Advanced Noncontact Cutting and Joining Technologies: Micro- and Nano-manufacturing

By Rasheedat Modupe Mahamood and Esther Titilayo Akinlabi

This book illuminates advanced cutting and joining processes, what they are used for, and the capabilities of these manufacturing techniques, especially in micro- and nano-fabrication. The authors illustrate the use of water jets and lasers that can be used to cut highly complex shapes without leaving burrs of heat affected zones, as well as friction stir welding processes that were not possible in the past. Rounding out their examination, the authors describe in detail the use of additive manufacturing for fabrication of micro and nano-scale components and the direction of future research. Incorporating many examples from industry, the book is ideal for professional engineers, technicians, and fabrication managers in multiple industries.

• Maximizes understanding of advanced manufacturing processes and their capabilities, as well as the limitations of each of these technologies;
  
• Explains use of contactless manufacturing processes in applications such as electronics and sensor fabrication;
  
• Serves as a ready reference on the latest cutting and joining technologies, including those at the micro- and nano-scale.

• Language: English
• Publisher: Springer
• Release date: Mar 2, 2018
• ISBN: 9783319751184

Book preview

Part IAdvanced Noncontact Cutting Processes

© Springer International Publishing AG 2018

Rasheedat Modupe  Mahamood and Esther Titilayo  AkinlabiAdvanced Noncontact Cutting and Joining TechnologiesMechanical Engineering Serieshttps://doi.org/10.1007/978-3-319-75118-4_1

1. Introduction to Advanced Cutting and Joining Processes

Rasheedat Modupe Mahamood¹, ²   and Esther Titilayo Akinlabi¹

(1)

Department of Mechanical Engineering Science, Faculty of Engineering and the Built Environment, University of Johannesburg, Auckland Park Kingsway Campus, Auckland Park, Johannesburg, South Africa

(2)

Department of Mechanical Engineering, Faculty of Engineering, University of Ilorin, Ilorin, Nigeria

Rasheedat Modupe Mahamood

Keywords

Chemical machiningElectrochemical machiningElectrothermal machiningLaser weldingMechanical machiningUltrasonic welding

1.1 Introduction

Advanced, non-contact cutting and joining processes are relatively new fabrication processes that are borne out of necessities which include the need for sophisticated technologies such as high-technology phones and high-technology (high-tech) electrical and electronic devices that required materials to be cut and also joined together with high accuracy and excellent surface properties [1–3]. Also some parts in these high-tech gadgets are made of micro-sized components, hence the need for advanced cutting and joining processes. The product of other manufacturing processes may also need some finishing in the form of material removal such as trimming or grinding operations to be performed. Intricacies of some parts may make it difficult to remove extra materials from such parts using the traditional machining processes . The advanced non-contact machining processes are useful for such finishing operations. Advanced materials are developed to be harder, tougher and stronger materials because of the demanding application they are developed to serve. Machining or welding such materials poses a number of challenges when using the traditional machining and welding processes. Also, the manufacturing requirement of some new machines and equipment comes with high demand of excellent surface integrity and most of these parts are miniaturised with low tolerance and high precision requirement, making it difficult to achieve with the traditional machining and joining process. These challenges lead to the development of a number of new material removal processes and advanced joining processes. These new material removal processes are known as advanced machining method [2]. These advanced machining and joining processes are tool-less processes and are also contact-less process. This means that there is no physical contact between the machine and the workpiece and hence there is no interaction between the workpiece and the machining or welding equipment. Energies are used in their direct forms for the material removal and material joining purposes. An overview of some of these advanced machining and joining processes is presented in this chapter.

1.2 An Overview of Advanced Cutting and Joining Processes

Micro components often require to have very tight tolerances as well as fine surface quality for their use in modern appliances ; this has necessitated the use of appropriate advance cutting and joining processes [4, 5]. Industries such as the aircraft industry, nuclear plant industries, industries using sophisticated equipment as well as manufacturing industries are in dire need of advanced cutting and joining processes. Advanced cutting processes are classified according to the working media or the type of media for transfer of energy for the cutting operation such as high-velocity particles, reactive media, electrolyte, electrons and radiation. Another important classification is based on the cutting principle such as material removal using erosion, shear, chemical ablation and vaporisation. They can also be classified according to the source of energy, for example pneumatic pressure and hydraulic pressure . The classification of advanced cutting processes is shown in Fig. 1.1.

