Tehno-ekonomska analiza obrade abrazivnim vodenim mlazom i elektroerozijske obrade žicom

Nowadays, carefully selected technologies for material machining can significantly affect quality of machined surface and the cost of machining. Stainless steels are increasingly used in modern production. Austenitic stainless steels (type AISI 304 including Č 4580) make up over 50% of total world production of stainless steel. Nowadays, several methods for machining of these materials are available in practice. However, some types of machining cause the change in the material properties. Machined surface quality in the function of traverse speed and costs of the stated machining methods has been selected for comparative analysis of the machining methods. This paper presents an analysis of steel machining technology (4580 type of steel) with two different machining methods - abrasive water-jet and wire electrical- discharge machining. In addition, an economic analysis of the two machining methods has been conducted from the cost standpoint.Nerđajući čelici su danas sve više koriste u savremenoj proizvodnji. Od ukupne svetske proizvodnje nerđajućih čelika, čak 50% čine austenitni nerđajući čelici iz grupe AISI 304, u koju spada i čelik Č 4580. Danas je u praksi dostupno nekoliko metoda za obradu ovih materijala. Međutim, kod nekih vrsta obrade dolazi do promene karakteristika ovih materijala. U ovom radu je vršena obrada čelika Č 4580 sa dva različita postupka obrade – abrazivnim vodenim mlazom i elektroerozionom obradom sa žicom. Za uporednu analizu postupaka obrade izabran je kvalitet obrađene površine u funkciji brzine rezanja i troškovi navedenih postupaka obrade

Proposition of a solution for the setting of the abrasive waterjet cutting technology

The submitted paper aims to clarify the abrasive waterjet technology, particularly from the point of view of produced surface topography. It provides a new insight into the deformation process caused by the effect of abrasive waterjet and into the possibilities of using the surface topography for solving the issues of optimization of the process. The subject of study is a system of cutting tool, material and final surface topography and optimization of their parameters. The cutting or disintegrating tool of abrasive waterjet technology is flexible. The trajectory of its cut traces is strictly determined here by disintegration resistance at critical moments of tool-material interaction. The physico-mechanical character of the interaction within the cut will manifest itself in the final surface condition. This process can be re-analysed by measuring the selected elements of topography and roughness on the final surface, namely depending on the depth of the cut, technological parameters of the tool and mechanical parameters of the material. The mentioned principle is the basis of the presented solution. It lies in the analytical processing and description of correlation interrelations between set technological and measured topographical quantities in relation to the depth of cut and the type of material.Web of Science13528527

Airborne acoustic emission of an abrasive waterjet cutting system as means for monitoring the jet cutting capability

Abrasive waterjet cutting is a manufacturing technology making use of a high-speed waterjet with abrasive particles in suspension, for cutting materials with different mechanical properties. Product quality requirements are pushing towards an improvement of tracking and stabilization methods of the relevant process variables. Amongst those, the jet kinetic power defines the cutting capability and has a significant impact on the final cut features. This variable is subject to relevant fluctuations versus time. Besides, the current state of the art does not provide means for its in-line monitoring. The aim of this contribution is to monitor the airborne acoustic emission of an abrasive waterjet cutting head and investigate its correlation with the jet kinetic power. The investigation is carried out by means of factorial studies, in which the jet is fired at various water pressures and abrasive feed rates, providing different kinetic powers. The acoustic emission is synchronously monitored by means of a condenser microphone, installed on the cutting head. Data at frequencies above 40 kHz is found to constitute a robust and selective acoustic signature of the airborne jet. The acoustic signature is proven to be an effective in-line indicator of the jet kinetic power and its pressure-induced variations, whilst abrasive-induced variations remain undetected. A calibration procedure is presented, for translating the acoustic data into a jet kinetic power. The method is validated by means of further experiments that envisage its deployment in a real scenario. Overall, the presented method constitutes a robust tool for monitoring pressure-induced variations of the jet cutting capability

Development of icejet-based surface processing technology

The objective of the proposed work is to acquire knowledge needed for the development and deployment of manufacturing processes utilizing the enormous technological potential of water ice. Material removal by blasting with ice media such as particles, pellets and slugs was investigated. The ice media was accelerated by entrainment in a fluid stream (air, steam, liquid water, supercritical C02), impact of rotating blades, fluid expansion, etc. The ice-airjet has to replace sand blasting and the ice-waterjet has to replace the abrasive waterjet. Based on these results, technical approaches for surface processing and machining will be improved. A primary advantage of the ice media is movement toward more complete pollution prevention. With this technique, it is possible to eliminate both contamination of the substrate and generation of contaminated waste streams. In addition to the obvious environmental benefits, use of ice media has improved a number of key operational techniques, such as cleaning, decoating, polishing, deburring, drilling, cutting, etc. Production of ice media just-in-time at minimal environmental cost constitutes another advantage of ice-based technologies. A key objective of this research is to improve ice blasting so that it is not just feasible, but also technologically and economically efficient. An understanding of process physics and its application to the manufacturing operations are necessary in order to attain this objective. The feasibility and effectiveness of other than blasting ice-based technologies, such as precision temperature control, mixing, forming, etc. was also investigated. The principal issue in the use of the ice abrasives is formation of the ice particles. Two technologies of the particles formation were investigated. One of these technologies involves crushing and subsequent grinding of ice blocks. It is applicable at conditions when ice is readily available, for example at Arctic. Another process involved integration of water freezing and decomposition of the generated ice. It was shown that the size distribution of the particles is determined by the rate of the water supply and cooling conditions. The results of the experiments were used to suggest a technology for surface processing using ice powder. A process for formation of the powder of brittle materials was also discussed

