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.