Using catalog data mining in support of determining micro end-milling conditions
A growing number of requirements are being placed on micro fabrication using end mills with high operating degrees-of-freedom. In particular, when the minor diameter of the end mill is 1.0 mm or less, the handling of tools becomes difficult because of the influence of the characteristic size effect and bending of the cutting portion. Furthermore, it is hard for engineers to derive the cutting conditions that can serve as indexes in the early stage of end-milling with small minor diameters. To solve this problem, in this research, on a basis of workpiece material characteristics and tool shape parameters, a system that can make instantaneous decisions on the tool shape and cutting conditions to be used was built, and its usefulness was evaluated. This system was developed by applying data mining techniques together with non-hierarchical and hierarchical clustering methods on tool catalog data. The results of the analysis found that the characteristics of the workpiece material were significant in making decisions regarding the cutting conditions for the minor diameter of the end mill. Moreover, the cutting speed was found to have a significant effect on the tool shape parameters, whereas differences as to the processing method (side milling or slotting) did not have a significant effect.
Effect of Tool Tilting Angle on Tool Wear and Surface Roughness in Micro Ball End Milling
This paper describes the effect of the tool tilting angle on the tool wear and the surface roughness in micro ball end milling. The cutting tests of hardened stainless steel were carried out by using of the micro ball end mill with radius of 100mm under the conditions of tilting angle from 0° to 45°. The spindle speed was fixed in a constant of 120,000 min-1. The feed per tooth, axial depth of cut and radial depth of cut were also fixed. The flank wear, the surface roughness and the cutting force were investigated. As a result, the maximum width of flank wear of the micro ball end mill tended to decrease with an increase in the tilting angle of spindle. The surface roughness became almost constant not depending on the tilting angle of the spindle.
Process investigation on meso-scale hard milling of ZrO2 by diamond coated tools
Abstract This paper investigates the feasible machining of zirconium oxide (ZrO2) ceramics, in the hard state, via milling by diamond coated miniature tools (from here on briefly indicated as meso-scale hard milling). The workpiece material is a fully sintered yttria stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP). Diamond coated WC mills, 2 mm in diameter, four flutes and large corner radius (0.5 mm) are chosen as cutting tools, and experiments are conducted on a state-of-the-art micro milling machine centre. The influence of cutting parameters, including axial depth of cut (ap) and feed per tooth (fz), on the achievable surface quality is studied by means of a one-factor variation experimental design. Further tests are also conducted to monitor the process performance, including surface roughness, tool wear and machining accuracy, over the machining time. Mirror quality surfaces, with average surface roughness Ra below 80 nm, are obtained on the machined samples; the SEM observations of the surface topography reveal a prevailing ductile cutting appearance. Tool wear initiates with delamination of the diamond coating and progresses with the wear of the WC substrate, with significant effect on the cutting process and its performance. Main applications of this research include three dimensional surface micro structuring and superior surface finishing.