Development of prediction technique for the geometry of the abrasive waterjet generated kerf

This study is concerned with the development of a practical and accurate technique for off-line determination of the variables characterizing the macro-geometry of the kerf generated in the course of abrasive waterjet (AWJ) machining of ductile materials. The study involved generation and processing of a database relating operational conditions with kerf dimensions. The total number of generated samples exceeded 1500. A physical model relating the process results with operational conditions was constructed and used for the selection of a statistical technique for analysis of the acquired experimental information. The semiempirical model developed here is based on a simple theoretical model which assumes that the particle distribution within the AWJ is statistically uniform. The good correlation found between the experimental results and the semiempirical model demonstrate the validity of this assumption. Regression equations, determining the depth of jet penetration, kerf width and taper, were constructed. The correlation coefficients between predicted and measured values of the kerf characteristics exceed 0.94. Only in one case out of 20 was the correlation coefficient 0.9. The observed result demonstrates the geometry of the kerf is controlled by the diameter of the jet and kinetic energy of particles. A practical, reliable procedure for construction of a prediction technique for AWJ machining of a material in question was suggested and tested. The proposed technique will be used for control of AWJ machining as well as for the development of an expert system

Understanding the Mechanism of Abrasive-Based Finishing Processes Using Mathematical Modeling and Numerical Simulation

Recent advances in technology and refinement of available computational resources paved the way for the extensive use of computers to model and simulate complex real-world problems difficult to solve analytically. The appeal of simulations lies in the ability to predict the significance of a change to the system under study. The simulated results can be of great benefit in predicting various behaviors, such as the wind pattern in a particular region, the ability of a material to withstand a dynamic load, or even the behavior of a workpiece under a particular type of machining. This paper deals with the mathematical modeling and simulation techniques used in abrasive-based machining processes such as abrasive flow machining (AFM), magnetic-based finishing processes, i.e., magnetic abrasive finishing (MAF) process, magnetorheological finishing (MRF) process, and ball-end type magnetorheological finishing process (BEMRF). The paper also aims to highlight the advances and obstacles associated with these techniques and their applications in flow machining. This study contributes the better understanding by examining the available modeling and simulation techniques such as Molecular Dynamic Simulation (MDS), Computational Fluid Dynamics (CFD), Finite Element Method (FEM), Discrete Element Method (DEM), Multivariable Regression Analysis (MVRA), Artificial Neural Network (ANN), Response Surface Analysis (RSA), Stochastic Modeling and Simulation by Data Dependent System (DDS). Among these methods, CFD and FEM can be performed with the available commercial software, while DEM and MDS performed using the computer programming-based platform, i.e., "LAMMPS Molecular Dynamics Simulator," or C, C++, or Python programming, and these methods seem more promising techniques for modeling and simulation of loose abrasive-based machining processes. The other four methods (MVRA, ANN, RSA, and DDS) are experimental and based on statistical approaches that can be used for mathematical modeling of loose abrasive-based machining processes. Additionally, it suggests areas for further investigation and offers a priceless bibliography of earlier studies on the modeling and simulation techniques for abrasive-based machining processes. Researchers studying mathematical modeling of various micro- and nanofinishing techniques for different applications may find this review article to be of great help

Multidisciplinary structural design and optimization for performance, cost, and flexibility

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.Includes bibliographical references (p. 155-165).Reducing cost and improving performance are two key factors in structural design. In the aerospace and automotive industries, this is particularly true with respect to design criteria such as strength, stiffness, mass, fatigue resistance, manufacturing cost, and maintenance cost. This design philosophy of reducing cost and improving performance applies to structural components as well as complex structural systems. Design for flexibility is one method of reducing costs and improving performance in these systems. This design methodology allows systems to be modified to respond to changes in desired functionality. A useful tool for this design practice is multi-disciplinary design optimization (MDO). This thesis develops and exercises an MDO framework for exploration of design spaces for structural components, subsystems, and complex systems considering cost, performance, and flexibility. The structural design trade off of sacrificing strength, mass efficiency, manufacturing cost, and other "classical" optimization criteria at the component level for desirable properties such as reconfigurability at higher levels of the structural system hierarchy is explored in three ways in this thesis. First, structural shape optimization is performed at the component level considering structural performance and manufacturing cost. Second, topology optimization is performed for a reconfigurable system of structural elements. Finally, structural design to reduce cost and increase performance is performed for a complex system of structural components. A new concept for modular, reconfigurable spacecraft design is introduced and a design application is presented.by William David Nadir.S.M

Remanufacturing and Advanced Machining Processes for New Materials and Components

"Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems.

Remanufacturing and Advanced Machining Processes for New Materials and Components

Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems