Papers by Keyword: Milling

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Authors: Nik Masmiati Nik Pa, Ahmed Aly Diaa Sarhan, Mohd Hamdi Abd Shukor, Mohsen Abdelnaeim Hassanim Mohamed
Abstract: Milling is a machining process by which a surface is generated by a progressive chip removal. An experimental investigation has been carried out on the performance of up and down milling under dry and flood conditions when end milling medium carbon steel utilizing titanium coated carbide tools. The performances are evaluated in terms of the cutting force, specific energy and power of cutting tool. The results show that milling in dry condition under up milling mode produce higher cutting force, specific energy and power. However, cutting under down milling mode gives less significant effect either being cut in dry or flood condition.
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Authors: F. Campo, Jairo A. Escobar Gutiérrez
Abstract: This work develops a mathematical model that explains the ball mills operational speed. The scope of the model is defined by the powder as the number of particles per cm3 and the Relevance defined as the ratio between different forces. In this study, the Relevance is defined as the ratio between superficial tension and inertial forces. The conditions for a free flowing powder and a single particle are differenced and non-dimensional numbers are found. The model proposed use the friction force between mill walls and the powder mass is related by a friction coefficient that can be calculated from angle repose. An experimental approach proves that the suppositions made in order to develop the model were adequate in this way the existence of the non-dimensional numbers is confirmed. It is also discussed the use of non-dimensional numbers to increase processing speeds with by increasing gravity clarifying that a given Relevancy, it is not dependent of the non-dimensional numbers. Thus, the model can help in the design process of ball mills with a deeper understanding of the phenomena.
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Authors: Jie Zhang, Abel Cherouat, Houman Borouchaki
Abstract: As a material removal process, metal milling process involves large geometry deformation, material thermo-visco-plastic flow coupled with damage and complex contact-friction problems. During simulation of metal milling, the finite elements distort severely at the local regions with high gradient of physical field such as stress, strain and temperature due to these problems. This paper presents numerical adaptive remeshing procedure dedicated to metal milling process. The procedure integrates Explicit solver of ABAQUS, OPTIFORM mesher and python script program transfer to execute step by step the incremental milling process. At each step, the meshes are refined and coarsened automatically based on geometrical and physical error estimations; the physical fields are transferred (point to point) from old to the new one using advanced algorithm. Johnson-cook material model is used to simulate the material plastic flow with ductile damage. Some numerical results are given to demonstrate the efficiency of the proposed procedure.
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Authors: Kwang Sun Kim, Choon Man Lee
Abstract: Silicon nitride ceramic has been used in various engineering applications such as bearings, rollers, and exhaust valves for automobiles because of its corrosion resistance, high-temperature strength and low density. LAM (Laser assisted machining) has recently been considered as an alternative and effective process for machining ceramic materials. The laser heat sources in laser assisted milling processes are irregularly varied according to shapes of workpieces. Therefore, prediction and analysis of preheating temperature is difficult. In this study, the thermal analysis and experiment were performed to evaluate the surface temperature distribution of silicon nitride according to laser power. In addition, the preheating temperature was predicted by analyzing the results of the thermal analysis.
287
Authors: Alex O’Connor, Mamidala Ramulu
Abstract: A mechanistic model capable of predicting end milling cutting forces in brittle porous media is described. A coefficient which is capable of reproducing the random shape and variation in cutting forces due to porosity is proposed. In addition, a method of experimental determination of cutting force coefficients is outlined. The proposed model is based on the hypothesis that the random shape and variation in cutting forces of brittle porous media coincide with the shape and variation of pore size and distribution in the media. The developed coefficient and model is compared to end milling tests conducted in CB1100, a porous machinable alumina based ceramic manufactured by UMECO. High correlation between predicted and measured cutting forces is shown. Experiments show that the model is capable of accurate prediction of variation in individual cutting tooth force profile shape and overall magnitude over the entire range of machining conditions tested. The benefit of the model lies in its ability to greatly reduce the number of cutting tests required when investigating cutting forces in novel brittle porous materials.