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Fig. 1.1

Classification of advanced cutting processes

The selection of appropriate advanced cutting process depends on a number of considerations which include the type of material to be cut, the economy of the process for the material and the required tolerance and surface finish. Each of this class is analysed in the following subsections which will help in the selection of appropriate process for any project at hand.

1.3 Mechanical Machining Processes

Mechanical machining process is an important advanced cutting process that can be used to cut different types of materials [6–11]. The cutting action is achieved by high-velocity moving fluid that erodes the materials on its path with the aid of high pressure. Water jet machining (WJM) [10, 11], abrasive jet machining and ultrasonic machining (USM) [7] are examples of mechanical machining process . In mechanical machining process, high-velocity fluid coming from nozzle with high kinetic energy induces a very high stress as it comes in contact with the workpiece material. When the induced pressure is higher than the ultimate tensile strength of the workpiece material, then the material begins to be eroded. The working media in mechanical machining processes are relatively cheap. The operating maintenance is low, since the only moving part used in the process is the pump. Complex designs can be cut with this process. The process does not cause damage of the workpiece due to low heat generated. Soft and hard materials can be cut effectively using these machining processes. The surface finish produced is very good. The high initial machine cost is one of the disadvantages of these machining processes and the material removal rate for fragile material such as glass is very low. The mechanical machining process is used for cutting, milling, 3D shaping, turning, drilling as well as polishing.

1.4 Chemical Machining

Chemical milling (CHM) and photochemical machining (PCM), also known as chemical blanking, are examples of chemical machining processes [1, 2]. Chemical machining uses corrosive agent as the driving energy through a corrosive media to cause material removal using corrosion process. Chemical machining is a controlled material removal process. The materials that should not be removed are protected by a special coating material called ‘maskants’. This material helps to protect the coated areas from attack by the strong chemical etchant or corrosive agent. The exposed areas, when they come in contact with the chemical reagent, are attacked by the chemical, thereby weakening the material and hence the material is removed. A number of hard-to-machine materials such as stainless steel, super alloys, ceramics, refractories and fibre-reinforced composite materials, due to their high hardness, strength and brittleness, can effectively be machined through this process. This process is used to achieve precision contouring of the workpiece into any shape and sizes through a controlled chemical attack on the workpiece. The main disadvantage of this process is that the process is very slow. Chemical milling of pockets, contours, chemical blanking and photochemical machining are produced with this process. Chemical machining offers a lot of advantages. The most important advantages include achieving decorative finishes and extensive thin-web area removal; it has low scrap rates, no burrs are formed, no stress is introduced to the workpiece, there is minimum part distortion and the machining of delicate parts is achievable. A continuous taper on contoured sections is achievable using the chemical machining process and the initial capital cost of the machine is relatively low. The main limitations of this process are that it involves handling of dangerous chemicals, the process is slower, operational cost is high and deep narrow cuts are difficult to produce. Chemical machining is used to produce geometrically complex and precision aerospace and electronic parts to mention but few. Miniaturised and microelectronics parts are easily achievable using the chemical machining process. A number of metals and non-metals such as aluminium, copper, zinc, steel, lead, titanium nickel, ceramic and glass can be effectively machined with this process. Large parts such as airplane wing that is made with aluminium can be machined with this process and the process can be used to machine miniaturised integrated circuit chips.

