1. Sheet metal processing
Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Powder- and Ceramics Processing
Plastics processing
Cutting
Joining
Surface treatment

2. Sheet Metal Processes
Raw material: sheets of metal, rectangular, large
Raw material Processing: Rolling (anisotropic properties)
Processes:
Shearing
Punching
Bending
Deep drawing
Hydroforming

3. Shearing
A large scissors action, cutting the sheet along a straight line
Main use: to cut large sheet into smaller sizes for making parts.

4. Shearing
Shearing is a process for cutting sheet metal to size out of a larger stock such as roll stock. Shears are used as the preliminary step in preparing stock for stamping processes.
Material thickness ranges from mm to 6.35 mm (0.005 to in). The dimensional tolerance ranges from ±0.125 mm to ±1.5 mm (±0.005 to ±0.060 in).
The shearing process produces a shear edge burr, which can be minimized to less than 10% of the material thickness. The burr is a function of clearance between the punch and the die (which is nominally designed to be the material thickness), and the sharpness of the punch and the die.

5. Blanking / Punching
Blanking and punching are similar sheet metal cutting operations that involve cutting the sheet metal along a closed outline.
If the part that is cut out is the desired product, the operation is called blanking
and the product is called blank. If the remaining stock is the desired part, the operation is called punching.

6. Blanking / Punching

7. Cutting tool is a round/rectangular punch,
that goes through a hole, or die of same shape

8. Main uses: cutting holes in sheets; cutting sheet to required shape
Punching
Main uses: cutting holes in sheets; cutting sheet to required shape
nesting of parts
typical punched part
Exercise: how to determine optimal nesting?

9. Body of Olympus E-300 camera
Bending
Body of Olympus E-300 camera
component with multiple bending operations
component with punching,
bending, drawing operations
[image source: dpreview.com]

16. Typical bending operations and shapes

17. Sheet metal bending
Planning problem: what is the sequence in which we do the bending operations?
Avoid: part-tool, part-part, part-machine interference

18. Bending mechanics
Bending Planning  what is the length of blank we must use?
Ideal case: k = 0.5
Real cases: k = 0.33 ( R < 2T) ~~ k = 0.5 (R > 2T)

19. Bending: cracking, anisotropic effects, Poisson effect
Bending  plastic deformation
Engineering strain in bending = e = 1/( 1 + 2R/T)
Bending  disallow failure (cracking)  limits on corner radius: bend radius ≥ 3T
effect of anisotropic stock
Poisson effect
Exercise: how does anisotropic behavior affect planning?

21. (a) Compensation: the metal is bent by a larger angle
Bending: springback
Initial
Final R i f af ai T
How to handle springback:
(a) Compensation: the metal is bent by a larger angle
(b) Coining the bend:
at end of bend cycle, tool exerts large force, dwells
coining: press down hard, wait, release

22. Tooling: similar to punching operation,
Deep Drawing
Tooling: similar to punching operation,
Mechanics: similar to bending operation
Common applications: cooking pots, containers, …

24. Body of Olympus E-300 camera
Sheet metal parts with combination of operations
Body of Olympus E-300 camera
component with multiple bending operations
component with punching,
bending, drawing operations
[image source: dpreview.com]