Plate and sheet are words used to describe the classification of metal depending upon its thickness. While sheet metal is less than 3 mm thick, plate metal is obviously thicker than 3 mm. Many people become confused because of classifications such as plate, sheet, foil and others, but there is no need to be, as their differences are clearly spelt out. It is mostly in terms of metal aluminum that we hear words like plate and sheet.
The thickness of the product decides the category into which it falls or belongs. Plate is defined as a thickness of more than or equal to 0.25 inches, while a sheet has a thickness of 0.006 inches or more but less than 0.25 inches. At the extreme of this continuum is a foil that has a thickness of less than 0.006 inches. These are the three categories that form a bulk of aluminum used in the country in various industries. Aluminum is passed between rolls under extreme pressure to make it thinner and longer in the direction in which it is moving. The amount of pressure that is applied decides which of the three categories the resulting aluminum product will belong. This rolling process can be carried out again and again to turn aluminum into a shape and size which is desired. Rolling process is stopped as soon as we get the desired gage or thickness of aluminum.
The rolling process begins with ingots of metal that are very long and wide and have a thickness of more than 2 feet. There is a breakdown mill that rolls this ingot back and forth in such a manner that its thickness is brought down to a few inches. Further rolling is required to make plates and sheets of the metal. While plate is mostly used in aviation, machinery, and transportation industry, sheet is used to make cans and closures. Plates provide structural sections for ships, railways, military vehicles and trucks. Sheets are widely used in cookware and for other home appliances. It is possible to give various colors to aluminum sheets while plate remains silvery in color. Sheets are used to make license plates of automobiles and also as a base of light bulbs.