Analysis of Cutting Forces From Conventional to High-Speed Milling with Straight and Helical-Flute Tools for Flat-End Milling Incorporating the Effect of Tool Runout

This paper presents a systematic study to analyze the dependence of cutting forces on tool geometry, workpiece material and cutting parameters such as spindle speed, tool engagement and cutting direction in flat-end milling with tool runout. The cutting forces are determined according to a mechanistic force model considering the trochoidal flute path to calculate the undeformed chip thickness, and average cutting force and linear regression model are applied for identifying the coefficients of the force model. A series of milling processes are conducted on AZ31 Magnesium (Mg) alloy and titanium alloy (Ti6Al4V) to analyze the instantaneous cutting force curves, amplitudes of cutting forces and peak forces over a wide range of spindle speeds from conventional to high-speed milling. It is demonstrated that the values of the cutting force coefficients are higher at conventional spindle speed and decrease with an increase in spindle speed, especially when machining Ti6Al4V alloy. For the edge force coefficients, it is observed a slight variation when using cutting tools with different helix angles. Besides, the cutting force amplitudes strongly depend upon the workpiece material. The helix angle has a significant influence on the transverse force amplitude at conventional speed. The forces obtained mechanistically are also substantiated by comparison with measurements.

Characterization and Functional Evaluation of Surface Texture of Micro Eccentric Shaft Based on Multi-index

Micro eccentric shaft has important application in many high-tech fields because of its small specific gravity, material and energy saving. The surface texture generated during processing has an indispensable influence on the surface integrity and the final functional capability. However, due to the micro scale and weak rigidity, it is difficult to characterize the surface texture and evaluate the functionality by traditional quantitative parameters. In order to comprehensively realize the surface texture characterization and functional analysis, a mathematical model is established to analyze the surface texture machined with different cutting tools. AnchorThe machining deformation of the micro eccentric shaft machined during turn-milling with different cutting tools is compensated. Then the surface microscopic profile and functional performance of the surface texture are analyzed by amplitude distribution function (ADF) and bearing area curve (BAC), and the surface texture is also evaluated by fractal dimension, which can avoid the effect of scale and resolution. Furthermore, power spectrum density (PSD) is utilized to analyze the relationship between the process dynamic state and geometrical specification of the surface texture. It is shown that the microscopic height distribution of surface machined by flat end milling cutter tends to be more random and there are more microscopic geometric features than that of the ball end milling cutter. The machined surface obtained by the flat end milling cutter has better load bearing, wear resistance and liquid retention capability.

Influence of dynamic geometric parameters on multi-axis machining processes

By means of experimental, geometric and simulation models, roughness values of third and fourth order deviations are determined. The simulation environment is developed from the integration and simulated verification (ISV) in software NX 11 and the geometric approximations are validated through the analysis confocal microscopy.An experiment design is carried out to determine the influence of the dynamic geometric factors: transverse feed (Ae), lead angle and tilt angle, with a flat end milling tool with 1 mm diameter. In the experiment a 3k factorial model is presented to specify the factor with the greatest influence on the roughness. As a result, an optimum (minimum) roughness value is obtained. The lead angle has a moderate influence. Fourth order deviations are associated with the feed per tooth, with a constant angular speed of 5,000 rpm