sheet metal quiz

What is a sight line?

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

What is the bend tangent line?

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

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

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

The sight line on a sheet metal flat layout to be bent in a cornice or box brake is measured and marked one-half radius from either bend tangent line. one radius from either bend tangent line One radius from the bend tangent line that is placed under the brake.

One radius from the bend tangent line that is placed under the brake.

What is meant by set back?

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

A piece of sheet metal is bent to a certain radius. The curvature of the bend is referred to as the Bend allowance Neutral line Bend radius

bend radius

What factors must be considered in order to determine setback?

thickness of metal and the bend radius

The sharpest bend that can be placed in a piece of metal without critically weakening the part is called the Bend allowance Minimum radius of bend Maximum radius of bend

Minimum radius of bend

What is meant by bend allowance?

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

When a piece of aluminum alloy is to be bent using a minimum radius for the type and thickness of material, The piece should be bent slowly to eliminate cracking The layout should be made so that the bend will be 90° to the grain of the sheet. Less pressure than usual should be applied with the movable (upper) clamping bar.

The layout should be made so that the bend will be 90° to the grain of the sheet.

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

across the grain

What are the two special calculations that must be made when bending sheet metal?

bend allowance setback

Unless otherwise specified, the radius of a bend is the Inside radius of the metal being formed. Inside radius plus one-half the thickness of the metal being formed. Radius of the neutral axis plus one-half the thickness of the metal being formed.

inside radius of the metal being formed.

When bending metal, the material on the outside of the curve stretches while the material on the inside of the curve compresses. That part of the material which is not affected by either stress is the Mold line Bend tangent line Neutral line

neutral line

The most important factors needed to make a flat pattern layout are radius, thickness, and mold line . radius, thickness, and degree of bend the lengths of the legs (flat sections)

radius, thickness, and degree of bend

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

the alloy, metal thickness, and its hardness