State of the art in hard turning Gaurav Bartarya a,n , S.K. Choudhury b,1 a Mechanical Engineering Department, Harcourt Butler Technological Institute, Kanpur 208002, India b Mechanical Engineering Department, Indian Institute of Technology, Kanpur 208016, India article info Article history: Received 6 June 2011 Received in revised form 24 August 2011 Accepted 25 August 2011 Available online 29 September 2011 Keywords: Hard turning Machining White layer Tool wear abstract Hard turning is gaining grounds for machining hardened steels as it has several benefits over grinding. There are several issues, which should be understood and dealt with, to achieve successful performance of the process. Researchers have worked upon several aspects related to hard turning. The present work is an effort to review some of these works and to understand the key issues related to process performance. The review shows that the type of tool material, cutting edge geometry and cutting parameters affect the process efficiencies in terms of tool forces, surface integrities integrity, and white layer. Adequate machine rigidity is a must essential to minimize the process inaccuracies. Also moreover, for finish hard turning, where the depth of cut is less than the nose radius of the tool, the forces deviate from the conventional trends as the radial force component is the maximum and axial force component becomes minimum. The present work finally lists down certain areas that can be taken up for further research in hard turning. & 2011 Elsevier Ltd. All rights reserved. Contents 1. Introduction ........................................................................................................ 1 1.1. Limitations of hard turning ...................................................................................... 2 2. Literature review .................................................................................................... 2 2.1. On cutting edge geometry ....................................................................................... 2 2.2. On tool wear and tool life in hard turning .......................................................................... 3 2.3. Forces in hard turning .......................................................................................... 6 2.4. Force and temperature modelling ................................................................................. 6 2.5. White layer in hard turning...................................................................................... 7 2.6. Surface integrity and fatigue life .................................................................................. 9 2.7. Lubrication and cooling methods ................................................................................ 11 2.8. Regarding accuracy of the process ............................................................................... 11 3. Conclusions ....................................................................................................... 12 References ........................................................................................................ 12 1. Introduction Hard turning is performed on materials with hardness within the 45–68 Rockwell range using a variety of tipped or solid cutting inserts, preferably CBN. Although grinding is known to produce good surface finish at relatively high feedrates, hard turning can produce as good or better surface finish at signifi- cantly higher material removal rates. Although the process is performed within small depths of cut and feedrates, estimates of reduced machining time are as high as 60% for conventional hard turning [1]. Studies have shown that using the right combination of insert nose radii, feedrate or the new insert technology, hard turning can produce better surface finish than grinding. Multiple hard turning operations may be performed in a single setup rather than multiple grinding setups (Fig. 1). This also contributes to high accuracy achieved by hard turning. Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/ijmactool International Journal of Machine Tools & Manufacture 0890-6955/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijmachtools.2011.08.019 n Corresponding author. Tel.: þ919450612482. E-mail addresses: bartarya@iitk.ac.in (G. Bartarya), choudhry@iitk.ac.in (S.K. Choudhury). 1 Tel.: þ919935028406. International Journal of Machine Tools & Manufacture 53 (2012) 1–14