High Speed Ball-end Milling Research Articles

Sensitivity analysis of cutting parameters considering cutting forces and surface roughness in High Speed Ball End milling process

Sensitivity analysis of cutting parameters considering cutting forces and surface roughness in High Speed Ball End milling process

Generation method and antifriction performance evaluation of discrete micro-pit surface texture based on high speed ball-end milling process

Benefiting from the structural characteristics of the ball-end milling cutter and the tool motion characteristics during the cutting process, the high speed ball-end milling process can be directly used to manufacture discrete surface micro-pits texture with different sizes and distributions. The influencing mechanism of the interval and distribution of the micro-pit texture on the antifriction performance was investigated by combining Fluent fluid simulation and reciprocating sliding friction test under oil immersion lubrication condition. Results show that the textured surface with micro-pit features shows obvious antifriction ability. The friction coefficient of textured surface was reduced by 61.5 % compared with that of polished specimens. The interval can influence the oil film bearing capacity and then the antifriction ability. The most significant friction reduction effect was achieved when the micro-pit interval was 900 μm. Additionally, the friction coefficient can be further reduced by optimizing the distribution of the micro-pits. The friction coefficient decreased to 0.121 for the orientation angle 70° condition.

Optimization of cutting forces in high-speed ball-end milling using fuzzy-based desirability function approach

Optimization of cutting forces in high-speed ball-end milling using fuzzy-based desirability function approach

Formation mechanism of surface defect during high-speed ball-end milling process of hardened die steel Cr12MoV

Formation mechanism of surface defect during high-speed ball-end milling process of hardened die steel Cr12MoV

Dynamic simulation and experimental study of cutting force by rake angle of multi-axis high-speed ball-end milling tool

Dynamic simulation and experimental study of cutting force by rake angle of multi-axis high-speed ball-end milling tool

Tool path selection for high-speed ball-end milling process of hardened AISI D2 steel based on fatigue resistance

This paper aims at revealing how tool paths influence the fatigue resistance of high-speed ball-end hard milled surfaces and proposing corresponding tool path selection methods. Three kinds of tool paths (tool paths A, B, and C with angles relative to the length direction of cuboid workpiece 0°, 90°, and 45°, respectively) were utilized during high-speed milling process of hardened AISI D2 steel. The fatigue resistance of samples for different tool paths was evaluated through three-point bending fatigue tests. Results shows that tool paths have significant effect on fatigue resistance, and the maximum discrepancy in fatigue life can reach about 37.6% for different tool paths. Samples for tool path C shows the longest fatigue life when radial depth of cut ae = 0.1 mm. However, with the further increase of ae, samples for tool path A have the best fatigue resistance, followed by tool path C and B. Microscopic stress concentration and effective residual stress are the main ways by which tool paths influence the fatigue resistance. Changing tool paths leads to the difference in surface topography orientation and then in degree of microscopic stress concentration. Moreover, the effective residual stress (residual stress component in direction parallel to cyclic tensile stress) is also directly determined by tool paths. Tool path selection methods are put forward based on the aforementioned influence mechanisms. This study indicates that improving the fatigue resistance of high-speed ball-end hard milled surfaces suffering given cyclic tensile stress is feasible by choosing appropriate tool paths.

Optimization analysis considering the cutting effects for high-speed five-axis down milling process by employing ball end mill

As one of the advanced manufacturing technologies, high-speed five-axis ball end milling has been widely used in high-end manufacturing fields because of its high efficiency, high quality, and high precision. Based on the analysis of cutting effect and response surface methodology, a series of experiments were carried out. Based on geometric modeling and numerical simulation, various tool postures are comprehensively analyzed, and the down milling process combining positive tilt angle and positive lead angle can achieve better cutting effect. The variance and interaction of the important factors affecting the surface integrity and the cutting process were analyzed, and the polynomial equations reflecting the relationship between the processing index and the input process variable were obtained. Finally, a process optimization schemes with various optimization criteria were proposed. When using a larger tilt, smaller fz and higher spindle rotation speed for multi-objective optimization, a combination of a smaller ap and a smaller ae, or a combination of a larger ap and a smaller ae is advantageous to result in high ideality. The combinations of large lead, large tilt, and high spindle speed give full play to the advantages of high-speed cutting technology. The process optimization plan will help determine the processing strategy for achieving the desired machining results and better surface quality based on actual application requirements. Finally, the future research areas are prospected for the high-performance machining technology.

