Advanced Noncontact Cutting and Joining Technologies

Traditional cutting processes are becoming obsolete in many modern applications because of their limitations or prohibitive to use or as a non-viable option for such modern applications. Conventional cutting processes such as turning and milling have become non-economical cutting processes for most of the advanced engineering materials that are developed to be high performing due to the nature of applications they are intended for. Most of these materials interact with the cutting tool in such a way that the cutting tools are consumed more rapidly during the cutting process that increases the downtime and increases the cost of manufacturing or they can even destroy the material make-up, most especially advanced composite materials. Difficult-to-machine materials are costly to machine using these traditional machining processes. In view of the aforementioned problems, the need for advanced machining processes became imperative. Also, the machines and devices are now designed to become smaller than they used to be. The need to reduce global warming is another driving force for the development of advanced machining processes. The constant strive to make moving and flying machines such as automobile and aerospace smaller and more compact is one of the requirements to reduce global warming. There is need to have a cutting process that is able to machine materials with high accuracy and at micro- and nanoscale levels. Joining these advanced materials as well as joining of materials at micro- and nanoscale levels is inevitable because at one point or the other, materials are joined during fabrication processes. Conventional welding processes could not be used to join these advanced and micro- and nanoscale materials because of large heat-affected zone that is associated with this welding processes. Also, the tools used in most of these conventional welding processes are even larger than the workpiece. Contact-less machining and welding processes are desired to be able to efficiently and effectively machine and join these high-technological materials. The section A of this book deals extensively with the various advanced non-contact, and tool-less machining processes such as laser machining, water jet machining and chemical machining. Non-contact joining processes are dealt with in great detail in section B of this book which include laser welding, ultrasonic welding and explosive welding processes. In this chapter, a brief introduction of these advanced machining and joining processes is presented.

Chemical machining (CM) is an advanced machining technique that is used to selectively remove material from workpiece using strong chemical reagent known as etchant. The corrosion process is utilised to remove material from the needed area of the workpiece. The material removal in chemical machining process takes place by microscopic electrochemical reaction or chemical dissolution of the material to be removed. Chemical milling and photochemical milling processes are the two important chemical machining processes that are presented in this chapter. The mechanism of operation of these chemical machining processes is explained. Some of the research progress in these processes is also presented. The chapter ends with a brief summary.

Electrochemical machining process is an advanced cutting process that is based on Faraday law of electrolysis in which reverse electroplating process is used to achieve metal removal. It can be used to machine hard and difficult-to-machine materials. This important advanced machining process is described in this chapter. Development of new materials comes with lots of challenges in machining such materials because of the extreme properties of such materials that make it difficult to process these materials using the traditional manufacturing process. Electrochemical machining can be used to easily machine complex and intricate parts from these advanced materials and at mass production rate. Different types of electrochemical machining processes and processing parameters that influence the properties of material are presented. Advantages, disadvantages and areas of applications of electrochemical machining process are highlighted. Some of the research works in electrochemical machining process are also presented in this chapter.

Electrothermal cutting processes employ a combination of electrical energy and heat to achieve material removal process. Many materials will burn when subjected to heat. By bringing materials into melting and vaporisation state, material cutting can be achieved. Electrothermal machining is an advanced machining process which is contact-less and hence does not require the physical contact of the tool and the workpiece making cutting forces negligible. There are different types of electrothermal machining processes such as electrical discharged machining, electron beam machining and laser beam machining, which are explained in this chapter. This advanced machining process however uses thermal energy to achieve the desired cutting process but does not create heat damage to the material when compared to the similar conventional cutting processes. The principles of operation of each of these processes are explained in this chapter with their advantages, limitations and areas of application. Some research works in this field are also presented.

