Proceedings of SerbiaTrib '13

where is I i machinability index of i-th material, p iparameter value accepted for machinabilityevaluation of i-th material, p r parameter valueaccepted for machinability evaluation of referentmaterial.Figure 24. Models of parameters roughness for theconventional technique of CLF dosingFigure 26. Values of machinability index based onenergy aspectFigure 25. Models of parameters roughness for theMQL techniqueIf the analysis is carried out from the aspect ofmaterials machinability, R y is a more relevantfactor than R a , because parameter R y indirectindicator of process condition and a direct indicatorof quality as well (Fig. 24 and 25). R y models basedon regression analysis are presented in the form ofthe function of tool wear VB, feed f and the radiusof the tool tip r for both CLF dosing techniques.The second part of this function is taken from theknown empirical expression for the theoretical levelof roughness.Comparison of material machinability was madefor both lubrication techniques under consideration.Machinability index of i-th material in regard toreferent material is defined as:±( p / p ) 1 ⋅100%I =(1)iirFigure 27. Values of machinability index based on thetool life aspectFigure 28. Values of machinability index based onsurface roughness aspectExponent of ratio p i /p r has value of +1 in casethat increase of chosen parameter has positiveeffect on machining process development;otherwise it is a -1 if effect is negative. Results of300 13 th International Conference on Tribology – Serbiatrib’13