Advanced Machining Processes Vk Jain Pdf Free
Lillia Iniguez
As machining processes become more advanced, so does the science behind them. This book emphasizes these scientific developments in addition to the more widely covered technological aspects, providing a full understanding of how machining has adapted to material constraints and moved beyond conventional methods in recent years.
Numerous processes have been developed to allow the use of increasingly tough, corrosion-resistant, and temperature-resistant materials in machining. The advanced machining processes covered in this book range from mechanical, thermoelectric, and electrochemical, including abrasive water jet machining, electric discharge machining and micromachining, ion beam machining, and hybrid processes. It also addresses the sustainability issues raised by these processes. The underlying science of machining is centered throughout, as none of these processes can reach their full potential without both technical expertise and scientific understanding.
Generally, unconventional or advanced machining processes (AMPs) are used only when no other traditional machining process can meet the necessary requirements efficiently and economically because use of most of AMPs incurs relatively higher initial investment, maintenance, operating, and tooling costs. Therefore, optimum choice of the process parameters is essential for the economic, efficient, and effective utilization of these processes. Process parameters of AMPs are generally selected either based on the experience, and expertise of the operator or from the propriety machining handbooks. In most of the cases, selected parameters are conservative and far from the optimum. This hinders optimum utilization of the process capabilities. Selecting optimum values of process parameters without optimization requires elaborate experimentation which is costly, time consuming, and tedious. Process parameters optimization of AMPs is essential for exploiting their potentials and capabilities to the fullest extent economically. This paper describes optimization of process parameters of four mechanical type AMPs namely ultrasonic machining (USM), abrasive jet machining (AJM), water jet machining (WJM), and abrasive-water jet machining (AWJM) processes using genetic algorithms giving the details of formulation of optimization models, solution methodology used, and optimization results.
Advanced engineering materials such as polymers, ceramics, composites, and superalloys play an ever increasing important role in modern manufacturing industries, especially, in aircraft, automobile, cutting tools, die and mold making industries [1]. Higher costs associated with the machining of these materials, and the damage caused during their machining are major impediments in the processing and hence limited applications. Further, stringent design requirements also pose major challenges to their manufacturing industries. These include precise machining of complex and complicated shapes and/or sizes (i.e. an aerofoil section of a turbine blade, complex cavities in dies and molds, etc.), various hole-drilling requirements (i.e. non-circular, small or micro size holes, holes at shallow entry angles, very deep holes, and burr less curved holes), machining of low rigidity structures, machining at micro or nano levels with tight tolerances, machining of inaccessible areas, machining of honeycomb structured materials, fabrication of micro-electro mechanical systems (MEMS), and nano-finish and surface integrity requirements. Unconventional or advanced machining processes (AMPs) have been developed since the World War II largely in response to new, challenging, and unusual machining and or shaping requirements [2]. Alting [3] classified the AMPs into four categories according to the type of energy used in material removal: chemical, electro-chemical, mechanical and thermal.
Generally AMPs are characterized by low value of material removal rate (MRR) and high specific energy consumption. AMPs are used only when no other traditional machining process can meet the necessary requirements efficiently and economically because most of the AMPs are associated with relatively higher initial investment cost, power consumption and operating cost, tooling and fixture cost, and maintenance cost. Therefore effective, efficient, and economic utilization of capabilities of AMPs necessitates selection of optimum process parameters. Generally, values of process parameters of AMPs are selected either based on the experience, expertise, and knowledge of the operator or from the propriety machining handbooks. Selection of process parameters based on the operator experience does not completely satisfy the requirements of high efficiency and good quality. While machining tables can be a better choice in a factory environment for one or two processes but cannot be used for a wide range of machining processes and their operating conditions. In most of the cases, selected parameters are conservative and far from the optimum. This hinders optimum utilization of the process capabilities. Selecting optimum values of process parameters without optimization requires elaborate experimentation which is costly, time consuming, and tedious. Therefore, to exploit potentials and capabilities of AMPs to the fullest extent economically, their process parameters optimization is essential.
