Papers by Keyword: Metal Cutting

Abstract: The present study describes the impact of various protective process agents on chip forming processes. The research was conducted on NiCr20TiAl and 34NiCrMoV14-5 nickel-chromium alloys. New lubricant-cooling process agents with carbon nanopowder additives are studied. The optimal composition of the nanopowder additive and its effect during alloy cutting is examined. Experiments reveal the dependence of shrinkage ratio on cutting speed and various protective process agents. The values of H50 microhardness are also defined when cutting these alloys using protective process agents. Experimental studies found the positive effect of developed agents with nanopowder additives on the processes of NiCr20TiAl and 34NiCrMoV14-5 alloys chip formation.

Abstract: The present study describes the impact of cutting speed and various lubricant-cooling process agents on the temperature of alloy turning. The research was conducted for NiCr20TiAl and N07750 nickel alloys with the help of HG30 and HS123 carbide-tipped cutting tools. New lubricant-cooling process agents with nanodispersed diamond graphite additives are studied. The optimal composition of the diamond graphite additives is revealed when cutting these alloys. It is demonstrated on the basis of tests the positive effect of diamond graphite agents on the quantitative changes in measured cutting temperatures. In doing so, the cutting speed and the lubricant-cooling agents applied to the cutting zone have little impact on the nature of temperature patterns.

Abstract: The adaptive control of metal cutting processes is a logical extension of the CNC systems. In CNC systems of metal-cutting processes the machining variables (e.g., the cutting speed and feedrate) are prescribed by the part programmer. The determination of these variables depends on experience and knowledge regarding the workpiece and tool materials, coolant conditions, and other factors.The determination of these operating parameters depends on experience and knowledgeregarding the workpiece and tool materials, coolant conditions, and other factors. By contrast,the main idea in adaptive control is the improvement of the production rate, or the reductionof machining costs, by calculation and setting of the optimal operating parameters duringmachining itself. This calculation is based upon measurements of process variables in real time and is followed by a subsequent on-line adjustment of the machining variables subject to constraints with the objective to optimize the performance of the overall system.The adaptive control is basically a feedback system, in which the operatingparameters automatically adapt themselves to actual condition of the process. AC system formachine tools can be classified into two categories:1.Adaptive control with optimization(ACO);2.Adaptive control with constraints(ACC);ACO refers to systems in which a given performance index (usually an economicfunction) is extremized subject to process and system constraints. With ACC, the machiningparameters are maximized within a prescribed region bounded by process and systemconstraints, such as maximum torque or power. ACC systems, however, do not use aperformance index. In both systems an adaptation strategy is used to vary the operatingparameters in real time cutting progresses. Although there has been considerable research onthe development of ACO systems, few, if any, of these systems are used in practice. The major problems with such systems have been difficulties in defining realistic indexes of performance and the lack of suitable sensors which can reliably measure on-line thenecessary parameters in a production environment. The objective of most AC systems isimprovement in productivity, which is achieved by increasing the metal removal rate (MRR)during rough cutting operations. The increases in productivity range from approximately 20 to 80 percent and clearly depend on the material being machined and the complexity of the part tobe produced.

Abstract: A multi-response optimization is a popular tool in many economic, managerial, constructional, manufacturing, process design, product design technologies, machinery and system, devices, process parameters etc. This research paper demonstrates the application of a simple multi-objective optimization on the basis of ratio analysis (MOORA) method to solve the multi-criteria (objective) optimization problem in the machining process. In this paper, the chip-tool interface temperature, main cutting force, and tool wear rate were investigated in various machining conditions in turning operations. Various machining parameters, such as the cutting speed, feed rate, and depth of cut and effective tool inserts nose radius, were considered. Composite factorial design (2⁴+8) was used for experimentation. Multiple response values were obtained using actual experimentation. By using these experiments, two different methods were proposed. Machining parameters were optimized by minimizing chip-tool interface temperatures, tool wear rate, and main cutting force during machining of alloy steel. The results obtained using the MOORA method almost agree with the grey relational analysis method which shows the authenticate applicability, potentiality, and flexibility of MOORA method for solving various complex decision-making problems in present-day manufacturing industries.

