Surface finish improvement in ball nose end milling by optimizing operating conditions for different cutting times

Abstract

<span style="font-size: 9.0pt;mso-bidi-font-size:10.0pt" lang="EN-US">An important problem of ball nose end milling is degradation of the quality of machined surface for long run machining due to rapid tool wear. In this work, a practical solution to this problem by employing designed experiments (DOE) and response surface methodology (RSM) to determine optimal operating conditions with different tool cutting times is proposed. The significant cutting process factors and corresponding optimal operating conditions are found to depend on the cutting time. The machined surface finish produced by tools with different cutting times <span style="font-size:9.0pt;mso-bidi-font-size:10.0pt;mso-bidi-language: TH" lang="EN-US">are verified by confirmation experiments and evaluated by pair comparison method<span style="font-size:9.0pt;mso-bidi-font-size:10.0pt" lang="EN-US"> at the optimal and non-optimal operating conditions<span style="font-size:9.0pt;mso-bidi-font-size:10.0pt;mso-bidi-language:TH" lang="EN-US">. The results show that the optimal operating conditions of the process factors are different when machining with different cutting times. <span style="font-size:9.0pt;mso-bidi-font-size:10.0pt" lang="EN-US">Surface roughness values are low and insignificantly different over a wider range of cutting time when machining at the optimal operating conditions. On the other hand, there are significant differences in all pair comparisons under non-optimal operating conditions. In addition, electron microscopic characterization confirmed that severe notch tool wear would not occur within short cutting time if the tool is operated at the optimal conditions. Therefore, the surface quality of machined parts as well as tool life could be effectively improved by the use of optimal operating conditions as a function of cutting time obtained by DOE and RSM.

</span></span></span></span></span>