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

Authors: U. Srinivas Rao; L. Vijayaraghavan

Addresses: Manufacturing Engineering Section, Department of Mechanical Engineering, IIT Madras, Chennai – 600 036, India ' Manufacturing Engineering Section, Department of Mechanical Engineering, IIT Madras, Chennai – 600 036, India

Abstract: 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.

Keywords: minimum uncut chip thickness; MUCT; micromachining; FEM; finite element method; chip simulation; tool edge radius; Johnson-Cook; fracture modelling; elastic deformation; material properties.

DOI: 10.1504/IJMMS.2013.057129

International Journal of Mechatronics and Manufacturing Systems, 2013 Vol.6 No.4, pp.367 - 380

Received: 17 Sep 2012
Accepted: 20 Mar 2013
Published online: 12 Jul 2014 *

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