1.5 Electrochemical Machining

Electrochemical machining (ECM) process removes material from workpiece by dissolving atoms from the workpiece material based on the principles of Faraday [12, 13]. The passage of electric current between two electrodes that are dipped into electrolyte solution is known as electrolysis. Anodic reaction takes place at the anode while the cathodic reaction occurs at the cathode. The workpiece is the anode where material dissolution occurs [13–16]. The process can be used to cut or machine high-strength and heat-resistant alloys. Advantages of the electrochemical machining process include no wear in the tool due to non-contact between the workpiece material and the tool. The material removal is done at low voltage when compared to other processes and the material removal rate is relatively high. Small and microdimensions can be removed from the workpiece and complicated profiles can be machined easily in a single operation. The main limitations of this process are the fact that only electrical conductive materials can be machined, high initial investment cost and high operational cost. This process can be used to machine manifold, guide plate, tubes and drill-inclined holes.

1.6 Electrothermal Machining Process

Laser beam machining (LBM) and electron beam machining (EBM) are examples of electrothermal machining process [17–22]. Material removal is achieved by vaporising the material to be removed by using thermal energy. The laser beam is used to vaporise material and remove in LBM process , while in EBM process electron beam gun generates high-velocity electrons and the high-energy electron beam is made to impinge on the workpiece to vaporise the material to be removed. The high-velocity electrons are converted to heat energy as the electrons hit the workpiece. Electrothermal machining process has a number of advantages which include high metal removal rate and it has low heat-affected zone. The main limitations of this process are the high equipment cost and high maintenance cost. An important point to note is that these advanced cutting processes are suitable for machining micro- and nano-component with high accuracy and precision [4, 5, 23, 24].

1.7 Advanced Welding Processes

Advanced welding processes that are presented in this book are divided into basic types namely the advanced fusion-state welding and advanced solid-state welding. The laser beam welding and electron beam welding processes are the two advanced fusion welding processes that are dealt with in this book [25, 26]. The laser beam welding process uses the energy produced by the laser to melt the surface of the material to be joined and when it solidifies a strong weld is produced. Electron beam welding uses the high kinetic energy of high-velocity moving electron beam to melt the surface of the material to be joined when the electron impinges on the material, converting the kinetic energy to heat energy that melts the material. Upon solidification, a strong weld is produced on the material. These advanced welding processes have provided solutions to some industrial joining problems, most especially the small heat-affected zone produced by these welding processes and the ability to control the beam to the needed area without interfering with the surrounding materials. Intricate parts can also be joined with ease.

The advanced solid-state welding processes that are dealt with in this book are the ultrasonic welding , explosive welding and resistance welding. The ultrasonic and resistance welding are advanced welding processes that achieve the joining operations by bringing the surfaces to be welded into a plasticised state through the action of friction that is created between the surfaces. In ultrasonic welding, the friction is created by the vibration of the electrode, while in the resistance welding the friction is created by the resistance to the passage of electricity under pressure between the surfaces to be joined. The friction in both cases generated a lot of heat sufficient to plasticise the surfaces. This heat in combination with high pressure produced a strong weld. The explosive welding on the other hand achieves the welding operation through the action of explosive chemical placed on top of the material to be joined that is detonated in a controlled manner. These welding processes are achieved in the solid state of the materials and do not cause great damage to the microstructure of the material. These welding processes can be used to join materials at micro- and nanoscale levels.

1.8 Advantages of Advanced Cutting and Joining Processes

Advanced machining processes are useful in the fabrication of difficult-to-machine materials which are useful in many high-tech applications. The traditional machining process has limitations in their ability to effectively machine these materials. Modern material requirement necessitates the development of materials that have high hardness and high temperature resistance that make machining such materials a highly challenging one. These advanced machining processes are contact-less machining processes that help to offset the need for finding harder tool material than the workpiece material in the conventional machining processes. High production rate can be guaranteed for these difficult-to-machine materials when these advanced machining processes are used. The demand from manufacturing process in terms of tolerances is becoming tighter. Tolerances at nanoscale levels are often desired in the machining of some micro-sized parts and can only be achieved using these advanced cutting processes. Machining of highly complex-shaped part can only be machined using these advanced cutting processes. High-density micro-size holes on thin plate used in filters in the textile and food industries cannot be produced using conventional cutting processes. Advanced machining processes are effectively used to produce such holes and at high production rate. Advanced welding processes that are dealt with in this book are beneficial to the modern manufacturing needs that include joining of materials at micro- and nanoscale levels which are desired in the fabrication of many high-technological gadgets, sensors and electronic devices.

