Forming & Layout #8
The flat layout or blank length of a piece of metal from which a simple L-shaped bracket 3 inches by 1 inch is to be bent depends upon the radius of the desired bend. The bracket which will require the greatest amount of material is one which has a bend radius of
1/8"
A piece of flat stock that is to be bent to a closed angle of 15° must be bent through an angle of
165 degrees
The purpose of a joggle is to
allow clearance for a sheet or an extrusion.
A piece of sheet metal is bent to a certain radius. The curvature of the bend is referred to as the
bend radius
If it is necessary to compute a bend allowance problem and bend allowance tables are not available, the neutral axis of the bend can be
found by adding approximately 1/2 of the stock thickness to the bend radius
Unless otherwise specified, the radius of a bend is the
inside radius of the metal being formed
The sharpest bend that can be placed in a piece of metal without critically weakening the part is called the
minimum radius of bend
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
neutral line
The sight line on a sheet metal flat layout to be bent in a cornice or box brake is measured and marked
one radius from the bend tangent line that is placed under the brake
The most important factors needed to make a flat pattern layout are
radius, thickness and degree of bend
If a streamline cover plate is to be hand formed using a form block, a piece of dead soft aluminum should first be placed over the hollow portion of the mold and securely fastened in place. The bumping operation should be
started by tapping the aluminum lightly around the edges and gradually working down into the center
On a sheet metal fitting layout with a single bend, allow for stretching by
subtracting the setback from both legs
When a piece of aluminum alloy is to be bent using a minimum radius for the type and thickness of material,
the layout should be made so that the bend will be 90 degrees to the grain of the sheet
