Punching and Forming Production Line: Cold Rolling and Hot Rolling

Steel coils are finished steel products, such as sheet or strip, that have been rolled and then coiled or wound. There are two types of processes for making steel coils: cold rolling and hot rolling. HAVEN introduces them for you.

Cold Rolling Method

Cold working is a metal forming method that offers many advantages over hot working. Technically speaking, cold working includes cold rolling and cold drawing. The former is a process used in conjunction with sheet metal. The latter can be used for rectangular and round bars.

Cold rolling is performed when the metal is below its recrystallization temperature. This is still only half of the truth. The whole process starts just like hot rolling, giving the initial shape without much resistance. After that, the metal is cooled at room temperature.

The semi-finished product is then fed into a cold rolling mill. The metal is rolled to a thickness of a few millimeters. The material is cooled by using oil, which also acts as a lubricant during the rolling process. As the sheet of metal between the rolls becomes thinner, its speed increases. Cold rolled steel can be identified by its oily and smooth surface.

Strain hardening occurs when the process is carried out at temperatures below the recrystallization temperature. Rolling causes plastic deformation. As a result, the yield strength of cold rolled steel is higher than that of hot rolled steel.

Main advantages: precise finished dimensions, clean surface, higher strength characteristics.

Check this to see our production line: https://youtu.be/Bp6Hv7vT8tM

Hot rolling method

Hot processing is more widely used than cold processing because it requires less force and energy. It is used in compression forming methods such as calendering, metal extrusion, and forging. Hot rolling is performed at a temperature higher than the recrystallization temperature of the material. In the case of steel, the temperature rises above 1000°C.

The raw material is usually steel billets or billets. First, they are heated above the above temperature. The next step is to feed them into the rolling machinery. Continuous rolling provides the desired final shape - metal sheets (3 mm and above) or profiles.

Advantages and disadvantages: Since metal is easily formed at high temperatures without any additional delay, it can be produced in larger quantities than cold-rolled steel. This makes the market price of hot-rolled steel lower. However, hot rolled steel does not have the best quality. It shrinks slightly during cooling, and in addition, hot rolled products are easily identified by touching the surface due to their uneven finish, but also lack an oil film.

When choosing the right material for your product, be sure to understand the difference between these two methods of manufacturing. When not too demanding, hot-rolled steel is a better choice. Otherwise, use cold-rolled steel. Contact us now for a quote, we offer a complete line of steel coils.