Welding Test. Airframe

FAA Airframe welding study guide.

What is the definition of welding?

The process that joins metal by melting or hammering the work pieces until they are joined together

What are the general types of welding?

Gas, electric arc, gas metal arc, tungsten arc, plasma arc, shielded metal arc, friction welding, electric resistance, spot and seam welding

Describe gas welding

heating ends or edges of metal parts to a molten state with a high temp flame

list the equipment used in gas welding

acetylene and oxygen tank

regulators and cylinder pressure gauge

red hose for acetylene, green for oxygen

welding torch with tips, connections

PPE

flint spark

tank valve wrench

fire extinguisher

describe the temperatures used in gas welding

oxy acetylene - 6300F

hydrogen - 4800F

describe shielded metal arc welding (SMAW)

Consists of a rod covered in welding flux that is connected by a heavy electric wire. Arc is struck between the rod and material to create heat for welding. Most common type of welding, also known as stick welding.

describe the action of the flux in stick welding

when it melts, the inert gas is released to shield the molten puddle from oxidization

describe gas metal arc welding (GMAW)

Uncoated wire electrode is fed into and through the torch. An inert gas such as argon or CO2 flows around the wire to shield the puddle from oxygen and contaminants, allowing for a clean weld. MIG welding.

what is GMAW welding used for in aviation, and not used for

used for welding large surface areas, and not high stress areas

describe gas tungsten arc welding (GTAW)

a welding process that uses a non-consumable tungsten electrode to produce the weld. a filler rod is manually fed. An inert gas, typically argon, is used to protect the weld area from contamination, allowing for precise and clean welds. TIG welding

describe plasma arc welding

a welding process that uses a plasma jet generated by ionizing gas to create a concentrated heat source. It is capable of welding various materials and is known for its precision and ability to weld thin sections. Bore copper nozzle

describe spot welding

a process that joins two or more metal sheets by applying heat and pressure to specific points, creating localized welds.

describe acetylene and its use in welding

a primary fuel, stored in containers. used for welding and cutting. Chemically unstable. Never set the pressure gauge higher than 15 psi.

describe argon and its use in welding

No color, taste or odor. Non-toxic and used as a gas shield for mig + tig welds and plasma welds.

describe helium and its use for welding

Colorless, odorless, tasteless, non toxic inert gas. Used as a gas shield for the electrode. Lowest boiling and melting points of all elements

describe hydrogen and its use in welding

colorless, odorless, tasteless, highly flammable. Used at a higher pressure than acetylene, used for underwater welding and cutting

describe oxygen and its use in welding

colorless, odorless, tasteless, and is used in the welding process to increase combustion rate (increase flame temp)

describe an equal pressure torch

Most common used torch for oxy-acetylene welds. Mixing chamber for acetylene fuel at 1-15 PSI. Flames are easy to adjust.

describe torch tips and sizes

Tips deliver and control the final flow of gases. Tip sizes are designated by numbers

describe a backfire

A momentary backward flow of the gases at the torch tip

describe torch lighters

Consists of a piece of steel, and replaceable flint. when drawn across the steel, the flint shoots sparks to light up the torch

describe storage and transport of gas cylinders

Should be stored and transported upright, chained up, because of an absorbent material saturated with liquid acetone. Keep steel cap on till put into service.

describe the setup and connection of a regulator

Attached to a gas cylinder and used to lower the cylinder pressure to desired working pressure

describe the process of connection of the hoses

acetylene hose is red, left hand thread

oxygen hose is green, right hand thread

describe the leak check prior to lighting a torch

spray soapy water on all hoses and connections

describe a neutral flame

Balance flame where the amount of oxygen and fuel gas are perfectly mixed. Results in flame with no excess of either gas.

describe a carburizing flame

A flame that has too much fuel gas and not enough oxygen. It produces a soft yellow flame with excess carbon.

describe an oxidizing flame

Produced by excess oxygen, shorter outer flame, small bluish white inner core (6300F)

describe a flashback

When the tip is overheated and the gas burns before making it out of the tip. Caused by loose connections, improper pressures or overheating the torch.

describe the molten puddle formed when gas welding

It is formed along the path in which the flame is desired

describe the characteristics of a good weld

Smooth seam, even bead, uniform thickness, taper off smoothly into base metal, no oxidization, blowholes, porosity, burns, cracks

describe brazing

An action of forming or fixing sheets of metal with soldering with an alloy of copper and zinc

describe soldering

Thermally joining metal parts with a molten nonferrous alloy that melts below 800F

what are the different joints used in gas metal welding

Butt joint, lap joint, T joint, corner joint, edge joint

How should torch be held in reference to the workpiece when gas welding?

In the most comfortable position that allows the tip to be in line with the joint to be welded. Inclined 30-60 degrees from perpendicular.