Role of Lubrication during the Process of Metal Working Feb15

Role of Lubrication during the Process of Metal Working...

Role of Lubrication during the Process of Metal Working For understanding the role of lubrication during the processes of metal working, it is important to know the tribology of the lubrication. Tribology consists of boundary friction, which is associated with almost all operations of the metal working. It is caused by the relative movement of two adjacent surfaces under pressure. During the metal working processes, the relative movement between rolls and work piece is improved by the surface speed differential of the rolls Friction Friction plays an important role during metal working process. It is defined as the resistance to relative motion between two bodies in contact. It is an energy dissipating process, causing the temperature at the interface to rise and, if excessive, can result in surface damage. It also influences the deformation taking place in the metal working process. As per the earliest theories, friction is the result of interlocking two rough surfaces sliding along each other. Friction is actually brought on by a large number of variables, such as load, speed, temperature, the materials involved in the sliding pair, and the various effects of fluids and gases at the interface. Most commonly accepted theory of friction is based on the resulting adhesion between the severities of the contacting bodies. It has been seen that regardless of how smooth the surfaces are, they contact each other at only a fraction of their apparent area of contact. Thus, the load during the process of metalworking is supported with few severities in contact. Hence, the normal stress at the severity junctions is high. Under light loads, the contact stresses can only be elastic. However, as the load increases to some of the levels involved in the metal working process, elastic deformation of the severities...