24ME303 MANUFACTURING PROCESS UNIT - IV.ppt

24ME303 MANUFACTURING PROCESS UNIT -IV PROCESSING OF SHEET METAL AND PLASTICS

1. PROCESSING OF SHEET METAL AND PLASTICS
Sheet metal characteristics Typical Shearing, Bending and Drawing
operations Stretch forming operations -Principle and application of special
forming processes: Hydro forming - Rubber pad forming - Metal spinning -
Explosive forming - Magnetic pulse forming - Peen forming Super plastic
forming. Plastics- Types and characteristics- Principles and typical
applications of: injection moulding - Plunger and screw machines -
Compression moulding. Transfer Moulding.

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. Classification of sheet metal
operation
Shearing
1. punching
2. blanking
3. perforating
4. parting
5. notching
6.lancing
Forming-bending, stretching, drawing, roll forming
Finishing process.

5. PRESSES

6. Properties of sheet metal:
Strength- tensile strength, shear strength,
compressive strength
Elongation
Elasticity
Modulus of elasticity
Ductility
Plasticity
Hardness
Corrosive resistance.

7. Mechanically Operated Power Press
or OBI Press

8. Inclined Press

9. Inclinable Presss

10. Types of Cutting Dies
1.Progressive Dies

11. Compound Dies

12. Blanking

13. Piercing

14. CUTTING OPERATIONS

15. Blanking
Blanking is the operation of cutting a flat shape
from the sheet metal
Piercing or punching:
* It is the operation of producing the hole on the
work piece by a punch

16. PHASES IN SHEARING

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

19. - Angle Bending
- Roll Bending

20. - 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

21. 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

22. FORM BLOCK METHOD
MATING DIE METHOD

23. 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

24. YoucaN

25. 1) Hydro mechanical Forming

26. b) Electro Hydraulic Forming

27. 2.0 RUBBER PAD FORMING

28. RUBBER HYDROFORMING PROCESS

29. YoucaN

30. 3.0 METAL SPINNING
a) Manual Spinning
b) Power Spinning
Applications: Ash trays, flower pots, lamp shades, missile and radar units

31. 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

32. 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.
YoucaN

33. 5.0 MAGNETIC PULSE FORMING PROCESS

34. YoucaN

35. 6.0 PEEN FORMING PROCESS

36. In this process, a stream of balls or metals shots
is blasted against the surface of the sheet metal
blank to be made into the required shape.
The part to be made by the sheet metal placed on
a form block or it may be suspended from
support.

37. 7.0 SUPER PLASTIC FORMING PROCESS
a) Loading
b) Forming
c) Forming
d) Release

38. This method involves in hot forming upto 1000 c
superplastic alloys using an inert gas pressure
upto 50bar.
Advantage:
One step process
Minimizes amount of scrap
Higher material elongation possible
Application:
Forming of– automotive body panels, aircraft
frames

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

40. BASIC SHEARING OPERATION
1.0 Cutting operations

41. BASIC SHEARING OPERATION
1.0 Cutting operations

42. 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.

43. ORGANIC MATERIALS
Natural – Wood, Coal, Petroleum &
Natural Rubber
Synthetic – Plastics, Synthetic rubber,
Ceramics & Glass
Organic material - Polymers

44. Polymers
Poly means ‘Many’ & ‘Mers’ means ‘Parts’
Polymer built of several repeating
units(Monomer)
Monomer – small molecules
Polymer is made up of thousands of
monomers jointed together to form large
molecule.
Plastics – Organic polymer

45. Polymerization process
A Polymer is made up of linking thousands
of monomer and thus obtaining large
molecule is called Polymerization process
Additives – Plasticizers (liquid form) –
Water, Organic solvents & resins
Catalyst – Promote faster & complete
Polymerization
Dyes – Impart desired colour
Initiators – Initiate the reaction (H
2O
2)
Hydrogen peroxide

46. Plastics
Can be moulded into required shape
with the help of pressure or heat or
both heat and pressure
Resin – liquid form of plastics, also raw
material for making plastics
Types of resin: acrylic resin,
Polyethylene resin & amino resin –
Produced by polymerization process
Catalysts, Binders & Lubricants added
with resin to form plastics

47. Modifiers – To improve the mechanical
properties of plastics
Lubricants – To reduce friction during
processing , Avoid sticking to mould walls(Oils,
Soaps and waxes)
Solvents – Dissolve fillers or Plasticizers & Allow
the processing in fluid state(Alcohol)
Fillers – Mica, Cloth fiber
Elastomers – To enhance the elastic properties

