What determines the correct current for a GTA weld?

The power to the machine is exactly correct, the lead length is very short, all connections are perfect with no resistance, the arc is exactly the right length, and the remote current control is in the full-on position.

What should the welder watch if the view of the weld is obstructed by the gas nozzle?

The trailing edge of the molten weld pool.

What effect on the welding current does increasing the wire feed speed have?

The welding current increases.

Why should the feed roller drag prevent the spool from coasting to a stop when the feed stops?

The wire can snag easily, and when the wire feed restarts the slack in the wire can cause a jolt, stopping the welding process momentarily resulting in discontinuities in the weld.

Why is the shielding gas valve "cracked" before the flow-meter regulator is attached?

To blow out any dirt or debris.

When should the minimum gas flow rate be increased?

To weld in drafty areas or for out of position welds.

What effect does torch angle have on the shielding gas protective zone?

Torch angle changes the shape of the shielding gas protective zone. If the torch angle becomes too extreme, the protective zone may become so distorted that the weld may be no longer protected from contamination.

What can cause tungsten contamination?

Tungsten contamination can occur when the tungsten comes in contact with the molten weld pool or the end of the filler rod.

What type of porosity is commonly caused by mill scale?

Uniformly scattered porosity.

What can be done to limit oxide formation on stainless steel?

Use a chill plate or make the bead with as low of a heat input as possible.

What happens to the weld as the electrode extension is lengthened?

Weld penetration is reduced and build up increases.

What items make up a basic semi-automatic welding system?

Welding gun, gun switch circuit, conduit-welding contactor control, electrode feed unit, electrode supply, power source, shielding gas supply, shielding gas flow meter regulator, shielding gas hoses, and both power and work cables.

List the factors that effect the gas flow setting for GTA welding.

Wind or draft speed, Nozzle size used, tungsten size used, amperage, joint design, welding position, type of metal welded.

What can prevent both side of a stainless steel tee joint from being welded?

carbide precipitation