Welding Flashcards
is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion.
Welding
——– is a primary concern to a welder. Metal oxides are formed in the welding zone of most metallic alloys when sufficient heat is applied.
Oxidation
is the blending of compatible molten metals into one common part or joint.
-Fusing of metals is accomplished by producing sufficient heat for the metals to melt, flow together and mix.
-The heat is then removed to allow the fused joint to solidify.
Fusion Welding
The two most prominent methods of welding air-craft structures and components are —– and —-
Fusion and non-fusion
The three principal methods of fusion welding are —–?
Gas, Electric arc, Electrical Resistance
-has, for some time, been the method of choice for constructing the structural framework of aircraft.
-results in superior strength joints because the metal parts are melted together into a single solid object.
Fusion Welding
Electric arc welding includes???
SMAW, GMAW, GTAW.
is the joining of metals by adhesion of one metal to another.
-The most prominent non-fusion welding processes used on aircraft are brazing and soldering, which are covered in detail later in this section.
Non-Fusion Welding.
two copper electrodes are held in the jaws of a vise-like machine and the pieces of metal to be welded are clamped between them.
Spot welding
-often referred to as gas welding, gets its name from the two gases, oxygen and acetylene, that are used to produce a flame.
- Acetylene is the fuel for the flame and oxygen sup-ports combustion and makes the flame hotter.
Oxyacetylene welding
produces a blinding light, with infrared and ultraviolet rays, which can burn both skin and eyes.
Electric arc welding
is the most common type of arc welding.
SMAW, or Shielded metal arc welding
The result of a weld is a?
JOINT
This equipment is commonly used to manufacture fuel tanks and other components where a continuous weld is needed.
Seam welding
Type of weld Joints
Butt joints
Tee joints
Lap Joints
Corner Joints
Edge Joints
are used to join metal forms such as sheet, bar, plate, tube and pipe.
Butt joints
results when two pieces of metal are brought together so that their edges form a —– of a box or rectangle.
This joint can only be used where load stresses are not significant.
Corner Joints
is the form of elec-tric arc welding that is used most in aircraft mainte-nance.
It also is known as gas tungsten arc welding (GTAW) and by the trade names of Heliarc and Heliweld .
TIG, or tungsten inert gas welding
formerly called Metal Inert Gas (MIG) welding, is used primarily in large volume production work.
GMAW, or gas metal arc welding
2 Types of electric Resistance welding
Spot welding
Seam Welding
are quite common in aircraft work, particularly in tubular structures.
Tee joints
Where load stresses are not significant, —– joints may be used to join two pieces of sheet metal.
Edge joints
is the exposed surface of the weld.
Face
is seldom used in aircraft structures when welding with gas, but is commonly used when spot welding.
Lap joints
is the metal that is deposited as the weld is made.
Bead
ontrolling the expansion and contraction of metals during welding is necessary to reduce distortion, warping and residual stress.
These effects are more noticeable when welding long sections of thin sheet metal.
Expansion and contraction of metal
Parts of the weld
Bead
Face
Root
Throat
Toe
Reinforcement
is the depth that fusion penetrates into the base metal.
Root
is the distance through the center from the root to the face.
Throat
Is the edge formed where the face of the weld meets the base metal.
Toe
is the quantity of weld metal added above the surface of the base metal.
Reinforcement
A weld must be formed correctly to achieve the intended strength and to resist joint fatigue.
If a joint is not made properly, the strength can be reduced as much as 50 percent.
Formation of the weld
2 principles of non fusion welding
Brazing and soldering
2 methods of tig welding
Straight polarity reverse polarity
