GMAW, FCAW, GTAW, and Welding Safety: Comprehensive Course Notes

What is birdcaging in GMAW?

Birdcaging is when the wire bunches up between the drive rollers and the gun liner

Why is a respirator used in welding?

A respirator helps filter out hazardous fumes and gases produced during semi-automatic welding to protect the welder's respiratory system.

What is the primary function of gas in GMAW?

To shield the molten weld pool and arc from atmospheric contaminants like oxygen and nitrogen.

Why must drive rollers be changed in GMAW?

Drive rollers must be changed to accommodate different types of wire (solid

How can grinding tools contaminate stainless steel?

Grinding tools used on carbon steel can embed carbon steel particles into stainless steel

What is the safe distance from unshielded welding arcs?

Workers within 12 meters (40 ft) from unshielded welding arcs must wear appropriate eye protection.

What sensitivity does GMAW have?

GMAW is very sensitive to changes in voltage

Is mechanical ventilation effective for welding fumes?

True

What is the role of the gas diffuser in GMAW?

The gas diffuser ensures the shielding gas is delivered evenly around the welding wire and into the weld zone.

What is the safety distance for flammable materials during welding?

Flammable materials should be relocated at least 10m (33 ft) away from the welding area.

Is GMAW a semi-automatic process?

False

Is GMAW versatile?

True

What type of radiation do welding arcs produce?

Welding arcs primarily produce non-ionizing radiation

Why is GMAW considered efficient?

GMAW has a higher deposition rate due to its continuous electrode feed

What applications is GMAW less preferred for?

GMAW is less often the first choice for extremely heavy fabrication and thick plate applications like bridge building.

What toxic compound can form in welding fume from stainless steel?

Hexavalent chromium (Cr VI) can form due to the oxidation of chromium in stainless steel.

What can repeated exposure to UV radiation cause?

It can cause 'arc eye' (photokeratitis) and potentially lead to permanent damage to the cornea and retina.

What type of wire is used in GMAW?

The electrode in GMAW is a bare

What is 'arc eye'?

'Arc eye' is a sunburn of the cornea caused by intense exposure to UV radiation from the welding arc.

What is the hierarchy of control for welding fumes?

It prioritizes eliminating or reducing the hazard at the source

What increases deposition rates in FCAW?

A longer electrical stick-out increases the pre-heating of the wire

What does FCAW stand for?

FCAW stands for Flux Cored Arc Welding.

What percentage of Argon is needed for fine spray transfer in FCAW?

A minimum of 85% Argon is required.

What defect is caused by moisture in the electrode?

'Worm tracking' is characterized by longitudinal gas holes (porosity) on the weld surface.

What type of power source does FCAW use?

FCAW uses a Constant Voltage (CV) power source.

What roles does the flux core perform in FCAW?

The flux core stabilizes the arc

What polarity is FCAW-G typically operated with?

FCAW-G is almost always operated with Direct Current Electrode Positive (DC+).

What is the requirement for drive rollers in FCAW?

Knurled (serrated) drive rollers are required for flux-cored wires to ensure adequate traction.

What is the gas flow rate in FCAW-S?

FCAW-S is self-shielded

What is the function of the inch switch in a wire feeder?

The inch switch allows the operator to feed wire through the gun without striking an arc or turning on the gas.

What influences the mode of metal transfer in welding?

Shielding gases protect the weld and affect metal transfer from the wire to the weld pool.

Why does aluminum wire require specialized wire feeders?

Aluminum wire is very soft

What is the function of the purge switch in welding?

The purge switch activates the gas solenoid to set the flow rate without energizing the electrode or feeding the wire.

What does GMAW stand for?

GMAW stands for Gas Metal Arc Welding

What is a key requirement for GMAW?

GMAW requires careful adjustment of voltage and wire feed speed

What is the role of the gas diffuser in welding?

The gas diffuser ensures even

Why do different wire types require different drive rollers?

Different processes use different wire types

True or False: Wire feeders can be configured as push systems.

True

What is the welding gun's function?

The welding gun initiates the welding sequence

What type of drive rollers are used for soft wires like aluminum?

U-groove drive rollers are used to support soft wires without sharp pressure points.

What does a constant speed wire feeder maintain?

It maintains a consistent arc length regardless of minor changes in wire feed.

What travel angle is preferred in GMAW?

A slight forehand (push) travel angle of 5-10° is preferred.

What is birdcaging in welding?

Birdcaging is the kinking of wire that occurs before it enters the liner.

What must be correctly set to ensure reliable wire feed?

The drive roll pressure must be correctly set to avoid crushing or deforming the wire.

What is the contact tip in welding?

The contact tip transfers electrical current from the welding gun to the welding wire.