Abstract: In metal cutting, a severe thermo-mechanical load collective determines the friction and wear behavior at the tool-chip interface. The inaccessibility of this interface complicates studies and thus the understanding of tribological effects in metal cutting. During a tool’s lifetime, local friction conditions change drastically as coatings and tool geometry wear down. This paper shall provide a comprehensive overview of current methods to understand and describe friction conditions in metal cutting and how cutting induced surface layer states may influence the friction and wear behavior of the finished workpiece.

Abstract: From the invention of turning machine or lathe, some engineers are trying to increase the turning productivity. The increase of productivity is following after the breakout in instrumental area, such as the hard alloy instrument and resistance to wear cutting surfaces. The potential of cutting speed has a certain limit. New steel marks and cutting surfaces types allow significantly increase cutting and turning speeds. For the most operation types the productivity increase begins from the feeding increase. But the increase of feeding goes together with machined surface result decreasement. Metal cutting with high feeding is one of the most actual problems in the increasing of manufacturing volume but there are some problems one of them is the cutting forces increasement and larger metal removal rate, which decrease the cutting tool life significantly. Increasing of manufacturing volume, going together with the cutting instrument technology and material evolution, such as the invention of the carbide cutting materials and wear resistant coatings such as TiC and Ti(C,N). Each of these coating have its own properties and functions in the metal cutting process. Together with this evolution the cutting tool geometry and machining parameters dependencies are researched. Traditionally for the decreasing the machining time of one part, the cutting parameters were increased, decreasing by this way the machining operation quantity. In our days the wear resistance of the cutting tools increasing and it is mostly used one or two machining operations (medium and fine finishing). The purpose of the topic is to represent the experimental results of the stainless steel turning process, using increased cutting speeds and feeding values, to develop advanced processing technology, using new modern coated cutting tools by CVD and PVD methods. After investigation of the machined surface roughness results, develop the mathematical model of the cutting process using higher values of the cutting parameters.

Abstract: The paper considers the intensity degree of a plastic shear deformation e_i when cutting, the results of experimental studies that determine a travel trajectory of a cutting material layer through a plastic deformation zone in a chipping area and comparative analysis of deformation conditions of a sample material machined by various tool rake angles (γ=0o and γ=15o).

Abstract: The paper considers the issue of optimum design of active part of metalcutting tools. Active parts are made of composite full-strength tool materials degrading uniformly. High-quality tools can be manufactured provided that the issue is sold.

Abstract: Cutting process is a typical non-linear deformation problem, which involves material non-linear, geometry non-linear and the state non-linear problem. Based on the elastic-plastic material deformation theory, this theme established a strain hardening model. Build the simulation model of two-dimensional orthogonal cutting process of workpiece and tool by the finite element method (FEM), and simulate the changes of cutting force and the process of chip formation in the machining process, and analyzed the cutting force, the situation of chip deformation. The method is more efficient and effective than the traditional one, and provides a new way for metal cutting theory, research of material cutting performance and cutting tool product development.

Abstract: As the development of new materials and high speed machining, cutting fluid becomes more and more important because of its functions of cooling, lubrication, corrosion protection and cleaning. The main purposes of cutting fluid are decreasing temperature, reducing friction, extending tool life and improving machining efficiency. In precision machining, high machined surface integrity is the most important. In this paper, a preliminary experimental study on effect of two different cutting fluids on milled surface quality of iron-base superalloy was taken. The surface morphology, roughness, micro hardness and residual stress of the machined surface were investigated. The results showed that the material properties and geometric characteristics of the machined surface were significantly affected by cutting fluid conditions. The effect of cutting fluid on machined surface quality and service performance will become an important research direction. This paper also suggests the main contents of the further research on effect of cutting fluids on machined surface.