In mechanical type AMPs, material is removed by mechanical means like abrasion, erosion, or shear depending on the nature of workpiece material, and machining conditions. Of the six main mechanical type AMPs, abrasive jet machining (AJM) and ultrasonic machining (USM) can be considered as material removal processes particularly suitable for hard and/or brittle materials. Water jet machining (WJM) and abrasive-water jet machining (AWJM) are generally used for cutting and cleaning purposes. While, abrasive flow machining (AFM) and magnetic abrasive finishing (MAF) are fine finishing processes. This paper describes details of process parameters optimization of four mechanical type AMPs namely, USM, AJM, WJM, and AWJM processes using genetic algorithms (GA).
While making a part from raw material, one may require bulk removal of material, forming cavities/holes and finally finishing as per the parts requirements. Many advanced finishing processes have been employed to make circular and/or non-circular cavities and holes in difficult-to-machine materials. Some of the processes employed for hole making are electro-discharge machining, laser beam machining, electron beam machining, shaped tube electro-chemical machining and electro-chemical spark machining. With the demand for stringent technological and functional requirements of the parts from the micro- to nanometre range, ultra-precision finishing processes have evolved to meet the needs of the manufacturing scientists and engineers. The traditional finishing processes of this category have various limitations, for example, complex shapes, miniature sizes, and three-dimensional (3D) parts cannot be processed/finished economically and rapidly by traditional machining/finishing processes. This led to the development of advanced finishing techniques, namely abrasive flow machining, magnetic abrasive finishing, magnetic float polishing, magneto-rheological abrasive finishing and ion beam machining. In all these processes, except ion beam machining, abrasion of the workpiece takes place in a controlled fashion such that the depth of penetration in the workpiece is a small fraction of a micrometre so that the final finish approaches the nano range. The working principles and the applications of some of these processes are discussed in this chapter.
Mechanical erosion-based drillings are abrasive water jet drilling (AWJD) and ultrasonic drilling (USD). In these processes, materials are removed by the mechanical erosion of work material by high-pressure slurry (abrasive particles mixed with water). AWJD can produce miniature-sized holes on metallic and non-metallic materials. USD is used for machining miniature-sized holes on conductive and non-conductive materials having a hardness of more than 40 HRC. In thermoelectric erosion drilling methods, thermal energy is utilized to remove materials by melting and vaporization. These methods include ram-based spark-erosion machining (SEM), spark-erosion drilling (SED), and laser drilling. SEM and SED are used to produce miniature-sized holes on electrically conductive materials irrespective of their hardness, while laser drilling is used to produce miniature-sized holes on non-reflective metallic materials. The material removal rate in laser drilling is higher than in SED and SEM processes. The micro versions of SEM and SED are micro-spark-erosion machining (µ-SEM) and micro-spark-erosion drilling (µ-SED). Electrochemical drilling (ECD) is used to produce microholes on workpieces by ion displacement. It involves anodic dissolution where an electrolytic cell is formed by a tool (cathode) and workpiece (anode) surrounded by the continuous flowing electrolyte. In chemical drilling (CHD) methods, miniature-sized holes are produced by the chemical action of the corrosive agents.
Advanced Gear Manufacturing and Finishing offers detailed coverage of advanced manufacturing technologies used in the production of gears, including new methods such as spark erosion machining, abrasive water jet machining, additive layer manufacturing, laser shaping, and sustainable manufacturing of gears.
Abstract:The increased demand for miniature components has drawn the attention of researchers, engineers, and industry users to manufacture precision micro and mesoholes on foils, sheets, and plates made from a variety of engineering materials. These days, micro-drilling is extensively being adopted as a fundamental operation in all kinds of smart manufacturing industries to make different types of microholes, such as through holes, blind holes, and taper holes on micro-parts and components. Drilled holes with a diameter of less than 1 mm are referred to as microholes, while drilled holes whose diameter ranges between 1 and 10 mm are known as mesoholes. Meso and microholes are commonly referred to as fine-holes. Modern or advanced drilling processes are mostly used to drill microholes from a variety of materials. This paper presents an extensive review of the previous research conducted on the drilling of fine holes (meso and micro size) by spark- erosion-based processes along with highlighting work and tool electrode materials, specifications of drilled holes, types of microholes (through or blind holes), process parameters, performance measures, and key findings. The paper aims to facilitate researchers and scholars by highlighting the capabilities of spark erosion machining, drilling, and its variants to fabricate miniature holes. The paper ends with a conclusion and future research directions to encourage further work in this area.Keywords: electrode wear; material removal rate; microhole; spark erosion drilling
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