Sheet Metal Structures Flashcards
What it the grip length of a rivet?
Grip length is the combined thickness of all materials to be joined by the rivet.
Where are special rivets, such as Huck or Cherry-Lok, used?
Used in places where access to both sides of the structure is impossible or where limited space will not permit use of a bucking bar. Often called blind rivets.
What is bonded honeycomb (sandwich) construction?
Laminar construction using a combination of dissimilar materials, assembled and fixed in relation to each other. Properties of each material attains specific structural advantages for assembly as a whole.
What type of materials are used on honeycomb construction?
Stainless steel, Titanium, Magnesium metals. Plywood. Resin-impregnated paper, E-glass, Nylon, or cotton cloth.
Where are sandwich construction assemblies used?
Bulkheads, control surfaces, fuselage panels, wing panels, radomes, empennage skins, or shear webs.
What procedures should be used to prevent damage to the hole when drilling Plexiglas?
Backed with wood, feed slowed as drill breaks through underside. Drill bit is modified to a 60 degree tip angle, cutting edge to a zero rake angle, and back lip clearance angle increased to 12-15 degrees.
What calculation must be made when bending sheet metal?
Need: (1) degree of the bend, (2) radius of the bend, (3) thickness of the metal, and (4) type of metal used. This information is needed to determine the linear length of material needed for the bend to insure the final dimensions will be correct. Formulas and charts are available using the factors given.
What factors are used to determine setback?
The radius of the bend and the thickness of the material. Setback = radius + thickness.
What is a joggle?
A joggle is an offset near the edge of a piece of sheet metal to allow clearance for a sheet or an extrusion.
What are several methods used in forming sheet metal?
Folding, bumping, crimping, shrinking and stretching.
What is crazing and how does it occur?
Crazing is the formation of hairline fractures in the surface of plastic. Crazing occurs due to uneven expansion of the material causing excessive stress. May also be caused by harmful solvents.
Briefly describe the anodizing process and the purpose it serves.
Place an aluminum alloy in an electronic bath to grow a thin film of aluminum hydroxide on its surface. The purpose of this film is to provide resistance to corrosion and an excellent bond for paint.
What is the proper dimensions for the proper shop head of a rivet?
1 and 1/2 times the diameter of the shank in width and 1/2 times the diameter in height after bucking.
When inspecting Plexiglas, what should you look for?
Crazing and discoloration.
What causes honeycomb structure to delaminate?
Moisture.
