This document discusses various sheet metal processes and forming operations. It describes common sheet metal materials and characteristics. Various presses and cutting dies are discussed for operations like blanking, piercing, and bending. Specific forming processes like drawing, stretching, spinning, hydroforming and magnetic pulse forming are explained. Tests for assessing formability of sheet metals are also summarized.

1. SHEET METAL PROCESSES
UNIT-4

2. Introduction
 The working of metal thickness from 3mm to 5mm
with hand tools and simple machines into various
forms is known as sheet metal work.
Sheet metals
 Black iron
 Galvanized iron
 Stainless steel
 Brass
 Copper
 Zinc , Aluminium, tin plate and lead.

3. SHEET METAL CHARACTERISTICS
-Roll Forming
-Stretch Forming
-Drawing
-Stamping
-Rubber Forming
-Spinning
-Super Plastic Forming
-Peen Forming
-Explosive Forming
-Magnetic Pulse Forming

4. PRESSES

5. Mechanically Operated Power Press
or OBI Press

6. Inclined Press

7. Inclinable Presss

8. Types of Cutting Dies
1.Progressive Dies

9. Compound Dies

10. Blanking

11. Piercing

12. CUTTING OPERATIONS

13. PHASES IN SHEARING

14. SHEARING OPERATION - BENDING
TYPES OF BENDING OPERATION
- Angle Bending

15. - Angle Bending
- Roll Bending

16. - Roll Forming
If the edges are formed to a desired shape in the form of bend is
made on the sheet metal
- Seaming
The process of providing lock between the two edges of the
different work metal.
SHEARING OPERATION - DRAWING
- Deep Drawing
Length of the part drawn is deeper then width.
- Box Drawing
Length of the part drawn is lesser then width

17. STRETCH FORMING OPERATION
Stretching is the process of stressing the work blank beyond its elastic limit
by moving a form block towards the blank.
FORM BLOCK METHOD

18. FORM BLOCK METHOD
MATING DIE METHOD

19. SPECIAL FORMING PROCESSES
1.0 HYDRO FORMING
1.Hydro Forming
2. Rubber Pad Forming
3. Metal Spinning
4. Explosive forming
5.Magnetic pulse forming
6. Peen forming
7. Super plastic forming
a) Hydro Mechanical forming
b) Electro Hydraulic Forming

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21. 1) Hydro mechanical Forming

22. b) Electro Hydraulic Forming

23. 2.0 RUBBER PAD FORMING

24. RUBBER HYDROFORMING PROCESS

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26. 3.0 METAL SPINNING
a) Manual Spinning
b) Power Spinning
Applications: Ash trays, flower pots, lamp shades, missile and radar units

27. 4).EXPLOSIVE FORMING PROCESSES
- Stand off operations
The explosive charge is located at some distance away from the blank
and energy is transmitted through some fluid medium such as water.
- Contact Operations
The explosive charge is directly located over the blank.
AEROSPACE COMPONENTS

28. Electro magnetic forming
 The energy stored in a capacitor bank is discharged
rapidly through a magnetic coil.
 EX: a ring shaped coil is placed over a tubular
workpiece.
 Depends upon the shape of the die the tube will
deform when the magnetic force pushes the metal.
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29. 5.0 MAGNETIC PULSE FORMING PROCESS

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32. 6.0 PEEN FORMING PROCESS

33. 7.0 SUPER PLASTIC FORMING PROCESS
a) Loading
b) Forming
c) Forming
d) Release

34. Advantage:
 One step process
 Minimizes amount of scrap
 Higher material elongation possible
Application:
 Forming of– automotive body panels, aircraft frames

35. BASIC SHEARING OPERATION
1.0 Cutting operations
(a) Blanking

36. BASIC SHEARING OPERATION
1.0 Cutting operations

37. BASIC SHEARING OPERATION
1.0 Cutting operations

38. BASIC SHEARING OPERATION
2.0 Forming operations
(a) Bending
(b) Drawing
(c) Sequeezing
(d) Embossing
(e) Nibbling
It is an operation of cutting any shape from sheet metal
without special tools. It is done on a nibbling machine.

39. FORMABILITY OF SHEETMETAL
Formability = f(f1, f2)
F1 = Material Variables - ductility
F2 = Process Variables – stress system, lubrication, die design etc
Law 1 – Process of fracturing
Ductility of the same material is lower if the section size is large.
Law 2 –Law of geometrical Similitude
1 Blank are geometrically similar to dimension, thickness, width etc.
2 Unit strain at corresponding locations are identical
3 Forces required directly proportional to the square of the thickness
.
4 Consumption of work proportional to the cube of its thickness.

40. FORMABILITY TEST METHOD
1 Formability tests for bulk deformation
Elastic deformation and Plastic deformation
2 Formability test for elastic plastic deformation
1) Tensile test
a) Stretch forming - local thinning
b) Drawing operation – Lower punch by thinning under bi-axial stresses.
2) Simulative tests
a)Erichsen test – Stretchability based on erichsen number
b)Olsen test
c) Swift test - based on blank to punch diameter- drawing ratio
d) Fukui test – both assessed - based on formability index

41. FORMABILITY TEST METHOD
3) Full scale forming test