The need of advanced materials required in the modern-day technology and the demand of miniaturisation from different kinds of engineering applications have led to the development of cutting processes that are able to offset the limitations encountered in the conventional manufacturing processes. Advanced mechanical cutting processes such as waterjet machining, abrasive waterjet machining and ultrasonic machining are important advanced machining processes that are contactless and tool-less processes used to cut advanced materials and in micromachining where the conventional machining process becomes prohibitive. These advanced mechanical cutting processes are analysed in this chapter. The working principles of these cutting processes are described with the advantages, disadvantages and areas of application presented. Some of the research works in this field are also presented in this chapter.

In the last two decades, products have been revolutionised by making them smaller, lighter and even more compact. Some of the requirements for making products smaller and lighter were borne out of the necessity to reduce global warming through the reduction of fuel consumption in moving parts (transportation industries). Also, the bulkiness of products in the past was partly as a result of manufacturing limitations, that is, unavailability of suitable manufacturing process to fabricate the smaller product. Miniaturisation has gained popularity in every areas of human endeavour, ranging from laboratory instruments which were once gigantic and can now fit into one’s palm (becoming handheld). The push towards miniaturisation is constantly being pursued in the research community through the development of manufacturing technology that promotes miniaturisation pursuit as well as constant development of these technologies. Advanced cutting technologies take a significant role in achieving miniaturised components since manufacturing these micro- and nano-components relied heavily on effective cutting processes. In this chapter, micro- and nano-machining using various advanced cutting processes that were presented in Chaps. 2–5 in this book is presented. A number of research works have appeared in the literature on these interesting areas of research and some of them are presented in this chapter.

Non-contact joining technology is an advanced joining method in which there is no contact between the tool and the materials being joined. There are two basic types of welding process namely fusion- and solid-state welding. Laser beam welding and electron beam welding processes are the non-contact fusion-state welding processes that are discussed in this chapter. These non-contact welding techniques have found their applications in different spheres of our lives. Each of these welding techniques with their areas of application is discussed in this chapter. Some of the research works in this field are also presented. Most of these welding technologies are key in the development of miniaturised components. The application of these advanced welding technologies in micro- and nano-fabrication is the focus of Chap. 9.

Solid-state non-contact joining technology is an advanced joining method that does not involve melting of the workpiece and there is no direct contact between the tool and the workpiece. Ultrasonic welding, friction welding, explosive welding and resistance welding are the four non-contact solid-state welding techniques that are discussed in this chapter. The principle of operations, advantages, disadvantages and areas of applications of each of these advanced welding techniques are explained. Some of the research works in this area are also presented.

Micro- and nanoscale welding or joining processes are needed in miniaturisation or microsystem fabrication such as microelectromechanical systems (MEMS) and carbon nanotubes (CNTs). The constant strive for miniaturisation that necessitates that products are manufactured smaller and more lighter comes with the challenge of having smaller parts that require to be joined or assembled at a micro- or nanoscale level. The ability to weld at micro- and nanoscale levels is key to the efficient and effective fabrication of miniaturised components and products. This need has necessitated the development of welding processes that have the capability to join these delicate and fragile parts. The conventional joining process could cause heat damage to the welded part because of the large input from such processes. Also, the tools of these conventional welding processes may even be larger than the miniaturised parts that makes them unsuitable in fabrication of parts at micro- and nanoscale levels. Micro- and nanowelding are performed under powerful microscope. In this chapter, non-contact micro- and nanowelding processes are discussed. Two types of these advanced welding processes discussed are the advanced non-contact fusion welding and solid-state welding processes. Laser micro/nanowelding and electron beam micro/nanowelding are the two fusion-state micro/nanowelding processes that are presented in this chapter. For the solid-state micro/nanowelding processes, ultrasonic micro/nanowelding and resistant micro/nanowelding are presented. In micro- and nanowelding processes, the main challenge is the tight operational tolerance that needs to be met and the processing parameters are found to play an important role in achieving the desired results. The focus of this chapter is on the research developments in this field. The working principles, advantages, limitations and areas of application of these welding processes are explained in Chaps. 7 and 8.