Airframe - AM.II.A.K4 - Layout, forming, and drilling of sheet metal components

Question 1

For maximum strength of a formed sheet metal fitting, should the bend be made along or across the grain of the metal?

Answer 1

Across the grain

Question 2

What determines the minimum bend radius that can be used when forming a sheet metal structural fitting? (3)

Answer 2

• The alloy
• The metal thickness
• and its hardness

Question 3

What is meant by the neutral axis in a sheet of metal?

Answer 3

The plane within the metal that neither stretches nor shrinks when the metal is being bent

Question 4

What is a mold line in the development of a flat pattern for a formed metal part?

Answer 4

An extension of the flat sides beyond the radius

Question 5

What is the bend tangent line?

Answer 5

A line in a flat pattern layout at which the bend starts

Question 6

What is meant by setback?

Answer 6

The distance the jaws of a brake must be set back from the mold line to form a bend

Question 7

What is meant by bend allowance?

Answer 7

• The actual amount of metal in a bend
• It is the distance between the bend tangent lines in a flat pattern layout

Question 8

What is a sight line?

Answer 8

• A line drawn on a flat pattern layout within the bend allowance that is one bent tangent line
• When the sight line is directly below the nose of the radius bar on the break, the bend will start at the bend tangent line

Question 9

What is the main function of throatless shears in an aircraft sheet metal shop? (3)

Answer 9

• cut mild carbon steel up to 10 gauge
• stainless steel up to 12 gauge
• irregular curves in the metal

Question 10

What kind of metal forming is done by a slip roll former?

Answer 10

Simple curves with large radii

Question 11

What kind of metal forming is done by bumping?

Answer 11

Compound curves in sheet metal

Question 12

When forming a curved angle, what must be done to the flanges?

Answer 12

The flanges must be stretched for a convex curve and shrunk for a concave curve

Question 13

When hand forming a piece of of sheet metal that has a concave curve, should the forming be started in the center of the curve, or at its edges?

Answer 13

Start at the edges and work toward the center

Question 14

What is meant by a joggle in a piece or sheet metal?

Answer 14

A joggle is a small offset near the edge of a piece of sheet metal that allow the sheet to overlap another piece of metal