Papers by Keyword: Machining Parameters

Abstract: In this analysis turning parameter optimization is performed during machining AISI D2 steel with uncoated and coated cemented carbide cutting inserts using a hybrid multi-objective optimization technique Grey relational analysis (GRA) and Principal Component analysis (PCA). A L₁₆ Taguchi’s orthogonal array design is selected for basic experimental design considering four levels for the chosen four parameters. Output performance measures viz., tool wear, roughness on finished surface and material removed are evaluated by determining grey relational coefficient, and deriving multi response performance index (MRPI) using principal components. Contribution of coated cutting insert is 72.87% towards the MRPI and 17.15% contribution by feed rate, as determined from Analysis of Variance (ANOVA). Confirmation experiment performed with optimum conditions provides lower tool wear, higher material removal and good surface finish. The MRPI of the confirmation experiment is also confirmed by calculating the confidence interval.

Abstract: The direction of feeding the work piece and cutter rotation determines the type of machining mode either it is up milling or down milling. Each of this machining mode affects the quality of machined surface produced. This paper described the experimental design of down milling operation on a stack of multidirectional CFRP/Al2024. Three cutting parameters were considered namely, spindle speed (N), feed rate (f_r) and depth of cut (d_c). Two level full factorial design was utilized to plan systematic experimental methodology. The analysis of variance (ANOVA) was used to analyse the influence and the interaction factors associated to surface quality. The results show that the depth of cut is the most significant factor for Al2024, and for CFRP the spindle speed and feed rate are significant. Surface roughness of CFRP is found to be at 0.594 μm at the setting of N = 11750 rpm, fr = 750 mm/min and dc = 0.255 mm. Meanwhile for Al2024, the surface roughness is found to be at 0.32 μm. The validation test showed average deviation of predicted to actual value surface roughness is 3.11% for CFRP and 3.43% for Al2024.

Abstract: Modern aircraft structures need to be further integrated and parts to be enlarged, the structural parts which require high accuracy of size, shape, and good deformed surface finish, so digital machining process has become key technology in aviation industry. Machining parameters selection is an important phase of machining process, it has very important influence on the dimensional quality of an aircraft structural part. This paper develops a methodology to get an optimal machining parameters in an aircraft structural part machining process, which can satisfies the quality specifications and minimizes the expected value of the sum of machining costs at the same time. An engineered-based model is adopted to describe the machining process of aircraft structural part firstly and then a quantitative machining parameter evaluation methods driven by cost constraint is proposed, an optimal machining parameter is obtained through a computer experiment model which can explore a large number of machining process parameter alternatives. At last, we illustrate the validity and the significance of the engineered-based machining parameters analysis method for aircraft structural parts by a case study. The results have shown that the proposed method could significantly increase the efficiency of aircraft structural parts machining process.

Abstract: For the problem of the interference between the machining tooth surface and the major flank face, the calculation method of the interference amount is put forward. The interference amount is defined as the distance of the points on the machining tooth surface to the major flank face. The position of the tooth surface and the major flank face is judged using the model of the tooth surface and the major flank face. So the model of interference amount is get. On this basis, impact law of cutter parameters and machining parameters on interference amount is analyzed. As a result the evidence for the reasonable selection of cutter parameters and machining parameters is provided.

Abstract: In order to explore the new way to precision machining of the cylindrical, ELID precision mirror grinding technology are employed to precision ultra-precision grinding experiments. Given ELID precision mirror grinding technology has effectively solved the basis of many of the typical flat-precision machining difficult materials and efficient processing, through the conversion process equipment tools, and optimization of process parameters, obtained when the wheel speed in 16 ~ 20 m / s, when the grinding depth 10μm, cylindrical grinding state is best, which could obtain Ra0.025μm surface roughness of the machined surface.

Abstract: Surface roughness is strongly affected by machining parameters. In the past few decades, many researchers have established the relationship between the surface roughness and machining parameters, but less attention has been paid to tool shape and geometry. In addition, the number of tool flutes was ignored, which affects in vibrations and machining system. Therefore, this study first-time includes the tool flutes in addition to cutting speed, depth of cut and feed rate as independent variables. Firstly, a set of machining experiments were conducted using AA6061 as a work piece material to provide original data. Response Surface Model (RSM) adopted to establish the relationship model of surface roughness and machining parameters using Minitab 16. Based on analysis of variance (ANOVA), the results show cutter flutes has higher significant followed by feed rate, depth of cut and cutting speed which has less significant. Finally, machining parameters were optimized to desired surface roughness, and optimization prediction error has limited values between-0.02 and 0.02μm.

Abstract: In this work, the influence of variation in machining parameters cutting speed, feed rate and depth of cut and geometrical parameters cutting insert shape (included angle), relief angle and nose radius is studied using DEFORM-3D, a finite element simulation software. The cutting tool inserts of various geometries are evaluated to study its performance for varying conditions considering contact temperature and mean stress. Effect of individual parameter is analyzed by varying its value by three different level values, while the other parameter values are set at the optimum condition, likewise for all input parameters. From the results obtained, it is observed that the performances of cutting inserts are good at the optimum level of parametric values than at the other level values.

Abstract: The hemispherical surface has been widely implicated in design of products. Its precise roundness, a key quality characteristic of smaller-the-better, highly depends on the milling quality of the hemispherical mold. In this paper, we study the optimal machining parameters for the roundness of the hemispherical mold processed by the five-axis NC milling machine with a rotatable-tilting table. Four machining parameters, tool’s tilt angle, surface-cutting speed, feeding per tooth, and depth in axial cutting, are considered with their three varied levels selected on the basis of the onsite professional knowledge acquired from weighing the effect of tool interference and the milling capability of machine tools. The material NAK80, one type of plastic mold steels, possessing excellent resistance and dimensional stability is used as experimental test specimens. The experimental results conclude that the optimal measurements of roundness for the concave and the convex hemispherical molds are 0.022 mm and 0.026 mm, respectively.

Abstract: In the light of the characteristic of 300M ultra high strength steel and the feature of orthogonal turn-milling machining,an optimization model of orthogonal turn-millng machining parameters is consisted of maximum tool life,minimum surface roughness and maximum productivity. Based on multi-objective optimazation algorithm which is applied in coupling particle swarm optimization algorithm and gray relevancy analysis,it can achieve the purpose which is above mentioned. By introducing the chatter stability lobe diagram of aircraft landing gear with orthogonal turn-milling which is conformed with DMG turn-milling machine tool,it can optimize the parameters of the orthogonal turn-milling machining of the aircraft landing gear with high efficiency and good quality.

Abstract: Assessment of process capability enables manufacturers to determine if a process produces products that meet customers expectation. Process capability can be beneficial in the long run in producing quality parts with minimum reject and optimum manufacturing cost. This paper proposes a procedure to assess process capability of a machining centers in drilling process using statistical analysis of machining parameters and machine rigidity. Experimental method used mild steel plate as work piece and carbide indexable cutting insert on drill of diameter 20mm. Cutting parameters such as cutting speed and feed rate were varied according to different cutting parameter level while wear in peripheral insert was inspected before and after each test run start. Machine rigidity in terms of vibration acceleration amplitude in x-, y-, and z-axis were measured and analyzed. Process capability index, Cpk of drilled hole accuracy was calculated. A regression model based on this experiment was established for predicting the process capability of machine tool in drilling operation. The established regression model is proven to have high accuracy, which is more than 80%. The validation test was carried out on a different machine tool with the same cutting conditions to check if different machine was adaptable to the regression model. This finding provides useful guidelines for machning operator to predict the process capability of the machine tool in the drilling process.