Design optimization of cutting parameters for side milling operations with multiple performance characteristics

In this paper, a grey relational analysis is applied to a set of two-stage experiments designed to determine the cutting parameters for optimizing the side milling process with multiple performance characteristics. The cutting parameters to be considered are cutting speed, feed per tooth, axial depth of cut, radial depth of cut, overhang length and flank wear of peripheral cutting edge. L₃₆ and L₉ orthogonal arrays are used in the experiments and lower-the-better is used as a qualitative characteristic to evaluate the results. It is found that using the grey relational analysis coupled with a deliberate design of the two-stage experiments is simple and efficient in determining an optimal combination of the cutting parameters. The results of the confirmation test also show that this new approach can greatly improve the cutting performance of side milling process.     

Multi response optimization of machining parameters of drilling Al/SiC metal matrix composite using grey relational analysis in the Taguchi method

This paper presents a new approach for the optimization of drilling parameters on drilling Al/SiC metal matrix composite with multiple responses based on orthogonal array with grey relational analysis. Experiments are conducted on LM25-based aluminium alloy reinforced with green bonded silicon carbide of size 25 μm (10% volume fraction). Drilling tests are carried out using TiN coated HSS twist drills of 10 mm diameter under dry condition. In this study, drilling parameters namely cutting speed, feed and point angle are optimized with the considerations of multi responses such as surface roughness, cutting force and torque. A grey relational grade is obtained from the grey analysis. Based on the grey relational grade, optimum levels of parameters have been identified and significant contribution of parameters is determined by ANOVA. Confirmation test is conducted to validate the test result. Experimental results have shown that the responses in drilling process can be improved effectively through the new approach.     

Grey relational analysis coupled with principal component analysis for optimisation design of the process parameters in in-feed centreless cylindrical grinding

This paper investigates optimisation design of an in-feed centreless cylindrical grinding process performed on EN52 austenitic valve steel (DIN: X45CrSi93). The major performance characteristics selected to evaluate the process are surface roughness, out of cylindricity of the valve stem and diametral tolerance, and the corresponding centreless cylindrical grinding parameters are dressing feed, grinding feed, dwell time and cycle time. In this study, since the process is with multiple-performance characteristics, therefore, the grey relational analysis that uses grey relational grade as performance index is specially adopted to determine the optimal combination of centreless cylindrical grinding parameters. Moreover, the principal component analysis is applied to evaluate the weighting values corresponding to various performance characteristics so that their relative importance can be properly and objectively described. The results of confirmation experiments reveal that grey relational analysis coupled with principal component analysis can effectively be used to obtain the optimal combination of centreless cylindrical grinding parameters. Hence, this confirms that the proposed approach in this study can be a useful tool to improve the centreless cylindrical grinding performance of valve stem in in-feed centreless cylindrical grinding process.     

Determination of optimum parameters for multi-performance characteristics in drilling by using grey relational analysis

The theory of grey systems is a new technique for performing prediction, relational analysis and decision making in many areas. In this paper, the use of grey relational analysis for optimising the drilling process parameters for the work piece surface roughness and the burr height is introduced. Various drilling parameters, such as feed rate, cutting speed, drill and point angles of drill were considered. An orthogonal array was used for the experimental design. Optimal machining parameters were determined by the grey relational grade obtained from the grey relational analysis for multi-performance characteristics (the surface roughness and the burr height). Experimental results have shown that the surface roughness and the burr height in the drilling process can be improved effectively through the new approach .     

Multi-response optimization of machining parameters on red mud-based aluminum metal matrix composites in turning process

This paper presents the findings of an experimental investigation into the effects of cutting speed, feed rate, depth of cut, and nose radius in computer numerical control (CNC) turning operation performed on red mud-based aluminum metal matrix composites. This paper investigates optimization design of a turning process performed on red mud-based aluminum metal matrix composites. The major performance characteristics selected to evaluate the process are surface roughness, power consumption, and vibration, and the corresponding turning parameters are cutting speed, feed, depth of cut, and nose radius. Taguchi-based grey analysis, which uses grey relational grade as performance index, is specifically adopted to determine the optimal combination of turning parameters. The principal component analysis (PCA) is applied to evaluate the weighting values corresponding to various performance characteristics. L9 orthogonal array design has been used for conducting the experiments. The outcome of confirmation experiments reveals that grey relational analysis coupled with PCA can effectively be used to obtain the optimal combination of turning parameters. Hence, this confirms that the proposed approach in this study can be a useful tool to improve the turning performance of red mud-based aluminum metal matrix composites in CNC turning process.     

