INVESTIGATION OF CUTTING PARAMETER EFFECTS ON SURFACE-ROUGHNESS IN LATHE BORING OPERATION BY USE OF A FULL FACTORIAL DESIGN

The main objective of this study is to investigate cutting parameter e ffects of surface roughness in a lathe dry boring operation. A full fa ctorial design was used to evaluate the effect of six (6) independent variables (cutting speed, feed rate, depth of cut, tool nose radius, t ool length and type of boring bar) and their corresponding two-level i nteractions. In this experiment, the dependant variable was the result ing first cut surface roughness (R(a)). In order to perform all possib le variable combinations, a total of 216 cuts were. The results reveal ed that using short tool length always provide good surface roughness and that only slight improvement on surface roughness can be achieved by properly controlling the cutting parameters and/or the type of bori ng bar used. The results also revealed that using a long tool length m ay results in vibration that could be efficiently controlled by the us e of a damped boring bar. With such a long tool length, the cutting va riables become important factors to control in order to significantly improve surface roughness results with both types of boring bars. A pr ediction model is proposed for each types of boring bar. Both models a re highly significant, p<0.00001, with coefficients of determination o f 0.56 and 0.57 for a standard boring bar and a damped boring bar, res pectively.