Determination of minimum uncut chip thickness in mechanical micro-machining using Johnson-Cook fracture model

摘要

In mechanical micro-machining (MMM), the tool edge cannot be considered to be sharp due to the finite edge radius observed at the micro-scale. The uncut chip thickness is comparable to the tool edge radius and sometimes it is less than the tool edge radius. In MMM, below certain critical uncut chip thickness, only elastic deformation takes place and no chip is formed. This is known as minimum chip thickness effect. This affects the machining process significantly and needs to be understood properly in order to develop a successful force model. In the present work, a finite element model using Johnson-Cook fracture model is developed to find the minimum uncut chip thickness in MMM which takes into account the material properties and tool edge radius. It is estimated from the height of the element layer required ahead of the tool for no chip formation. From the simulations, the minimum uncut chip thickness (MUCT) has been found which is in the order of values available in literature.