Experimental Study in Taguchi Method on Surface Quality Predication of HSM

Based on the study of ball milling mechanism and machining surface formation mechanism, the formation of high speed ball-end milling surface is a time-varying and cumulative Thermos-mechanical coupling process. The nature of this problem is that the uneven stress field and temperature field affect the machined surface Process, the performance of the processing parameters in the processing interaction in the elastic-plastic materials produced by the elastic recovery and plastic deformation. The surface quality of machining surface is characterized by multivariable nonlinear system. It is still an indispensable and effective method to study the surface quality of high speed ball milling by experiments.

Modelling and application of response surface optimization to optimize cutting parameters for minimizing cutting forces and surface roughness in high-speed, ball-end milling of Al2014-T6

In this research study, empirical mathematical models for cutting forces and surface roughness have been developed to investigate the effect of axial depth of cut, feed, radial depth of cut and cutting speed in high-speed ball-end milling of Al2014-T6. Ball-end milling experiments have been planned using central composite design based on response surface methodology. The mathematical models have been established and tested for adequacy. A full quadratic model has been adopted for modelling. It has been found that axial depth of cut is the most dominant cutting parameter for the tangential and axial cutting forces, accounting for 49.38 and 47.12% contributions, respectively. Radial depth of cut is the most dominant parameter for radial force and contributes 69.94% for it. Results also revealed that force components decrease with increase in cutting speed. There is very small variation in cutting force components in the cutting speed range of 75–150 m/min at lower values of axial and radial depth of cut. Surface roughness is effected by cutting speed largely followed by feed. Multi-objective optimization has been performed using composite desirability to optimize the cutting parameters for minimum surface roughness and cutting forces simultaneously. Confirmation tests have been conducted using optimal set of cutting parameters. The results of confirmation tests are very close to the predicted results.

Analysis of cutting force coefficients in high-speed ball end milling at varying rotational speeds

ABSTRACTIn high-speed ball end milling, cutting forces influence machinability, dimensional accuracy, tool failure, tool deflection, machine tool chatter, vibration, etc. Thus, an accurate prediction of cutting forces before actual machining is essential for a good insight into the process to produce good quality machined parts. In this article, an attempt has been made to determine specific cutting force coefficients in ball end milling based on a linear mechanistic model at a higher range of rotational speeds. The force coefficients have been determined based on average cutting force. Cutting force in one revolution of the cutter was recorded to avoid the cutter run-out condition (radial). Milling experiments have been conducted on aluminum alloy of grade Al2014-T6 at different spindle speeds and feeds. Thus, the dependence of specific cutting force coefficients on cutting speeds has been studied and analyzed. It is found that specific cutting force coefficients change with change in rotational speed while keeping other cutting parameters unchanged. Hence, simulated cutting forces at higher range of rotational speed might have considerable errors if specific cutting force coefficients evaluated at lower rotational speed are used. The specific cutting force coefficients obtained analytically have been validated through experiments.

Modeling of the instantaneous milling force per tooth with tool run-out effect in high speed ball-end milling

In the high speed milling, the tool run-out affects the cutting force greatly and results in pre-matured tool life. To investigate this relationship, an improved instantaneous milling force per tooth is proposed, with inclusion of tool run-out effect. The un-deformed chip thickness considering tool run-out are defined and modeled, according to the geometrical relationships and axial milling ranges per tooth. Meanwhile, instead of the studying the conventional average flank wear, tool wear per tooth is studied for more sensitive correlation with force. Based on milling tests with Inconel 718, the error of the force model prediction is found less than 1% against the experimental data, and the correlation between the axial instantaneous milling force and tool wear per tooth is above 0.9. The results have shown that the proposed model can accurately describe the instantaneous force per tooth including tool run out effect, and the axial force component is a good indication of tool wear condition.

Analysis of rotational speed variations on cutting force coefficients in high-speed ball end milling

In high-speed ball end milling, cutting forces influence machinability, dimensional accuracy, tool deflection, tool failure, machine tool chatter and vibration, etc. Thus, an accurate prediction of cutting forces prior to actual machining is very much essential for a good insight into the process to produce good quality machined parts. In ball end milling, the cutting forces are proportional to the chip cross-sectional area and constant of proportionalities are referred as cutting force coefficients and they depend on many factors, like cutter geometry, cutting conditions, tool material and workpiece material properties. However, determining these specific cutting force coefficients in ball end milling process is not at all straightforward; rather it is fairly complex. Machining with higher cutting speed affects the chip formation mechanisms and finally causes a significant change in the cutting force coefficients. In the present study, the effect of rotational speeds has been investigated on the cutting force coefficients. A series of experiments have been performed at higher rotational speed. It has been found that the cutting force coefficients are influenced by rotational speed significantly. The results are also verified using experiments.

