HOT WORKING AND COLD WORKING PROCESSES
1) COLD WORKING PROCESS :
Working of
alloys or metals below the re-crystallization temperature is called as cold
working process, note that the re-crystallization temperature range for alloys and
metals may 340°c to 400°c and 400°c to 700°c respectively.in cold working
process the grains of the material is twisted or destroyed.
The tensile
strength and hardness of the material is increases by cold working process. The
main advantage of hot working process is to control dimensions under tolerance.
No formation of crystals during process Surface finish in cold working process is
good, cost required for cold working process less as compared to hot working
process. This process required more force as compared to hot working process.
Some of
process of cold working shown below,
1 A) Cold
Rolling Process :
Pic01
This
process in which the sheet metal is squeezed between rollers. This process
increase the yield and hardness of the material.
Advantages :
I) Fast speed of
material forming
II) Produced large
plastic deformation.
III) Improve yield
B) Bending Process :
Pic02
Pic02
Bending is the process in which the V shape, U shape or any required shape of
material so the bending process is change the shape of the material as per
requirement but volume is remain same.
Advantages :
I) We can make shape
of the material as per requirement.
II) Cost effective
process.
C) Wire
Drawing Process :
Pic03
Pic03
Wire drawing process is differed from other processes by
reducing the cross section of the wire by single or multiple dieses. This
process find their application in many areas. The wire is pulled through die
and cross section of wire is reduces.
Advantages :
I) Provide require
shape of the material as per requirement.
II) Improving tensile
strength of the material
2) HOT WORKING PROCESS :
working of alloys or metals above the re-crystallization temperature is
called as hot working process. In hot working process the micro-structure of
material shows refine grains.
The energy
required for deformation of material less because at high temperature as result
the material becomes soft by . The main disadvantage in this process is due to
oxidation at high temperature due to which the surface finish is not good,
cost required for hot working process high as compared to cold working process.
The lower limit of hot working temperature determine by re-crystallization temperature
main point in hot working process is maintaining the temperature of the
material.
Shown below some of hot working processes,
1 A) Hot Rolling Process:
Pic04
Pic04
As per discuss above the material
is heated above the re-crystallization temperature in operation By this process
we can make required dimensions and geometry of objects with same volume of
metal . Large number of industries is making the hot rolled steel and row
material for different application and operation.
Advantages :
I) Improve
ductility, formability and weldability II) Increase toughness and strength of
the material.
B) Extrusion
process :
Pic05
Pic05
The specific fixed cross section of objects create by extrusion process.in
other words the process in which forcing the material in preshaped die to create
the required shape of objects.
Advantages :
I) Many types of row
material used in extrusion process.
II) Good surface
finish of formed material by this process.
C) Forging
process :
Pic06
Pic06
The object formed by comprehensive forces with required shape is called
forging. Different types of forging processes used as per requirement. With
help of die or power hammer the desire shape of object is formed by forging
process.
Advantages :
I) The product
formed by forging is stronger.
II) Improve mechanical properties & impact
resistance.
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