Grey–Taguchi method to optimize the milling parameters of aluminum alloy

The grey–Taguchi method was adopted in this study to optimize the milling parameters of A6061P-T651 aluminum alloy with multiple performance characteristics. A grey relational grade obtained from the grey relational analysis is used as the performance characteristic in the Taguchi method. Then, the optimal milling parameters are determined using the parameter design proposed by the Taguchi method. Experimental results indicate that the optimal process parameters in milling A6061P-T651 aluminum alloy can be determined effectively; the flank wear is decreased from 0.177 mm to 0.067 mm and the surface roughness is decreased from 0.44 μm to 0.24 μm, leading to a multiple performance characteristics improvement in milling qualities through the grey–Taguchi method.     

Experimental investigation and performance analysis of cemented carbide inserts of different geometries using Taguchi based grey relational analysis

In this work, effect of machining parameters cutting speed, feed rate and depth of cut, geometrical parameters cutting insert shape, relief angle and nose radius were investigated and optimized using Taguchi based grey relational analysis. 18 ISO designated uncoated cemented carbide inserts of different geometries were used to turn practically used automotive axles to study the influence of variation in carbide inserts geometry. Performance measures viz., flank wear, surface roughness and material removal rate (MRR) were optimized using grey relational grade, based on the experiments designed using Taguchi’s Design of Experiments (DoE). A weighted grey relational grade is calculated to minimize flank wear and surface roughness and to maximize MRR. Analysis of variance shows that cutting insert shape is the prominent parameter followed by feed rate and depth of cut that contributes towards output responses. An experiment conducted with identified optimum condition shows a lower flank wear and surface roughness with higher MRR. The confirmation results obtained are confirmed by calculating confidence interval, which lies within the width of the interval.     

Determination of optimum parameters for multi-performance characteristics in turning by using grey relational analysis

Optimization of multi-criteria problems is a great need of producers to produce precision parts with low costs. Optimization of multi-performance characteristics is more complex compared to optimization of single-performance characteristics. The theory of grey system is a new technique for performing prediction, relational analysis, and decision making in many areas. In this paper, the use of grey relational analysis for optimizing the turning process parameters for the workpiece surface roughness and the chip thickness is introduced. Various turning parameters, such as cutting speed, feed rate, tool nose radius, and concentration of solid–liquid lubricants (minimum-quantity lubricant) were considered. A factorial design with eight added center points was used for the experimental design. Optimal machining parameters were determined by the grey relational grade obtained from the grey relational analysis for multi-performance characteristics (the surface roughness and the chip thickness). The results of confirmation experiments reveal that grey relational analysis coupled with factorial design can effectively be used to obtain the optimal combination of turning parameters. Experimental results have shown that the surface roughness and the chip thickness in the turning process can be improved effectively through the new approach. The minimum surface roughness and smallest chip thickness are 9.83 and 0.32?mm, respectively, obtained at optimal conditions of cutting speed, 1,200?rpm; feed rate, 0.06?mm/rev; nose radius, 0.8?mm; and concentration of solid–liquid lubricant (10% boric acid + SAE-40 base oil).     

螺纹铣削切削力有限元分析及试验

为了研究螺纹铣削法加工钛合金螺纹时切削力随切削参数的变化规律,通过对材料本构关系、刀—屑接触及切屑分离准则进行分析,建立了能反映刀具自转、公转及轴向进给运动的三维螺纹铣削模型。利用该模型对每齿进给量和切削速度对切削力的影响进行分析,结果表明:切削力随每齿进给量的增大而增大,随切削速度增加而减小,且每齿进给量对切削力的影响较为显著。通过螺纹铣削试验对所建立的三维铣削模型进行验证,表明所建立模型的误差最大为14%,可满足实际加工需要。     

Multi-objective optimization of surface roughness and cutting forces in high-speed turning of Inconel 718 using Taguchi grey relational analysis (TGRA)

In this paper, a new effective approach, Taguchi grey relational analysis has been applied to experimental results in order to optimize the high-speed turning of Inconel 718 with consideration to multiple performance measures. The approach combines the orthogonal array design of experiments with grey relational analysis. Grey relational theory is adopted to determine the best process parameters that give lower magnitude of cutting forces as well as surface roughness. The response table and the grey relational grade graph for each level of the machining parameters have been established. The parameters: cutting speed, 475?m/min; feed rate, 0.10?mm/rev; depth of cut, 0.50?mm; and CW2 edge geometry have highest grey relational grade and therefore are the optimum parameter values producing better turning performance in terms of cutting forces and surface roughness. Depth of cut shows statistical significance on overall turning performance at 95% confidence interval.     

