Experimental study on micromilling of thin walls

Abstract

In order to study micromilling mechanisms and to achieve better quality thin wall fabrication, experimental studies have been conducted considering micromilling parameters and axial feed times. The influence of key process parameters including feed engagement f z, axial depth of cut a p and radial depth of cut a e on milling forces, dimensional errors and surface roughness are studied by single factor experiments with thin thickness wall fabrication. Then, based on the Taguchi method, key process parameters are optimized. It shows that the significant order of key parameters for milling forces from large to small is a p, a e, and f z. The significant order for dimensional errors is a p, f z, and a e. Validation experiments for thin wall fabrication by the optimized parameters show that suitable axial feed times may reduce the dimensional errors of thin walls. Hence, further micromilling experiments have been conducted with larger axial depth of cut and optimized f z and a e. The results show that dimensional errors of thin walls with the same height first decrease and then increase with the decrease of axial feed times. It proves that there exists appropriate axial feed times for achieving thin walls with lower dimensional errors. The suitable axial feed times have been identified as 3 and 4 for thin walls made of the 304 austenitic stainless steel with the aspect ratios of 12 and 18, respectively. The corresponding dimensional errors are 2.5% and 2.1%, respectively. The study indicates that key process parameters f z and a e can be optimized and a p can be preliminarily decided by micromilling of thin thickness walls. Then, the axial feed times with larger a p are further optimized and decided for thin wall fabrication.