Metallic structures Flashcards
(8 cards)
What is the main function of throatless shears in an aircraft sheet metal shop?
Throatless shears are used to cut mild carbon steel up to 10-gage, and stainless steel up to 12-gage. They can be used to cut irregular curves in the metal.
What kind of metal forming is done by bumping?
Compound curves in sheet metal.
What must be done to the flanges of an angle for it to be curved?
The flanges must be stretched for a convex curve and shrunk for a concave curve.
Why are the lightening holes in a sheet metal wing rib flanged?
Flanging the lightening holes gives the rib rigidity.
What is the purpose of anodizing a piece of aluminum alloy, and how is it applied?
Anodizing is a protective oxide film that is deposited on the surface of the aluminum alloy by an electrolytic process.
What is the difference in the appearance of an oxidizing flame, a neutral flame, and a reducing flame produced by an oxy-acetylene torch?
An oxidizing flame has a pointed inner cone, and the torch makes a hissing sound. A neutral flame has a rounded inner cone, and there is no feather around the inner cone. A reducing flame has a definite feather around the inner cone.
Why must thick plates of metal be preheated before they are welded?
Preheating is a method of controlling the expansion and contraction of the metal that is being welded. Preheating minimizes the stresses that are cause when welding thick metal.
What is meant by a soft flame?
a soft flame is one that is made when the pressures of the gases are low enough that the flame does not make a noise and does not blow the puddle.
