Nontraditional Machining Processes

This chapter presents the basic principles, applications, and future prospects of various laser-assisted manufacturing techniques used for material removal, joining, and additive manufacturing. The laser hazard and safety aspect is also briefly included.

The cost of cutting hard-to-machine materials by conventional mechanical machining processes is high due to the low material removal rate and short tool life, and some materials are not possible to be cut by the conventional machining process at all. Laser beam machining is the machining processes involving a laser beam as a heat source. It is a thermal process used to remove materials without mechanical engagement with workpiece material where the workpiece is heated to melting or boiling point and removed by melt ejection, vaporization, or ablation mechanisms. In contrast with a conventional machine tool, the laser radiation does not experience wear, and material removal is not dependent on its hardness but on the optical properties of the laser and the optical and thermophysical properties of the material. This chapter summarizes the up-to-date progress of laser beam machining. It presents the basics and characteristics of industrial lasers and the state-of-the-art developments in laser beam machining.

In laser cutting process, thermal stress is formed around the cut edges, which becomes important for the geometries having the corners. In the present study, laser cutting of triangular shape in aluminum foam is carried out. Temperature and stress fields are predicted using a finite element method in line with experimental conditions. Metallurgical and morphological changes in the cut sections are examined incorporating scanning electron microscope (SEM) and energy-dispersive spectroscopy. It is found that the cut sections are free from defects such as sideways burning and large-scale burrs. von Mises stress is high in the corners of the triangular-shaped laser cut workpieces.

This chapter provides a comprehensive overview on the micro-electrical discharge machining (micro-EDM) process. The physical principle of micro-EDM and differences between macro- and micro-EDM and micro-EDM system components are discussed. A discussion on major operating parameters of micro-EDM and their effect on the performance parameters is presented. A brief discussion on variants of micro-EDM and their industrial applications has been included. The research advances on the areas of micro-EDM and micro-EDM-based compound and hybrid machining processes have been discussed. Finally, a comparative evaluation of micro-EDM to other machining processes has been presented.

This chapter presents constructive details for a micro-electrical discharge machine that is adequate to study the fundamentals of the process and to educate upcoming engineers in the latest industrial technologies. The machine was designed, fabricated, and instrumented by the authors and consists of a rigid structure, electrical and electronic components, a dielectric flowing system, and positioning control devices. The machine operates with low voltage, low energy, and high-frequency short electrical pulses and makes use of tool electrodes that are capable of drilling holes with diameters in the micrometer range. The presentation provides constructive details for those readers who may be interested in developing an in-house μEDM and puts emphasis on its adequacy for investigating the influence of operative parameters on electrical spark discharges, morphology of craters, and material removal mechanisms.

Abrasive water jet (AWJ) machining and abrasive water jet cutting (AWJC) are widely used, especially where very hard materials like titanium (Ti) alloys, high-strength steel, ceramics, etc. need to be machined or cut. In this chapter, an overview of the abrasive water jet milling (AWJM) process is presented. The essential challenge is at controlling the depth of cut (DoC) produced by varying the important AWJ machining process parameters. Experimental studies, process modeling and control based on FEM, artificial intelligence techniques and regression, and mechanisms of material removal are covered from the recent literature with the focus being on Titanium alloys. Experimental study and nonlinear regression–based process modeling of controlled depth AWJ milling of Grade 2 Ti alloy is also presented. Finally, various challenges including scope of future research in AWJM are highlighted.

Manufacturing complex surfaces for high responsibility rotary components is critical in several applications, such as blades for turbomachinery, forged crankpins, iron casting crankshafts, grooved features of long power shafts and others. Nowadays there is a trend toward the performance of all required operations in the same machine tool, following the so-called multitasking approach. Traditional machine tools kinematic has developed into a new concept of multitasking machine, and even other non traditional processes such as laser tempering, laser cladding, rolling or burnishing are performed in the same machine and workpiece setup. In this chapter a new approach for the production of blades is deeply explained. A hybrid process for blades manufacturing is performed in a multitasking machine, by successive application of three no usual processes: turn-milling for cylindrical part definition, turn-ball-milling for contouring free form surfaces and finally burnishing for improving both final roughness and fatigue endurance. The outcome of this new approach is the obtaintion of functional complex parts with high integrity, quality and shortened lead times.