Process optimization and typical application based on geometrical analysis and response surface method for high-speed five-axis ball-end milling operation

High-speed five-axis ball-end milling operations could achieve high efficiency, good surface integrity, and high accuracy in machining of complex components for many manufacture fields. This work concentrated on the machined surface properties and cutting performance produced by the multi-axis ball-end milling process in order to enhance the high performance application of this technology. Variations of the potential tool–workpiece contact zone; the cutting section area, and perimeter corresponding to eight types of tool posture; and the influence of the different tool postures on the machining characteristics were analyzed by geometrical modeling method. The tool postures with negative tilt angles, positive lead angles, or compound inclination angles with negative tilt angle and positive lead angle are beneficial to improve cutting effects with larger effective cutting speed. Discussions on the response analysis and optimization of the machined surface roughness, surface hardness, and the average and maximum cutting forces were conducted under up milling condition. Furthermore, the multi-objective coupling optimization for process performance and surface integrity and typical application in practical machining were carried out for high-speed multi-axis ball-end milling, and the optimization plans are validated by detection and analysis of the machined surface. The research results would promote the high performance application of the high-speed multi-axis ball-end milling operation.

Optimization of surface roughness in ball-end milling using teaching-learning-based optimization and response surface methodology

Surface roughness is one of the most important requirements of the finished products in machining process. The determination of optimal cutting parameters is very important to minimize the surface roughness of a product. This article describes the development process of a surface roughness model in high-speed ball-end milling using response surface methodology based on design of experiment. Composite desirability function and teaching-learning-based optimization algorithm have been used for determining optimal cutting process parameters. The experiments have been planned and conducted using rotatable central composite design under dry condition. Mathematical model for surface roughness has been developed in terms of cutting speed, feed per tooth, axial depth of cut and radial depth of cut as the cutting process parameters. Analysis of variance has been performed for analysing the effect of cutting parameters on surface roughness. A second-order full quadratic model is used for mathematical modelling. The analysis of the results shows that the developed model is adequate enough and good to be accepted. Analysis of variance for the individual terms revealed that surface roughness is mostly affected by the cutting speed with a percentage contribution of 47.18% followed by axial depth of cut by 10.83%. The optimum values of cutting process parameters obtained through teaching-learning-based optimization are feed per tooth ( fz) = 0.06 mm, axial depth of cut ( Ap) = 0.74 mm, cutting speed ( Vc) = 145.8 m/min, and radial depth of cut ( Ae) = 0.38 mm. The optimum value of surface roughness at the optimum parametric setting is 1.11 µm and has been validated by confirmation experiments.

Analysis Method for Surface Topography Model in High Speed Milling Hardened Steel

During high speed milling hardened steel, the problem that tool vibration reducing machining surface quality causes led to a research for the influence characteristics of milled surface topography through high speed milling experiment. To determine the formation condition of milled surface topography, using displacement increment of origin of tool coordinate system which is caused by the milling cutter vibration and installation error, modifies the cutting motion trajectory. Based on the tool-workpiece contact relationship and the cutting layer parameters of contact points on two teeth, the residual units of machined surface are established, thereby proposing a solution method for the deformation and distribution characteristic of residual units under the overhanging volume and the vibration. Therefore, the milled surface topography of cutting hardness steel with high speed ball-end milling cutter is revealed to bring out a striking contrast between the simulation and experiment of milled surface topography of hardness steel.

Analytical Modeling of Chip Geometry in High-Speed Ball-End Milling on Inclined Inconel-718 Workpieces

Most often contoured surfaces inclined at several inclinations are generated using ball-end milling of aerospace and automobile components. It is understood that the chip morphology and the corresponding cutting mechanisms change with a change in the tool-workpiece interactions on inclined surfaces. Analytical predictive models to accurately evaluate the undeformed and deformed geometries of chip in ball-end milling are not available. Therefore, this work presents development of analytical models to predict the cutting tool-workpiece interaction as the workpiece inclination changes, in terms of undeformed and deformed chip cross sections. The models further evaluate instantaneous shear angle along any cross section of the tool-work interaction on a ball-end cutter in a milling operation. The models illustrate evaluation of a chip segment and mechanism of its formation in ball-end milling on an inclined work surface. It is observed that the chip dimensions, except deformed chip thickness, increase with an increase in the workpiece inclination angle. Also, a higher workpiece inclination results into an easy flow of the deformed chip over the cutting tool flank, which leads to a higher shear angle during the cut. The predictive chip geometry models corroborate 90% to the experimental results obtained at various workpiece inclinations.