Optimization of weld characteristics of friction welded AA 6061-AA 6351 joints using grey-principal component analysis (G-PCA)

Friction welding is a solid state joining process in which the quality of welded joint is influenced by the input parameter setting. The objective of the present study is to conduct experimental investigation of the bond strength and hardness of the friction welded joints involving AA 6061 and AA 6351 alloys by conducting experiments designed by Taguchi’s L⁹ orthogonal matrix array. A systematic approach becomes essential to find the optimal setting of friction welding parameters. Hence a new approach named grey-principal component analysis (G-PCA) is presented in which the principal component analysis (PCA) is used to generate weights for the grey relational coefficients obtained in the grey relational analysis (GRA). The results of the confirmation experiment conducted with the optimal setting predicted by the G-PCA have shown improvements in the performance characteristics. Hence G-PCA can be used for experimental welding optimization.     

Multi-response optimization of machining parameters in hot turning using grey analysis

This paper envisages the multi-response optimization of machining parameters in hot turning of stainless steel (type 316) based on Taguchi technique. The workpiece heated with liquid petroleum gas flame burned with oxygen was machined under different parameters, i.e., cutting speed, feed rate, depth of cut, and workpiece temperature on a conventional lathe. The effect of cutting speed, feed rate, depth of cut, and workpiece temperature on surface roughness, tool life, and metal removal rate have been optimized by conducting multi-response analysis. From the grey analysis, a grey relational grade is obtained and based on this value an optimum level of cutting parameters has been identified. Furthermore, using analysis of variance method, significant contributions of process parameters have been determined. Experimental results reveal that feed rate and cutting speed are the dominant variables on multiple performance analysis and can be further improved by the hot turning process.     

球头刀铣削淬硬钢倾斜表面切削力试验研究

采用正交试验方法,使用PCBN涂层硬质合金球头铣刀,对不同铣削参数下的52HRC淬硬钢Cr12MoV倾斜表面进行了铣削试验。研究了各工艺参数对切削力的影响规律。试验结果表明:三向力中,Fz远大于Fx和Fy的切削分力,Fz为主铣削力;切削深度对主铣削力的影响大于进给速度、工件倾角和主轴转速对其的影响;工件倾角16.7°,主轴转速6000r/min,进给速度800mm/min,切削深度0.1mm为优选工艺条件。同时,对比试验表明,采用顺铣方式能有效减小切削力,改善铣削稳定性。本文研究结果对淬硬钢Cr12MoV铣削工艺参数的优化具有一定的参考价值。     

薄壁结构件铣削参数有限元正交优势分析及优化

大型整体薄壁结构件在航空、航天工业中得到了广泛应用。但由于其刚性差,在铣削加工过程中常常出现铣削力过大而引起较大的变形,严重影响工件的加工质量和精度。针对上述问题,提出一种有限元正交优势分析方法,用以优化铣削参数,减小铣削产生的零件变形。该方法采用正交试验设计规划指导有限元铣削加工变形分析的参数方案设计,通过不同方案的计算结果研究分析铣削速度、铣削深度、铣削宽度、每齿进给量对加工变形的影响,得到各铣削要素选择的较好水平;采用优势分析方法对正交试验结果进行处理,得到各铣削要素对加工变形的贡献率,从而确定优化的铣削加工方案。以某薄壁框类零件为例得到了铣削参数的优化组合,经过验证,优化后的试验方案减少了铣削产生的最大变形量,证明了该方法的可行性及有效性。     

Milling force vibration analysis in high-speed-milling titanium alloy using variable pitch angle mill

Chatter may cause fast wear of tools and poor surface quality of the workpieces at high cutting speed and it will happen on different process parameters; how do we select the suitable cutting speed to suppress the chatter? In this paper, a signal analysis method for milling force and acceleration is adopted to identify chatter, which can obtain the results not only in frequency of chatter but also in the contribution for milling force at different frequencies. Through the milling experiment, the machining vibration behaviors of milling Ti–6Al–4V with variable pitch end mill were investigated. Milling force and acceleration signals obtained from experiment were analyzed and compared at stable and unstable milling processes. The experimental results show that when the chatter occurs, milling forces were found to increase dramatically by 61.9–66.8% compared with that of at stable cutting; machining surface quality became poor and machined surface roughness increases by 34.2–40.5% compared with that of at stable cutting.     

