Low-frequency chatter genesis during inclined surface copy-milling with ball-end mill: experimental study

In this study low-frequency chatter during machining of inclined surfaces with ball-end mills is experimentally investigated. An explanation of genesis of low-frequency vibrations have been proposed for various conditions: cutting direction, lead angle values, spindle speed, depth of cut. As a result, it has been proven that low-frequency chatter has more significant effect on machined surface than usual chatter. Low-frequency chatter occurs during downward milling, rather than upward milling, especially when lead angle increases. Furthermore, low-frequency chatter takes place in the beginning of cutting process, thereafter develops into steady state of usual chatter, which has no such significant effect on machined surface, as it has been shown. The results are in line with the supposition that low frequency vibrations are caused by sudden and irregular nature of shearing process, when magnitude is small

Stability of ball-end milling on warped surface: semi-analytical and experimental analysis

This paper presents a study of warped surface machining with ball-end milling. A specific model based on the classical stability lobe theory was used and improved with important aspects. The non-linear effect of radial allowance on the contact angle was integrated by an original averaging method. The cutting coefficients are updated in order to follow effective radius and cutting velocity. An original experimental procedure was developed in order to compute the cutting coefficient for various inclined surfaces. More complete experimental analysis was conducted in order to study the effect of machining parameters on the stability of inclined surface milling. The comparison between experiment and simulation shows good correlation for the prediction of stable cutting condition