What happens when wire feed speed increases in a Constant Voltage system?

Increasing wire feed speed shortens the arc length

What type of drive rollers are standard for solid wires?

V-groove drive rollers are standard for solid wires like carbon and stainless steel.

What hazardous gas can be produced by the GTAW arc?

Ozone can be produced from the reaction of the arc with atmospheric oxygen.

What does a gas lens do in GTAW?

A gas lens smooths and laminarizes the flow of shielding gas.

Why is tungsten used in GTAW?

Tungsten has the highest melting point of all known metals

What is unique about GTAW regarding filler metal?

GTAW can be performed autogenously

What protects the torch components from the arc's heat in GTAW?

The ceramic gas cup protects the torch from intense heat.

What contaminants are particularly harmful to the GTAW weld pool?

Nitrogen and oxygen are harmful as they cause porosity and oxidation.

What does pulsed GTAW do to heat input?

Pulsed GTAW decreases overall heat input

What type of power source is used in GTAW to maintain stable current?

Constant Current (CC) power sources are used for stable current despite changes in arc length.

What deadly gas can be created from the arc's UV light?

Phosgene can be created when the arc reacts with chlorinated degreasing agents.

True or False: Self-shielded flux-cored electrodes rely on flux ingredients for shielding.

True

What are the three slag-free processes mentioned?

GMAW (MIG)

What are FCAW and SMAW processes known for?

Both produce a slag layer.

What effect does adding oxygen to Argon in shielding gas have?

It dramatically lowers the surface tension of the weld puddle

What is a major limitation of the FCAW process?

High volume of fume generation compared to solid-wire processes like GMAW.

What does the drooping characteristic curve of a CC power source indicate?

A small change in voltage results in only a minor change in current

What is true about MCAW wires?

They typically contain metal powders

What safety hazard can high frequency units used in GTAW cause?

They can generate electromagnetic interference that poses potential safety hazards to sensitive electronic equipment.

What type of power sources do GTAW and SMAW use?

Constant Current (CC) power sources.

Why does GTAW generally have the lowest deposition rate?

It often requires a slower travel speed and filler metal is typically added manually.

What type of machines are GTAW power sources?

Constant Current (CC) type machines.

What is the reactive gas used in welding that can freeze the regulator?

Carbon dioxide.

Is CO2 required for spray transfer?

False

What is the most expensive shielding gas?

Helium.

What does a low dew point indicate?

It indicates a very dry gas

What are Argon and Helium classified as?

Noble gases (Group 18 of the periodic table).

What does Argon shielding gas provide?

A more constricted

What is the most common gas mixture for general welding of carbon steel?

75% Argon

What is the purpose of 'cracking' a gas cylinder?

To purge any debris and dust inside the cylinder opening.

What does the 'S' in ER49S-6 stand for?

Solid wire

What does ER49S-6 classify as?

A Canadian Standards Association (CSA) classification for a solid carbon steel electrode.

What does the '6' in ER49S-6 indicate?

A high level of manganese and silicon

What are ER70S-6 and ER49S-6 commonly used for?

They are classifications for solid wires used in GMAW.

What is a common gas mix for short circuit/globular transfer?

75% Argon

What is the classification for a solid carbon steel electrode by AWS?

ER70S-6.

What is the primary benefit of hardfacing?

To improve wear resistance on a surface.

What is the purpose of hardfacing?

To provide a protective covering that resists wear.

Is pad welding suitable for decorative art pieces?

No

In which industries is hardfacing most commonly applied?

Mining

Are surfacing and pad welding more expensive than replacing worn equipment?

False

What is essential for proper fusion in welding?

Proper surface clean up and preparation

What is pad welding used for?

To build up and restore worn surfaces of machinery to their original dimensions.

What are the characteristics of hardfacing materials?

They have high abrasion resistance

What is necessary for a sound weld in hardfacing?

The removal of existing oxides and contaminants.

What pattern is used in hardfacing for maximum protection?

A lattice-like sequence or cross-hatching pattern.

What does the welding carriage provide in SAW?

Consistent movement and control of the welding torch.

What risk is increased if the arc is not fully covered by flux?

Increased risk of weld defects due to oxidation.

What is the role of granulated flux in SAW?

It completely submerges the arc to protect the weld and clean the metal.

What type of flux can be reused after sieving?

Only neutral fluxes that do not change the chemical composition of the weld metal.

What is a limitation of SAW?

It takes time to set up and has limited versatility in joint configuration.

What is a key feature of SAW that increases productivity?

A continuous wire feed enabling long

What must be done to the slag after cooling in SAW?

It must be carefully removed to expose the weld.

What generally has a negligible effect on the final weld shape?

Ambient temperature of the welding area.

In which industry is SAW less common?

The automotive industry