ROLLING

                                                              

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.

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