Chapter 4 and 5 Welding Final

Advantages of Short Circuiting Transfer (GMAW-S)

-All position capability (flat, horizontal, vertical-up, vertical-down, and overhead) -Handles poor fit -up well, and capable of root pass work on pipe applications -Lower heat input reduces weldment distortion -ease of use -Higher electrode efficiencies (93% or greater)

Axial Spray Transfer ADVANTAGES

-High electrode efficiency of 98% or more -High deposition rates -absence of weld spatter -Excellent weld fusion - good with semi automatic, robotic and hard automation applications

Axial Spray Transfer LIMITATIONS

-High radiated heat/ very bright arc require extra welder and bystander protection -Restricted to flat and horizontal welding positions -welding fume generation high -outdoor axial spray transfer requires use of windscreens - Shielding used to support Axial Spray Transfer more costly than 100% CO2

Limitations of Globular Transfer

-Higher spatter levels - costly cleanup -reduced operator appeal -prone to cold lap or cold shut incomplete fusion defects - costly repairs -weld bead shape is convex and welds exhibit poor wetting at the toes -High spatter level reduces electrode efficiency to 87-93%

Advantages of Globular Transfer

-Inexpensive CO2 shielding gas, used with Argon/CO2 blends -can make welds a very high travel speeds -inexpensive solid metal cored electrodes -equipment inexpensive

Limitations of Short Circuiting Transfer

-poor welding can result in incomplete fusion (Cold Lap is another term for this defect) -poor procedure control results in excessive spatter, expensive clean up -welding outdoors may require windscreens to prevent loss of shielding gas to the wind

What reduces Spatter and improves weld bead appearance on carbon steel applications?

.75 / Argon + 25% CO2

Most wire drives will provide a range of how many inches per minute (IPM)?

70-800 IPM

What is Shielding Gas?

A factor of the method of metal transfer

Short Circuiting Metal Transfer (GMAW-S)

A mode of metal transfer whereby a continuously fed solid or metal cored wire electrode is deposited during repeated electrode short circuits. LOW HEAT INPUT/SMALLER DIAMETER ELECTRODES ARE USED (0.025 in.-0.045 in.)

What does Silicon do?

Additions of silicon increase tensile and yield strength/ also a deoxidizer to remove oxygen

Inductance

An inductor is often a coil of wire wrapped around a material called the core. When an electric current is passed through the coil, a magnetic field is formed.

What can be attached to the inside of the welding hood to magnify the weld pool and make seeing it much easier?

Auxiliary Magnification Lenses

What presented a problem for semi automatic welding?

Constant Current - It is difficult to maintain the same Contact Tip Work Distance (CTWD)

What can decrease fatigue?

Correct head and body positioning

ER70-X the X stands for

Deoxidizers (2,3,4,6,7,and G)- substance used to remove oxygen from a material

ER70S-X the E stands for

Electrode- current carrying device

GMAW (MIG) is depended on what?

Gas Metal Arc Welding/ Metal Inert Gas- Level of current (Amps) required by the welding application and capacity of the torch.

When is Constant Current used? hint CC= (SMAW), (GTAW)

In Shield Metal Arc Welding (SMAW) and Gas Tungsten Arc Welding (GTAW)

What is Inductance and why does it Increase Puddle Fluidity?

Inductance controls how fast the current rises to reach the amps that have been selected when short circuit welding.

What does a constant voltage provide?

It provides a specific ARC Voltage for preselected wire feed speeds.

What does Copper do? - a carbon (critical element found in GMAW Solid Wire Electrodes

It's a coating, and it increases conductivity and arc starts

What is Amperage?

It's controlled by wire feed speed. The higher the amperage the more heat is applied to the weld.

In semi automatic GMAW, the operator sets the welding parameters, and the welding gun is controlled by a mechanical device.

Operator Appeal because reduces the heat transferred to the GMAW torch handle

This combines chemically with the weld pool to produce a desirable effect.

Reactive Gas

Phosphorous

Restricted by AWS, Too much can lead to Weld Cracking

Sulfur

Restricted by AWS, limited amounts can improve fluidity and wetting, but can also contribute to weld cracking

ER70S-X the R stands for

Rod

Wire feed speed (WPS) function?

Sets the speed that electrode will be fed from the wire drive through the welding gun and out the contact tip.

ER70S-X the S stands for

Solid Electrode Wire

What is the correct head and body positioning?

Stance includes good posture, feet at shoulder width, even weight distribution and a preparation to weld.

Three part blends of this are common for stainless steel for reducing splatter.

Ternary Gas Shielding Blends

Most lens shade recommendations are based on what?

The amperage ranges being used with the welding process

What is Current Density?

The larger the electrode the more amperage it can carry.

ER70S-X the 70 stands for

The minimum as welded tensile strength measure in thousands of pounds per square inch (ksi)

GMAW variables - Increasing electrode extension increases what?

The resistance to the flow of current in the electrode, thus the current in the arc is decreased.

The travel angle of the welding torch or electrode tilted in the direction of travel should be at what angle?

The welding torch or electrode tilted in the direction of travel is less than 90% between the electrode axis and a line perpendicular to the weld axis.

What happens with the Contact Tip Work Distance (CTWD) decreases?

There is an increase in the welding current.

This is an inert gas and will not react chemically with the weld pool.

Types of Shielding Gas

What is Constant Current?

Welding using a voltage that varies slightly with changes in current.

What is Constant Voltage? hint CV = (GMAW), (FCAW)

Welding using a voltage that varies slightly with changes in current. Often used for Gas Metal Arc Welding (GMAW) and Flux-Cored Arc Welding (FCAW).

Is the smaller the diameter of aluminum electrode wire more difficult to feed?

Yes, small wire more difficult to feed - (0,030 inches) and (0.047 inches)

Why are sight lines important?

You must be able to see the weld pool to control it. The sight lines can change with the position of the weld coupon. Poor sight lines cause eye fatigue and headaches.

What determines body positioning?

Your dominant hand (right vs left)