Hot and Cold Rolls The important thing about a roll form is that it must be exactly what the specifications require it to be.— nothing more, nothing less. There are an extensive variety of tests that are done upon any roll form. For instance, during the roll forming process, ultrasound testing is employed to check for potential flaws and cracks and the tensile durability and hardness of the final product is also tested to ensure that the roll form performs to its full capacity during its actual usage. There are mainly two process by which roll forms can be made—hot rolling and cold rolling. Hot rolling is the most commonly used in which a red hot piece of metal is shaped into a roll form by means of rolls and can then be sent for cold rolling for further shaping. Cold rolling is designed to make the roll form take specific shapes for particular purposes—it is precision rolling. Cold rolling is usually employed in foundries but it can also be employed in other factories from time to time to help shape rolls into a specific cross section. There are basically three kinds of roll forms— •
Foil – This is an extremely thin and wafer like roll. It is highly flexible and ideal for packaging purposes. This is commonly used in the electronics industry as a form of electromagnetic and shock shielding. It may also be employed for foil stamping.
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Sheet – These are relatively thicker and more durable and used extensively in the aerospace, transport and construction sectors. After sufficient conditioning these sheets can be used for airplane manufacturing and construction as well.
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Plate – This is relatively thinner than a sheet but still quite durable. It is also used in similar sectors but mostly used in making cars.
Specialized machinery converts these forms into more particular roll forms to get the desired cross section. Due to the presence of ‘blow holes’ cold forming is necessary rather than shaping or hot rolling the metal directly to the desired shape. Blow holes are basically packets of air trapped inside steel that makes the metal brittle and liable to crack under stress. Blow holes can be removed during hot rolling but cold rolling ensures complete removal. Once the metal is cool it is free from all inconsistencies. These rolls can be then sent for further rolling. Then the roll form can be bent or recut to perfection. For more information, visit our website : http://www.internationalrollforms.com