Sheet Metal Layout

Question 1

Element added for wrought aluminium:
2000
5000
6000
7000 series

Answer 1

2000 series: copper + Al (Alclad)
5000 series: magnesium + Al
6000 series: silicon + magnesium + Al
7000 series: zinc + Al

Question 2

factors to consider when bending aluminium sheets

Answer 2

1. Grain direction: bend across the grain (perpendicular)
2. Quality of cut edge: no burr on edges to be folded (edge polished)
3. Minimum bend radius: bend bigger than the permissible minimum bend radius

Question 3

What is minimum bend radius

Answer 3

smallest inside radius a sheet can be bent without cracking

Question 4

factors affecting minimum bend radius

Answer 4

material, thickness, temper condition (hardness)

Question 5

types of bending stresses

Answer 5

metal outside: stretched (tensile stress)
metal inside: squeezed (compressive stress)
neutral axis: zero stress (no change in length before or after)
failure: fracture on outside (tensile failure) and wrinkling (compression failure) on inside

Question 6

What is springback

Answer 6

springback occurs when the metal is stressed below the elastic limit

Question 7

what is setback

Answer 7

setback is the distance from the bend tangent line to the mold point

Question 8

setback formula

Answer 8

SB = (Ri +T) * K

Ri = inside radius of bend
T = Thickness
K = K chart value

Question 9

relief holes usage

Answer 9

allow metal to flow at the corner during bending

Question 10

tool colour used for cutting

1) straight, clockwise, anticlockwise
2) straight, anticlockwise
3) straight, clockwise

Answer 10

1) yellow
2) red
3) green

Question 11

most important factors needed to make a flat pattern layout are

Answer 11

radius, thickness, degree of bend

Question 12

what type of mallet is used to form sheet metal

Answer 12

copper mallet

Question 13

bend allowance formula

Answer 13

BA = A/360 * 2pi * (Ri + (c*T))

A = angle
Ri = internal radius
c = given
T = thickness