Int J Adv Manuf Technol (2013) 68:365–374  

DOI 10.1007/s00170-013-4734-2

A numeric investigation of friction behaviors along tool/chip interface in nanometric machining of a

single crystal copper structure
Chunhui Ji, Jing Shi*, Yachao Wang,  Zhanqiang Liu

Abstract: The interaction between the tool rake faceand the chip is critical to chip morphology, cutting forces, surface quality,and other phenomena in machining. A large body of existing literature on nano-metricmachining or nano-scratching only considers the overall friction behavior bysimply regarding the total force along tool movement direction as the friction force,which is not suitable for describing the intriguing friction phenomena alongthe tool/chip interface. In this study, the molecular dynamic (MD) simulationis used to model the nano-metric machining process of single crystal copperwith diamond tools. The effects of three factors, namely, tool rake angle,depth of cut, and tool travel distance, are considered. The simulation resultsreveal that the normal force and friction force distributions along tool/chipinterface for all cases investigated are similarly shaped. It is found that thenormal force consistently increases along the entire tool/chip interface when amore negative rake angle tool is used. However, the friction force increases asthe rake angle becomes more negative only in the contact area close to the tooltip, and it reverses the trend in the middle of tool/chip interface. Meanwhile,the increase of depth of cut overall increases the normal force along thetool/chip interface, but the friction force does not necessarily increase. Also,the progress of tool into the work material does not change the patterns ofnormal force, friction force, or friction coefficient distributions to a greatextent. More importantly, it is discovered that the traditional sliding modelwith a constant friction coefficient can be used to approximate the latersection of friction distributions. However, no friction model for traditional machiningis appropriate to describe the first section of friction distributions obtainedfrom the MD simulation.

Keywords: Friction. Nano-metric machining. Molecular dynamic simulation. Tool/chip interface

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