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Authors: Christian Effgen, Bejamin Kirsch
Abstract: In this paper, a new method for the preparation of cutting edges via grinding is presented. This method enables the manufacturing of the tool macro and micro geometry in one setup without reclamping, allowing improved flexibility, repeatability and accuracy at reduced processing times. This new method is path controlled using a special elastic bond for the grinding wheels. By using elastic bond, a rounded cutting edge instead of undesired chamfers can be achieved, as the bond nestles around the cutting edge and elastically deforms. The elastic bond is specified by the grain concentration and its basic hardness. Besides the specifications of the bond, the process kinematics highly influences the properties of the cutting edge. The kinematics is a combination of the tool path (machining strategy) and the grinding wheel geometry. The presented experiments include the examination of three different kinematics using three different grinding wheel geometries, FEPA 1A1, 1V1 and 4A2. For each kinematics, three different grain concentrations and three degrees of basic bond hardness were tested, resulting in a complete amount of 27 parameter combinations. The outer diameter cutting edges of cemented carbide milling tools (end mills) were prepared in a 5-axis tool grinding machine. The shape and quality of the achieved cutting edge rounding was qualitatively evaluated by means of scanning electron microscopy (SEM).
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Authors: Satoru Maegawa, Yuta Morikawa, Shinya Hayakawa, Fumihiro Itoigawa, Takashi Nakamura
Abstract: This paper presents a novel concept for extending the life of the tools that are used in the milling process of carbon-fiber-reinforced plastic (CFRP) composites. Three types of tools were compared in milling tests; tool I: an uncoated tungsten carbide (WC-Co) tool, tool II: a polycrystalline diamond (PCD) tool, and tool III: a combination tool comprising a PCD layer surface with a thickness of 100 μm and a WC-Co substrate flank surface. The measurement of changes in cutting forces over cutting distance revealed that tool III had a better (tool) life performance than the other tools. Additionally, observation of changes in the edge profiles of the tools revealed that the effective edge sharpness of tool III remains constant during the milling tests. The difference between the wear rates of the PCD rake and WC-Co flank surfaces in tool III maintained a constant effective sharpness during the milling process, and it extended the tool life. Based on our findings, we concluded that using the difference between the wear rates of rake and flank surfaces is an effective technique for tool life extension in the milling process of CFRP laminates.
198
Authors: Xue Qin Pan, Na Zhu, Yu Cai Dong, Cui Xiang Liu, Min Lin, Xiao Yan Wang
Abstract: A novel prediction model for surface roughness based on Projection Pursuit Regression was proposed in this paper. Based on the new model, the effects of milling parameters on surface roughness in milling can be predicted, and the predicted value of surface roughness in the whole working range can be reached with the limited test data, thus the variation law of quality of machined surface following milling parameters can be obtained. Compared with the least square support vector machine, it can be revealed that on the base of the same samples, the construction speed of this Projection Pursuit Regression is 1~2 higher in order of magnitude than that of the least square support vector machine, while the prediction errors are 40 % of the latter. Thus, the prediction model based on Projection Pursuit Regression can be established fast and be forecasted in high-precision, it is suitable for prediction of surface roughness.
143
Authors: Huai Zhong Li, Jun Wang
Abstract: nconel 718 is one of the most commercially important superalloys but with very poor machinability. It has a very high yield stress and a high tendency to adhesion and work-hardening. A recent trend of improving the machining processes of difficult-to-cut materials is to move towards dry cutting operations. This paper presents an experimental study of the cutting forces in high speed dry milling of Inconel 718 using a milling cutter with coated carbide inserts. It is found that the peak cutting forces increase with an increase in chip load in a nonlinear way, but cutting speed does not show a significant influence on the cutting force for the range of cutting speeds tested in this study.
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Authors: Chung Shin Chang
Abstract: The main purpose of this paper is to study the carbide tip's surface temperature and the cutting forces of milling stainless steel with nose radius worn tools. A new cutting temperatures model incorporating tool worn factor and using the variations of shear and friction plane areas occurring in tool worn situations are presented in this paper. The frictional forces and heat generation on elementary cutting tools are calculated by using the measured cutting forces and the oblique cutting analysis. The tool tip and cutting edges are treated as a series of elementary cutting tips. The carbide tip’s temperature distribution is solved by finite element analysis (FEM) method. Keywords: Milling, stainless steel, cutting temperatures, nose radius tools, FEM
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