Edited by: S. Ekinović; S. Yalcin, J. Vivancos Journal of Trends in the Development of Machinery and Associated Technology Vol. 18, No. 1, 2014, ISSN 2303-4009 (online), p.p. 59-62 INFLUENCE OF COOLING FLUID APPLICATION ON TOOL WEAR DURING MACHINING OF HARDENED CHROME NICKEL STEEL Muhamed Mehmedović University of Tuzla, Faculty of Mechanical Engineering Tuzla, Bosnia and Herzegovina Sabahudin Ekinović University of Zenica, Faculty of Mechanical Engineering Zenica, Bosnia and Herzegovina Emir Šarić University of Tuzla, Faculty of Mechanical Engineering Tuzla, Bosnia and Herzegovina Samir Butković University of Tuzla, Faculty of Mechanical Engineering Tuzla, Bosnia and Herzegovina ABSTRACT Influence of cooling fluid application on the tool wear, during longitudinal turning of hardened chrome nickel steel, on the basis of experimental investigations is presented in this paper. Cutting tool wear investigation through comparation dry machining and machining by cooling fluid application, for the same other machining conditions, are conducted. Tool wear size, tool wear shape and cutting tool life are taken into account by cutting tool wear investigation. Analysis of experimental results showed inverse proportion between coolig fluid application and flank wear size, as well as significance of influence on tool wear and its characteristics, via the flank wear shape. Also, analysis of experimental results showed significance of influence coolig fluid application on increase of cutting tool life. Key words: turning of hardened steel, tool wear size, tool wear shape, cutting tool life 1. INTRODUCTION Machining of hardened materials, in the most cases, without cooling fluid application are performed. As for ecological aspect, it is one of the most advantage of this machining process with regard to conventional machining processes. Scientific papers that explore these issues, as well as manufacturers of cutting tools for this type of application processing, mainly favored treatment without the use of coolant . According to their opinion, the use of coolant does not give desired effect on the cutting process, and if the coolant is used, it only represents additional production costs. Influence of cooling fluid application on the tool wear, during longitudinal turning of hardened chrome nickel steel, on the basis of experimental investigations is presented in this paper. Cutting tool wear investigation, through comparation dry machining and machining by cooling fluid application, for the same other machining conditions, are conducted. Tool wear size, tool wear shape and cutting tool life are taken into account by cutting tool wear investigatio. Analysis of experimental results showed inverse proportion between cooling fluid application and flank wear size, as well as significance influence on tool wear and its characteristics, via the flank wear shape. Also, analysis of