Papers by Keyword: Machining

Abstract: This paper describes approaches developed for the using of indentation method for evaluating the effectiveness of traditional and innovative kinds of ceramic parts manufacturing. Experimental studies revealed relationship between conditions of the grinding and pulse laser machining with the number and length of cracks, as well as local fracture area during indentation. Essential impact of regimes of these technological processes on the nature of cracks and local fracture formation during indentation of oxide-carbide ceramic surface was disclosed. The analysis of effectiveness of different methods of forming the surface of ceramic parts using the revealed effects was done.

Abstract: In this article we perform comparative analysis of the criteria of fracture during blade machining simulation, characterized by high intensity of the strain rate (about 10^-6 s^-1). For each 3D virtual experiment a milling processing model has been developed in DEFORM software package. The character of chip segmentation during the simulation was determined the accepted failure criterion. The adequacy of the model was evaluated by full-scale experiment based on geometry of real chips.

Abstract: This paper describes the development of a direct drive motor (DD motor) without a reduction gear for the rotary motion of machine tools and its performance. We investigate novel DD motors from a view of total performance on machine tools. Moreover, we estimate to employ the developed DD motors for 5-axis control machine tools and the multi-functional machine tools. The study proves the required performance of rotary motion is achieved on machine tools, and the developed DD motors are found to be effective as follows. First, designing a DD motor with quality engineering and FEM analysis of electro-magnetic field is found to be effective for a low cogging torque and a low torque ripple. It is demonstrated that the developed DD motor makes it feasible to generate the excellent surface roughness on the complex shape workpiece with a ball-nose endmill tool, compared with the machined surface roughness by a conventional rotary axis with a reduction gear. Second, a maximum angular velocity of the DD motor is balanced with a maximum velocity of the linear axis, but a maximum angular acceleration of the DD motor is not balanced enough with a maximum acceleration of the linear axis. Therefore, the angular acceleration is needed to be improved as a next step.

Abstract: The design and application of hard and superhard (H ≥ 40 GPa) coatings and their properties are discussed with the focus on superhard nanocomposites. The main part of the article deals with examples of industrial applications of hard and superhard nanocomposite coatings as wear protection coatings on tools for machining, forming, stamping, injection molding and the like. The advantages and possibilities as well as the limitations of the different types of coatings with emphasis on the nanocomposites are discussed and illustrated by a number of examples from aerospace and other branches of industry.

Abstract: A turning knife contacts a work piece during turning. Due to friction, heat is produced proportionally to the turning speed. The resulting temperature influences the quality of the machined surface and wear of the knife. Thus, new machine tools must be developed that minimize the production of unwanted heat. To accomplish this task, a new experimental knife was prepared with thermocouples both built into it and welded to its surface. The measurement process was supplemented by thermovision. Heat flux and surface temperatures were computed from subsurface data using a one-dimensional inverse relationship. The detailed temperature distribution on the surface of the turning knife was determined using a combination of these methods.

Abstract: Machining of fibre-reinforced thermosets is becoming a very popular technology today. Nevertheless, machinability of these materials is rather different from conventional materials such as metals since hard and abrasive fibres are combined with relatively soft resin with low glass transition temperature. Special attention has to be given to workpiece quality because delamination and burning of machined surface can occur. An experimental investigation into machinability of a polymeric and cellulose fibre-reinforced resin material was carried out. Milling operations were inspected with respect to process temperature, cutting forces and machined surface quality. The effect of cutting conditions on the mentioned aspects was determined. Standard and tailored cutting tools were used in the investigation. It was observed that surface quality is strongly dependent on tool geometry, milling strategy, fibre orientation and feed. On the other hand, cutting forces are relatively low and dependent on tool geometry and feed. The modified cutting tool with more positive tool geometry showed better results compared to the conventional one.

Abstract: This paper describes an overview of Fuzzy Logic (FL) application for solving machining problems. The developed fuzzy prediction model is an essential operational guideline for machinist in decision making and adjusting process parameters. This paper also discussed the previous literature that applied the FL in modeling machining process.

Abstract: The successful optimization process of machining parameters is significantly important to the green manufacturing industries. However, the optimization process of machining problem is difficult to solve using conventional optimization techniques. Hence, the computational approach methodology such as Harmony Search (HS) is considered as an alternative way for optimization process in manufacturing industries. This paper discusses the overview of Harmony Search (HS) to optimize the machining parameters in machining process. Example of previous works that applied HS algorithm in machining optimization problems are also discussed.

Abstract: This paper provides an inclusive review of literature, mostly from the past decade, on optimization techniques of composite materials machining, both conventional and non-conventional process. Composite materials are continually replacing conventional materials due to their excellent corrosion resistance, higher strength to weight ratio, but the machining of composites is a challenging process. Experimental trials notwithstanding, researchers have also used various optimization techniques such as Taguchi method, Genetic Algorithm, Simulated Algorithm, Response Surface Method, and Fuzzy Logic with ANOVA etc., to identify the optimal parameters for the machining processes. Also predictive modeling techniques such as Artificial Neural Networks and Finite Element Methods have also been employed as an optimization tools for studying the composite machining process. It was found that Taguchi method is the most preferred technique in the optimization studies.

Abstract: The implementation of the Differential Evolutionary Algorithm for the solution of a multi-pass turning optimization problem is presented in this paper. The optimization of a multi-pass turning process is a highly demanding problem due to the number of constraints imposed. A specific variation of the Differential Evolutionary Algorithm appropriate for the treatment of constrained problems is used. It is based on the separation of candidate solutions into those that satisfy all constraints and those that do not and the simultaneous execution of two optimization algorithms. Numerical results from the minimization of the production cost of a popular multi-pass turning problem with six degrees of freedom, namely cutting speed, feed rate and depth of cut of rough machining and finishing, validate the methodology. The selected problem is characterized by a number of equally stepped roughing passes and a final finishing pass of the cutting tool in order to obtain the desired metal part removal from the initial workpiece.