Modeling of machined surface quality in high-speed ball-end milling of Inconel-718 thin cantilevers

Machining of thin flexible parts in the aerospace and power industries often involves workpiece deflection majorly influencing the machined surface quality. Very few attempts have been done so far to address issues in the ball-end milling of thin cantilever-shaped parts made of “difficult-to-machine” materials. The objective of this paper is to optimize the machining parameters under the design constraints such as workpiece thickness, workpiece inclination, and cutter orientation to get the best possible machined surface quality. Accordingly, correlations between surface quality and the workpiece deflection have been developed. Independent variables were optimized using a central composite design (CCD) with each variable taken at five levels. All the results were compared with the results obtained by the ball-end milling on flat and horizontal cantilever without an inclination. Analytical models have been developed to predict the instantaneous workpiece deflection, undeformed chip thickness, and width of cut and correlated them with the machined surface quality. The lowest surface roughness of ~1 μm Ra was obtained at a higher cutting speed of 120 m/min and a lower feed rate of 400 mm/min, on thicker workpiece (>5 mm) inclined at an angle of 45° along with the horizontal outward cutter orientation. The dimensional accuracy (width of cut) and the workpiece deflection can be predicted more accurately during ball-end milling of thicker Inconel-718 workpiece inclined at higher angles.

Analysis of Cutting Forces and Optimization of Cutting Parameters in High Speed Ball-end Milling Using Response Surface Methodology and Genetic Algorithm

The stability of the machine tool mainly depend on the cutting force in machining process. In the present study, the influence of cutting speed, feed per tooth, axial depth of cut and radial depth of cut during high speed ball-end milling of Al2014-T6 under dry condition has been studied. Response surface methodology was used for generating the experimental plan for conducting the experiment. The cutting force components i.e. tangential and radial forces were measured and then analysis of variance (ANOVA) was performed. It has been found that the quadratic model is best fitted for prediction of the force components. The analysis of result shows that the cutting forces increases as increase in feed per tooth and axial depth of cut but decreases with increase in cutting speed. Radial depth of cut has significant effect on the cutting force components. The optimization of cutting force components was done by coupling response surface methodology and genetic algorithm. The optimization process was performed in MATLB.

High-speed ball nose end milling of burn-resistant titanium (BuRTi) alloy

Following a brief introduction to aero-engine materials and the development of BuRTi alloy (Ti-25V-15Cr-2Al-0.2C), the paper details a statistically designed machinability experiment involving high-speed ball end milling. Testing utilised 8 mm diameter AlTiN-coated carbide ball nose end mills in a Taguchi L8 fractional factorial design with six factors, each at two levels. Output measures related to tool life/wear, cutting forces, workpiece surface roughness, microstructure and microhardness. Main effect plots, tabulated ANOVA data, percentage contribution ratio (PCR) values together with graphical and SEM data are presented. Use of the lowest material removal rate, high-pressure (70 bar) cutting fluid and a workpiece orientation of 45° resulted in the longest tool life with a machining time of ~60 min; however, surface roughness was poor, and there was smeared/adhered material to a depth of 20 μm. Additionally, carbide fracture/pull-out was observed near the workpiece surfaces whereas microhardness depth profiles from sectioned, mounted and polished samples showed a moderate increase in surface hardness of ~80HK0.25 above the bulk value.

Experiment Research of Cutter Edge and Cutting Parameters Influence on Machined Surface Roughness for High Speed Milling Hardened Steel

By using experiment cutter edge topography obtained by super depth three-dimension microscope, fits the cutter edge curve and calculate experiment cutter edge radius value; by high speed milling hardened steel experiment, individually researches cutter edge and cutting parameters influence on machined surface in high speed milling hardened steel with end-milling cutter and ball-end milling cutter. The experiment analysis results show that under the same cutting parameters condition, machined surface roughness in high speed end-milling cutter milling is better than in high speed ball-end milling; within experiment selected cutting parameter range, cutter edge radius is the main influence factor on machined surface roughness in high speed end- milling hardened steel, while the influence on machined surface roughness in high speed ball-end milling hardened steel is not obvious. In end-milling, when edge radius and milling depth are in the same order magnitude or the difference is not obvious, milling depth should be a little bigger than selected cutter edge radius value.