Rolling process

Rolling principle -

The principle of Rolling is based on the process in which the metal is deformed under compressive force when it placed between the two rollers.

Type of rollings process-

1. Hot rolling 
2. Cold rolling

Hot rolling -

Hot rolling is a permanent metal deformation process which involves rolling the metal at a high temperature, generally above the critical temperature.
             Hot rolling is necessary for harder items, like metal, in order to make it possible to roll the item. While the exact temperature and certain specifics can vary from one hot rolling process to another, it generally is going to utilize the same basic procedure. This way, the metal can be heated, stretched and rolled up, all so it is possible to provide the highest quality product in a roll that is easy to transport.
            In this process, metal is heated in the furnace according to the type of material ( for steels 1100 degree Celsius). Now the heated material comes in contact with rolling mills where two or more rollers exert the compressive force on the material hence the material deform due to the compressive loads.

Actual hot rolling in industries

Hot rolling improves-

• Toughness and strength
• Ductility
• Weldability
• Resistance to vibration and shock
• Formability

Advantages of hot rolling-

• When the metal is in the plastic stage at that time we can see large deformation
• We can notice that the porosity of the metal must be minimized
• Impurities are broken and spread through the metal
• Metal consists of the grain structures that are polished
• The physical proprieties must be improved.

Disadvantages of hot rolling -

• Due to high temperatures, oxidation takes place on the surface of the metal
• Due to oxidation surface finish must be poor and metal loss.
• Tolerance maintenance is not possible.
• High amount of tool cost for the process.

Cold Rolling process-

The cold rolling is the process in which the material is deformed under pressure ( applied by rollers) at room temperature or we can say less than the critical temperature of the material.

cold rolling we can produce the products like sheets, bars, rods, strips etc.

it can process only smaller material as compared to hot rolling. The advantage is that it reorients the grains and give a good finishing. 

Advantages of cold rolling-

• Gives good surface finish
• Easy to handle the materials
• Compare to the hot rolling process dimensional control is possible in cold rolling
• There is no oxidation process takes place in the process so the high surface finish is possible.
• Hardness and strength of the material is increased

Disadvantages of cold rolling

• By using the cold process we can process the ductile material only
• small deformation takes place in this cold working process.