Metal Forming Process

1. DEPT & SEM : ME & III-II
SUBJECT NAME : METAL FORMING PROCESS
COURSE CODE : MFP
UNIT : I
PREPARED BY : Dr. N. RAJESH
COURSE: MFP UNIT: 1 Pg. 1

2. COURSE: MFP UNIT: 1 Pg. 2
Students can able to:
 Get knowledge on basic concept of hot and cold working process
 Cold Working Vs Hot Working
 Advantages, Dis Advantages & Applications of Cold and Hot working process
TOPIC OUTCOMES

3. COURSE: MFP UNIT: 1 Pg. 3
o Manufacturing Process is a very fundamental subject in Mechanical
Engineering
o There are various Manufacturing process by which a product can be made
o Each process however has its own limitations and restrictions and due to
this a particular process is more suited to its specific applications
 Classification according to temperature
 Cold Working
 Semi Hot working
 Hot Working
 Cold Working Vs Hot working
OUTLINE

4. COURSE: MFP UNIT: 1 Pg. 4
CLASSIFICATION ACC TO WORKING TEMPERATURE
1. Cold Forming
2. Hot Forming
3. Warm (OR)
Semi hot
forming
Fig.1.32 CLASSIFICATION OF METAL FORMING PROCESS

5. COURSE: MFP UNIT: 1 Pg. 5
COLD WORKING
 Cold working can be defined as plastic deforming of metals and alloys under
condition of temperature and strain rate such that the work hardening or strain
hardening is not relieved.
 The working temperature for cold working is below the re crystallization
temperature of the metal / alloy
 Cold working is carried out at room temperature or at temperature less than
0.3 X Tm i.e. melting point of the metal.

6. COURSE: MFP UNIT: 1 Pg. 6
CHARACTERSTICS OF COLD WORKING
 Due to work hardening the strength of metal increases but its ability to deform
further decreases
 So if the metal is excessively deformed, it may fracture before it is formed
 To avoid this, immediate annealing is done which will soften the material and
restore its ductility and hence the formability
Fig.1.33 EFFECTS OF COLD WORKING AND ANNEALING

7. COURSE: MFP UNIT: 1 Pg. 7
ADVANTAGES OF COLD WORKING
 No oxidation and scaling of work material so reduced material loss
 Surface defects are removed
 High dimensional accuracy
 Mass production and automation
 Thin gauge sheets can be produced

8. COURSE: MFP UNIT: 1 Pg. 8
DIS ADVANTEGES OF COLD WORKING
 Large forces are needed for deformation
 Limited ductility so large deformation of cold working needs annealing so
production cost is high
 Only ductile materials are cold worked
MATERIALS FOR COLD WORKING
 Tool material must have higher strength than work material
 Tool must have reasonable tool life
 Maximum possible deformation should be obtained in a single working operation

9. COURSE: MFP UNIT: 1 Pg. 9
TYPES OF COLD WORKING PROCESS
1. Drawing
a) Blank drawing
b) Wire drawing
c) Tube drawing
d) Embossing
2. Squeezing
a) Coining
b) Sizing
c) Swaging
d) Knurling
e) Extrusion
3. Bending
a) Plate bending
b) Roll forming
c) Angle bending
d) Seaming

10. COURSE: MFP UNIT: 1 Pg. 10
HOT WORKING
 Defined as the plastic deformation of metals and alloys under the condition of
temperature and strain rate such that the recovery and re crystallization takes
place simultaneously with the deformation
 It is carried above the recrystallization temperature of the material
 0.7 to 0.9 times the melting temperature and a fine refined grained recrystallized
structure is obtained.

11. COURSE: MFP UNIT: 1 Pg. 11
CHARACTERSTICS OF HOT WORKING
 Occurs at constant load / flow stress, that there is no work hardening of the
material
ADVANTAGES OF HOT WORKING
 Strength of metals at high temperatures are low so less tonnage equipment's are
adequate
 Very large workpieces can be deformed with equipment of reasonable size
 Grain size can be controlled to be minimum. This makes the metal tougher

12. COURSE: MFP UNIT: 1 Pg. 12
DIS ADVANTEGES OF HOT WORKING
 Heavy material loss due to oxidation and scaling
 Automation is difficult
 High energy cost to heat the metals to high temperature
 Thin parts cannot be produced

13. COURSE: MFP UNIT: 1 Pg. 13
1. Hot forging
a) Hammer forging
b) Drop forging
c) Upset forging
d) Press forging
e) Roll forging
2. Hot forging
3. Hot extrusion
4. Drawing
5. Swaging
6. Hot spinning
TYPES OF HOT WORKING PROCESS

14. COURSE: MFP UNIT: 1 Pg. 14
WARM (OR) SEMI HOT WORKING
 Defined as the plastic deforming a metal / alloy under condition of temperature
and strain rate, such that the draw backs of both cold working and hot working are
eliminated and their advantages are combined together
 To achieve this selection of proper temperature is very impotant
 This depends on the following factors
1. Yield / flow strength
2. Ductility
3. Dimensional tolerance of components
4. Oxidation and scaling losses

15. COURSE: MFP UNIT: 1 Pg. 15
DIFFERENCES B/N COLD WORKING & HOT WORKING
SNO Cold working Hot working
1 Done at temperature below
the re crystallization
temperature
Done at temperature above the
re crystallization temperature
2 Less mechanical properties of
metals
High mechanical properties of
metals
3 Crystallization does not takes
place
Crystallization takes place
4 Material is not uniform after
this working
Material is uniform through out
5 More risks of cracks Less risk of cracks
6 High UTS, yield point hardness
but decreases resistance to
corrosion
UTS, yield point corrosion
resistance are un effected
7 Internal stresses and residual
stresses are produced
Internal stresses and residual
stresses are not produced