Prediction of cutting forces and machining error in ball end milling of curved surfaces -I theoretical analysis

This paper presents a theoretical model by which cutting forces and machining error in ball end milling of curved surfaces can be predicted. The actual trochoidal paths of the cutting edges are considered in the evaluation of the chip geometry. The cutting forces are evaluated based on the theory of oblique cutting. The machining errors resulting from force induced tool deflections are calculated at various parts of the machined surface. The influences of various cutting conditions, cutting styles and cutting modes on cutting forces and machining error are investigated. The results of this study show that in contouring, the cutting force component which influences the machining error decreases with increase in milling position angle; while in ramping, the two force components which influence machining error are hardly affected by the milling position angle. It is further seen that in contouring, down cross-feed yields higher accuracy than up cross-feed, while in ramping, right cross-feed yields higher accuracy than left cross-feed. The machining error generally decreases with increase in milling position angle.     

陶瓷刀具高速铣削4Cr13不锈钢铣削力试验研究

采用单因素试验,分析了切削速度vc、每齿进给量fz和切削深度ap对铣削力的影响规律,结果表明:随着切削速度vc的增大,铣削力减少;随着每齿进给量fz和切削深度ap增大,铣削力增大。同时,设计了4Cr13不锈钢正交试验方案,基于概率统计和回归分析原理,建立了4Cr13不锈钢高速铣削的铣削力模型,对建立的铣削力模型进行了显著性检验,检验结果表明所建立的回归方程呈高度显著检验状态,并对其进行了验证,结果表明该模型与实际情况拟合得较好,故可用其来预测和控制铣削力。     

A SIMPLIFIED CUTTING FORCE MODEL FOR LIGHT-CUT BALL-END MILLING APPLICATIONS

In light-cut milling operations, specific correlations have been identified empirically between the maximum cutting force on a cutter and its associated cutting parameters, and a series of ball-end milling tests for P20 tool steel has been conducted to establish the nature of these correlations. The experimental results indicate that the maximum cutting force on a cutter can be expressed as a logarithmic function of the associated cutting parameters. This paper describes the structure and testing of a simplified cutting force model for planar milling based on these results.     

Critical speed analysis for nonlinear effects of rotor system and ball end milling

The critical speed analysis for nonlinear effects of rotor-bearing system and ball end milling are studied in this paper. The nonlinear cutting force can be calculated by using the Tlusty proposed 3/4 rule for chip thickness. The rotor system is supported by bearings with nonlinear spring effects. The critical speeds obtained from this study are compared with two sets of experimental data to validate the proposed four cases. The effects of design parameters on system dynamic behaviors, including critical speeds and tool displacements under the dynamic cutting forces, are numerically investigated in the time domain. The results show that the critical speeds of system are proportional to the corresponding system natural frequencies, but inversely to the cycle number of tool vibration multiplying by the number of flutes during the cutting time from one flute to another. For the linear system and the nonlinear system with small depth-of-cut under linear cutting force milling, their critical speeds are almost identical. With large feed-per-tooth, the differences of the critical speeds become larger between linear and nonlinear rotor systems and so are the dynamic responses at critical speeds milling. The critical speed under nonlinear cutting force milling is found to be always higher than that under linear cutting force. Furthermore, the chatter stability lobes are studied for various cutting conditions. The intervals between critical speeds increase gradually, and the axial depths of cut of nonlinear system for stability are lower than those of linear system.     

基于模糊分析方法的钛合金插铣加工切削参数优化

合理的切削参数有利于提高刀具的使用寿命和切削效率,因此,进行切削加工过程中的切削参数优化尤为重要。本文以提高钛合金插铣加工效率,减小加工过程中的切削力为目的,对钛合金TC4进行插铣试验。基于切削试验数据,选择切削速度、切削宽度和每齿进给量作为评价因子,以材料去除率与切削力作为评价指标,运用模糊分析方法对切削参数进行综合评价,得出切削参数对综合指标的影响程度从大到小依次为:切削速度、切削宽度和每齿进给量,并实现切削参数的优化,为实际生产加工提供参考依据。