48. Properties of Plastics
Elongation
Heat resistance
High rigidity
Surface hardness
High viscosity
Density
Chemical resistance

49. Thermosetting Plastics
Thermosetting - Plastics which are hardened
by heat effecting non reversible chemical
change . Molecules are formed by
condensation polymerization process.
All the molecules have three dimensional
network and very strong binding force
between molecules
Bakelite, Polyester resin, Epoxy
resin(Araldite), Silicones, Urea
formaldehyde(Amino resin) & Alkyds

50. Thermo Plastics
Have separate long and large size molecule arranged
side by side
When thermoplastics are heated it becomes very soft
and rehardens on cooling
During heating the linear bonding links between
molecules are breakup and separated. Relinking takes
place on cooling and retains their hardness.
Cellulose nitrate – pen bodies, Table tennis balls, Frames
Ethyl cellulose – Jigs, Fixtures, hose nozzles
Cellulose acetate - Radio cabinets, steering wheels,
Insulating tapes

51. Synthetic resins
Polyethylene – Fabrics, tray, pipes, tubing chemical
containers & corrosion resistant coatings
 Polystyrene - Battery boxes, radio parts, toys
Vinyles(PVC) – Tarpaulin, Water roofing, raincoats, tubes
Polytetra fluroethylene (Teflon)- Gaskets, Greaseless
bearing, Electrical insulators, Chemical containers
Polyamide(Nylon) – Gears, wire insulation, combs,
Bearings and couplings

52. S.
No
Thermoplastics Thermosetting
plastics
1 Softened by heating Cannot be softened by
heating
2 Structure is made of
linear chain molecule
Structure is made of
cross-linked molecule
3 Produced by addition
polymerization process
Produced by condensation
polymerization process
4 Can be reproduced by
heating and cooling
Cannot be reproduced
5When the temp increases
the plasticity also
increases
Plasticity is stable at high
temperature
6 Softer and less strong Harder and strong
7 Scrap can be reused Scrap can not be reused

53. INJECTION MOULDING
1) RAM OR PLUNGER TYPE INJECTION MOULDING

54. THERMOPLASTICS - INJECTION MOULDING
2) SCREW TYPE INJECTION MOULDING

55. THERMOPLASTICS – INDUSTRIAL APPLICATION
2) BLOW MOULDING

56. THERMOPLASTICS – INDUSTRIAL APPLICATION
3) ROTATIONAL MOULDING

57. THERMOPLASTICS – INDUSTRIAL APPLICATION
4) FILM BLOWING

58. THERMOPLASTICS – INDUSTRIAL APPLICATION
5)SHEET MAKING
*Calendering process is used for sheet making.
*A calender is a series of hard pressure rollers used to form
or smooth a sheet of material such as paper or plastic film.
*thickness of the sheet is controlled by combination of
squeezing and altering the speed of rolls.

59. THERMOPLASTICS – INDUSTRIAL APPLICATION
6) EXTRUSION PROCESS

60. THERMOPLASTICS – INDUSTRIAL APPLICATION
7) VACUUM FORMING PROCESS ( THERMO FORMING)

63. THERMOSETS
1) COMPRESSION MOULDING

64. THERMOSETS
2) TRANSFER MOULDING

65. BONDING OF THERMOPLASTICS
Laminations:
•It is done by the applications of heat and pressure. It
consist of layers such as paper, cellulose, glass fiber
etc.
• thermoplastics are bonded by the process of
lamination.
• the pressure applied is 7MPa and temperature
about 150 C

66. The methods of joining plastics
and composites:
Mechanical fastening
Uses of additional parts such as metallic screws,
bolts, washers, rivets.
Adhesive and solvent bonding
Adhesive is placed between parts to be bonded
where it serves as the material that joins the
parts and transmits the load through the joint.
Welding or fusion bonding.

67. YoucaN

68. Friction bonding or friction
welding
Friction welding of PVC tubes and pipes is well
developed. Prior to welding process, the ends of
the tubes are sized by heating the tube ends oil to
100 C for 3 to 4 minutes and then tube are
clamped in gauge for 3 minutes followed by
water cooling to room temperature.

69. Ultrasonic welding
Process in which mechanical vibrations of high
frequency are used. The frequency range from
15 to 20 kHz.
Transducer which converts high frequency
energy supplied by ultrasonic oscillator into
vibrations.
It is possible to weld acetyl, nylon nd high
density polyethylene, PVC