Rolling
is defined as a process used to reduced
the thickness and to make the thickness uniform.
If the
temperature of metal is above its re crystallization temperature then the
process is known as hot
Rolling
process.
If the
temperature of metal is below re crystallization temperature then it is known
as a cold rolling process.
HOT
ROLLING PROCESS:
It is a
metal working process that occurs above re crystallization which maintain equal
microstructure
And prevents
the metal from work hardening.
CASTING:
Casting is defined as a manufacturing process in which
a liquid material is poured into a mould
which contains a hollow cavity of desired shape and then allow to solidify.
The
solidify part is also known as a casting, which is ejected or broken out of the
mould to complete the process.
TYPES CASTING :
METAL
CASTING
PLASTER,CONCRETE
OR PLASTIC RESIN.
In hot
rolling process the starting point is
usually large pieces of metals like semi finished casting products such as
slabs ,blooms and billets.
Semi finished
casting products are intermediate casting produced in a foundry that required
further processing before being a finished products.
TYPES OF
PRODUCTS
Ingots
Blooms
Billets
Slabs
If these
products came from a continuous casting operation the products are directly fed
into the
Rolling
mills at proper temperature.
As the material is worked the temperature must be monitored to make
sure it remain above
re crystallization temp.
To
maintain a safety factor a finishing temperature is defined above re crystallization
temperature.
If the
temperature does drop below this temperature the material must reheated before more hot rolling.
Hot
rolled mild steel seems to have a wider
tolerance for amount of included carbon than cold rolled steel.
Also hot
rolled products seems to be less costly than cold rolling ones.
Hot
rolling is used mainly to produce sheet metal or simple cross section such as rail tracks.
CONTINUOUS
CASTING
It is
the process where molten metal is solidified into semi finished billets, blooms, slabs for rolling in
finishing mills.
.
