AGR 170- Welding

What is welding?

the joining together of materials, most often metals, using heat and/or pressure.

What mixture produces the hottest flame known to man (5700F)?

Acetylene/Oxygen Mixture

What welding processes are most commonly used on farms?

ARC Welding

Whose responsibility is safety?

Everyones

What is PPE (personal protective equipment)?

Any device used to prevent injury.

When should safety glasses be worn in the shop?

At all times

Welding produces ultra violet and infared rays that can burn what parts of your body?

Eyes and Skin

What PPE is needed by welders?

Eye protection, proper clothing, hearing protection

What is the minimum shade lens needed when using an ARC welder?

Shade #10

What PSI does acetylene become volatile at?

15 PSI

What should you do if a gas regulator malfunctions?

Discard regulator and replace with new one

When lighting a torch, what type of ignition source should you use?

ONLY an approved spark type striker

Define Backfire

When flame goes out with a loud pop

Define Flashback

when flame goes back into the mixing chamber and burns with a shrill hissing or squealing noise.

What should you yell before you strike and ARC with the striker?

Cover!

What are the four types of fire extinguishers?

A, B, C, D

Type A Extinguisher

Ordinary Combustibles: wood, paper, etc.

Type B Extinguisher

Flammable Liquid: paint, gasoline, etc.

Type C Extinguisher

Electric equipment: electric motor, circuit panel

Type D Extinguisher

Combustible metals: zirconium

Where should welding be performed?

In well ventilated areas

How far should the oxygen cylinder valve be opened?

All the way

How far should the acetylene cylinder valve be open?

1/4 to 1/2 turn

Which valve should be closed first when shutting off torch?

Acetylene valve

What psi are oxygen cylinders charged with?

2200 psi

How is acetylene kept stable in the cylinder?

Keeping pressure the same

What is the ratio of oxygen to acetylene gas that will produce a neutral flame?

one:one

When cutting metal with oxy-acetylene torch, what is the minimum shade number you should use to protect your eyes?

Shade #5

What are electrodes coated with?

flux

What is the purpose of flux?

-Acts as a cleansing and deoxidizing aggent in the molten crater

-Release carbon dioxide to form a gas shield

-Form slag over completed weld

-Provide easier arc starting, stabilize are better, and reduce splatter

-Permit penetration and improve quality of weld

Where should electrodes be stored?

In a dry place at room temperature

What are two methods of striking and ARC with a "stick" welder?

Tapping, scratching

GMAW is more commonly known as what?

MIG welding

What shielding gas is most commonly used for welding steel?

Argon

What three events occur when the trigger is pulled on a MIG welding gun?

Current flows, shielding gas flows, wire is fed through gun

Ampere

the amount of current that flows in a circuit

Volt/Voltage

force that causes current to flow (electrical pressure)

Undercutting

Groove is left in base metal on either side of the bead

Overlap

metal doesn't fuse with base metal. caused by too little current

What are the three things that can be adjusted on a MIG welder?

Gas flow rate, Wire speed, Voltage