Papers by Keyword: Ball-End Milling

Abstract: In case of free form surface milling the quality of the manufacturing is described by the accuracy of the shape and the surface roughness. The 3D surface finishing milling by ball-end milling cutter is one of the most often used machining technologies. In case of ball-end milling the surface roughness can be described theoretically based on the tool diameter and the density of the tool path, but the experience shows than other parameters have effect on the surface roughness. In the article the effect of the different cutting parameters, like feed (f_z), depth of cut (a_p) and width of cut (a_e), is presented in case of plane surface, and the surface roughness is compared with the theoretical roughness, and an estimation method is presented.

Abstract: Optical profiler is employed to measure the surface topography of H-13 die steel machined by ball end cutter. By using 2D discret wavelet decomposition, the topographies of different frequency bands are obtained and the influence of cutter posture on varying frequncy bands topography is studied. The results show that cutter posture has a great influence on the whole frequency band roughness. The changing trend of roughness is roughly the same under different cutter postures which increase firstly then decrease with the decrease in frequency. A surface with a small high frequency roughness may have a large median frequency roughness.

Abstract: Due to the transition region with different hardness, the milling process of assembled hardened steel die is prone to generate flutter, which is hard to ensure surface integrity of workpiece. By establishing the finite element model, the milling process of assembled hardened steel die was calculated by the finite element method. Effects of cutting parameters on milling force and milling temperature were achieved by the above finite element analysis. The laws of the stress and the thermal field distribution in the assembled transition region are analyzed and discovered. The analysis results demonstrate that milling force and milling temperature of the transition region changes in step leaping way. There is a close relationship between processing stability and cutting parameters. The stress and the thermal distribution of the transition region have a significant difference due to the changes in material hardness.

Abstract: Optical profiler is employed to acquire topography height data of ball-end milled die steel surface under different spindle speeds ranging from 2000rpm to 12000rpm with lead angle of 20° and tilt angle of-10°. By multi-scale wavelet analysis, measured height data are decomposed and then been reconstructed, meanwhile 3D topography and 3D roughness in different frequency bands are obtained. The results show that the changing trend of roughness with frequency band under different spindle speeds is not the same. In the high frequency bands, roughness has a tendency to increase with the increasing spindle speed. In the median frequency band, the roughness of the surface machined under low spindle speed 2000 rpm is the largest and the roughness of the surface machined under high spindle speed 12000 rpm is the lowest. In the low frequency bands, the roughness of the surface machined under low spindle speed 2000rpm is much larger than those obtained under other spindle speeds, and with the increasing spindle speed, the changing trend of roughness increases firstly then decreases.

Abstract: This research proposed an in-process tool wear prediction during the ball-end milling process by utilizing the cutting force ratio. The dimensionless cutting force ratio is proposed to cut off the effects of the work material and the combination of cutting conditions. The in-process tool wear prediction model is developed by employing the exponential function, which consists of the spindle speed, the feed rate, the depth of cut, the tool diameter, and the cutting force ratio. The experimentally obtained results showed that the cutting force ratio can be utilized to predict the tool wear of ball-end milling tool. The new cutting tests have been employed to verify the model and the results run satisfaction. It has been proved that the in-process tool wear prediction model can be used to predict the tool wear regardless of the cutting conditions with the highly acceptable prediction accuracy.

Abstract: The surface roughness is monitored using the cutting force and the cutting temperature in the ball-end milling process by utilizing the response surface analysis with the Box-Behnken design. The optimum cutting condition is obtained referring to the minimum surface roughness, which is the spindle speed, the feed rate, the depth of cut, and the tool diameter. The models of cutting force ratio and the cutting temperature are proposed and developed based on the experimental results. It is understood that the surface roughness is improved with an increase in spindle speed, feed rate and depth of cut. The cutting temperature decreases with an increase in tool diameter. The model verification has showed that the experimentally obtained surface roughness model is reliable and accurate to estimate the surface roughness.

Abstract: This article presents the tool wear mechanism when machining Aluminium alloy 6061-T6 with PVD coated carbide under dry cutting condition. Cutting parameters selected were cutting speed, Vc = 115-145 m/min; feed rate fz = 0.15-0.2 mm/tooth and depth of cut, ap = 0.5-0.75 mm. The result showed the tool life of PVD TiAlN ranged from 11 to 97 min. Full factorial approach was employed to exhibit relationship between parameter input and output. From the analysis, cutting speed was found to be the most significant factor for tool performance followed by feed rate and depth of cut. It was also found that most of failure modes occurred were notch wear and flaking near those found near depth of cut line.

Abstract: The paper presents the method of the surveillance of the self-excited chatter vibration. At first, the workpiece modal parameters are estimated based on experimental data which leads to verification of computational model. Then, for selected surface points optimal spindle speeds are calculated. By considering sufficient amount of points it is possible to build a map of optimal spindle speeds. Experimental results show that this map may be used effectively for eliminating chatter in case of the process of ball end milling of a curved flexible detail.

Abstract: In the present study, an attempt has been made to experimentally investigate the effects of the cutting parameters on cutting forces in hard milling of AISI H13 steel with coated carbide tools. Designed based on Taguchi method, four factor (cutting speed, feed, radial depth of cut and axial depth of cut) four level orthogonal experiments were conducted. Three components of cutting forces were measured during hard milling experiments and then variance analysis was performed. Finally, the linear regression model was established.

Abstract: Machining is often performed by a machining center using various cutting tools and conditions for different shapes and materials. Recent improvements in CAM system make it easier for even unskilled engineers to generate NC programs. In the NC program, the end-milling conditions are decided by engineers. However, engineers need to decide the order of the process, cutting tool selection, and the end-milling conditions on the basis of their expertise and background knowledge because the CAM system cannot automatically decide. Data-mining methods were used to support decisions about end-milling conditions. Our aim was to extract new knowledge by applying data-mining techniques to a tool catalog. We used both hierarchical and non-hierarchical clustering of catalog data and also used applied multiple regression analysis. We focused on the shape element of catalog data and we visually grouped ball end-mills from the viewpoint of tool shape, which here meant the ratio of dimensions, by using the k-means method. We also found an expression for calculating end-milling conditions, and we compared the calculated with the catalog values.