FORGING 2015-16 Rohan Desai, Automobile Engg. Dept, NPK. Page 1 Topic and Contents Hours Marks 1.1 Introduction: 08 Marks Forgeable materials and forgeability Classification of forging processes Advantages and limitations of forging processes 1.2 Forging sequences for Auto components- 08 Marks Connecting rods, Crankshafts, Camshafts and Spanners 06 16
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FORGING 2015-16
Rohan Desai, Automobile Engg. Dept, NPK. Page 1
Topic and Contents Hours Marks
1.1 Introduction: 08 Marks
Forgeable materials and forgeability
Classification of forging processes
Advantages and limitations of forging processes
1.2 Forging sequences for Auto components- 08 Marks
Connecting rods, Crankshafts, Camshafts and Spanners
06 16
FORGING 2015-16
Rohan Desai, Automobile Engg. Dept, NPK. Page 2
1. FORGING
1.1 INTRODUCTION:
Forging is an oldest shaping process used for the producing small articles for which
accuracy in size is not so important. The parts are shaped by heating them in an
open fire or hearth by the blacksmith and shaping them through applying
compressive forces using hammers.
It consists essentially of changing the shape and section of metal by hammering at a
temperature of about 980°C, at which the metal is entirely plastic and can be easily
deformed under pressure. The shop in which the various forging operations are
carried out is known as the smithy or smith’s shop.
What is forging? (Define forging)
A. Forging is a plastic flow of metal by the application of compressive forces in
which size and shape is changed permanently without failure.
B. Forging is a deformation process in which work is compressed between two
dies using either impact or gradual pressure to form the part.
� FORGEABLE MATERIALS:
Any material (Metal or Alloy) which can be brought to plastic stage through heating
can be forged.
1. Aluminium alloys
2. Magnesium alloys
3. Copper alloys.
4. Carbon and low alloy steels
5. Martensitic stainless steels
6. Austenitic stainless steels
7. Nickel alloys
FORGING 2015-16
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8. Titanium alloys
9. Columbium alloys
10. Tantalum alloys
11. Molybdenum alloys
12. Tungsten alloys
13. Beryllium.
Q. What are the properties of the forgeable materials? (List the desirable
properties of forgeable materials)
1. Strength
2. Malleability
3. Resistance to fatigue
4. Durability
5. Shock or bending resistance
6. Machinability
� FORGEABILITY.
“The ease with which forging is done is called forgeability.” The forgeability of a
material can also be defined as the capacity of a material to undergo deformation
under compression without rupture. Forgeability increases with temperature up to a
point at which a second phase appears or if grain growth becomes excessive.
Certain mechanical properties are also influenced by forgeability. The pure metals
have good malleability and thus good forging properties. The metals having high
ductility at cold working temperature possesses good forgeability.
FORGING 2015-16
Rohan Desai, Automobile Engg. Dept, NPK. Page 4
� CLASSIFICATION OF FORGING PROCESS:
� ADVANTAGES & DISADVANTAGES OF FORGING
Advantages:
1. Uniformity of qualities for parts subject to high stresses & loads.
2. Weight saving
3. Close tolerance
4. Less machining
5. Smooth surface
6. Speed of production
Disadvantages:
1. High tool cost
2. High tool maintenance
3. No cored holes
4. Limitations in size & shape.
FORGING 2015-16
Rohan Desai, Automobile Engg. Dept, NPK. Page 5
Q. How the forging is carried out in open dies?
Forging work is produced between flat faced dies. Small no. of light Forgings are
done by hand on an anvil. Hence it is also called as smith forging, but heavy and
medium forgings are done by power hammers and presses. Smith forging or open
die forging processes produce work pieces of lesser accuracy than impression or
closed die forging. Following are sub types of smith die forging,
1. Hand forging: It is done by hammering the piece of metal, when it is
heated to the proper temperature, on an anvil. While hammering the metal is
held with suitable tongs. Formers are held on the forging by the smith while
other end is struck with a sledge by a helper.
2. Power forging: Large machine parts are forged by power forgings.
Power forging takes less time than hand forging to complete the operation.
Machines which work on forgings by blow are called “hammers”, while those
working by pressure are called as “presses”.
a. Hammer forging: All power hammers employ the same general principle
of operation, a falling weight striking the blow, with the entire energy
being absorbed by work.
b. Power press: They are usually of the hydraulic type. The water passes
from a large capacity tank to a pump and then is delivered on the
press with the aid of an accumulator and distributor.
FORGING 2015-16
Rohan Desai, Automobile Engg. Dept, NPK. Page 6
Q. How the forging is carried out in impression dies?
Most complex shape of greater accuracy is formed by closed die forging techniques.
Since die is not fully closed hence it is called as impression die. It is carried out in
following dies
1. Drop hammers: They are used in making drop forgings. Board or
gravity, air lift and power drop hammer are the types of drop hammers.
2. Press forging: the action of working is relatively slow squeezing instead
of delivering heavy blows and penetrates deeply because it gives the metal
time to flow. The press forging dies require a mechanical means for ejecting
the forging. There are two types of presses,
a. Hydraulic press
b. Mechanical press
FORGING 2015-16
Rohan Desai, Automobile Engg. Dept, NPK. Page 7
Q. What do you mean by machine or upset forging?
Bolts, nuts, washers, collars, pinion and gear blanks are produced in machine or
upset forging.
Q. State & explain various operations carried out in forging process.