The Mechanism of Lubrication in Hot Rolling Process
Hot rolling is a process in which metallic material is heated to above its recrystallization temperature and is formed into shapes by passing through successive rolling mills. The process produces strong, consistent metals in all types of shapes and forms. Hot rolling is also a cost-effective solution for producing large volumes of product quickly. In order for hot rolled products to meet stringent tolerances, lubrication is often used to ensure accuracy and reduce friction. This article will discuss the mechanism of lubrication in the hot rolling process.
Lubrication is used in hot rolling to reduce friction and wear between the rolling surfaces. Friction between the workpiece and the rolls cause heat to be generated, which can result in work hardening and deformation of the material being hot rolled. This can lead to uneven surfaces, concerns in dimensional control, and decreased efficiency. By reducing the friction, the desired surface finish can be achieved while also increasing process efficiency.
The mechanism of lubrication in the hot rolling process is the reduction of the coefficient of friction between the surface of the workpiece and the surface of the rolls. Various lubricants can be used, such as graphite, waxes, and liquid lubricants. Each lubricant has its own characteristics that must be taken into account when selecting the appropriate lubricant for a specific application.
The most commonly used type of lubricant for hot rolling is graphite. Graphite is a soft, slidable lubricant, consisting of fine particles of graphite that are applied to the surface of the material being rolled. When the workpiece and rolls come into contact, graphite particles are forced into the microscopic spaces between the two surfaces. This creates a slippery film that reduces friction, resulting in reduced work hardening, increased dimensional control, increased efficiency, and improved surface finish.
Another type of lubricant used in hot rolling is wax. Waxes are often preferred over graphite because of their ability to provide a more uniform coating on the surface of the workpiece while reducing heat generation. Waxes also have a lower tendency to clog the rolls and cause excessive surface fouling. Additionally, waxes are less expensive than graphite.
The third type of lubricant used in hot rolling is liquid lubricants. This type of lubricant can be used as a pre-lubricant prior to rolling or as a rolling oil during the process. Liquid lubricants typically consist of oil, emulsifier, additives, and water. They provide excellent lubrication and cooling of the workpiece during hot rolling.
In conclusion, lubrication is essential in the hot rolling process to reduce friction, work hardening, and deformation of the material being rolled. Lubricants such as graphite, waxes, and liquid lubricants are used to achieve a smooth and accurate surface finish while also improving process efficiency. All types of lubrication have their own characteristics and must be chosen carefully to ensure the best results.