1.9 Limitations of Advanced Cutting and Joining Processes

The initial investments in most of these advanced cutting and joining processes are very high and also with high operational cost. The machining process performance is dependent on properties of the material to be machined.

1.10 Summary

Advanced cutting process is an important machining process that is used in modern manufacturing system. The current demand of high-performing materials and the need for high-performing appliances have led to the development of advanced materials that come with their own challenges. Most of the advanced materials are difficult to machine using the conventional machining processes. Some of the difficulties posed in machining these advanced materials are as a result of physical contact between the workpiece and the cutting tool material in the traditional manufacturing process. Advanced cutting processes that are presented in this book are contact-less machining processes which make these machining processes to be suitable for cutting difficult-to-machine materials. The different classes of advanced cutting and welding processes are introduced in this chapter. The full detail of each of these processes is presented in various chapters of this book. The book also presents the application of these advanced cutting and joining processes in micro- and nano-fabrication processes. These processes are also revolutionary because difficult-to-join and difficult-to-machine materials using the conventional joining process are easily joined or machined using these processes. Micro- and nanosized components and dissimilar materials can effectively be joined using these advanced joining processes. The detail of these advanced joining process is presented in the section B part of this book.

Acknowledgment

This work was supported by the University of Johannesburg research council (URC) fund and University of Ilorin.

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© Springer International Publishing AG 2018

Rasheedat Modupe  Mahamood and Esther Titilayo  AkinlabiAdvanced Noncontact Cutting and Joining TechnologiesMechanical Engineering Serieshttps://doi.org/10.1007/978-3-319-75118-4_2

2. Chemical Cutting Process

Rasheedat Modupe Mahamood¹, ²   and Esther Titilayo Akinlabi¹

(1)

Department of Mechanical Engineering Science, Faculty of Engineering and the Built Environment, University of Johannesburg, Auckland Park Kingsway Campus, Auckland Park, Johannesburg, South Africa

(2)

Department of Mechanical Engineering, Faculty of Engineering, University of Ilorin, Ilorin, Nigeria

Rasheedat Modupe Mahamood

Keywords

Chemical machiningChemical millingPhotochemical millingEtchantProcessing parameters

2.1 Introduction

Corrosion as it is known causes damage to materials. The same corrosion can become useful for fabrication of some high-valued parts if carefully controlled. Chemical machining is an advanced material removing process that uses chemical reaction called corrosion to remove material from parts. The material removal in this machining process is achieved by the action of etching or chemical corrosion. The machining process consists of chemical milling, chemical drilling, chemical grinding and photochemical milling . These machining processes have been successfully used to cut various materials successfully. A number of materials have also been successfully machined using these chemical machining processes. Ceramics , metals and alloys have been machined with chemical machining and have been reported in the academic literature [1]. The areas of interest in the part to be machined are exposed to the chemical attach in this process. This is done by protecting other areas using a special coating known as maskants. Maskants help to protect those areas from the part that is not intended to be removed. A number of profiles can be produced using these processes which include pockets and contours. The chemical processes can be used to also remove materials from high strength-to-weight ratio materials. Before the chemical machining process is performed, the surface of the workpiece to be machined needs to be prepared and cleaned to become free from dirt or lubricant. This prepared surface will enable the coating material to have proper bonding with the areas that need to be protected from the corrosion action. Also, the exposed surfaces will have proper reaction with the chemical reagent to be used without any forms of dirt interfering with the corrosion process. Different types of masks are available and the type of mask to be used will depend on the type of resolution required, the size of the workpiece and the number of parts to be produced. For tight-tolerance job, silk-screen masks are used. In the chemical machining process, the depth of the material to be removed is governed by the time of immersion. Moderate workpiece agitation in the etchant is also required for successful chemical machining. The rate of the chemical reaction can be increased by increasing the temperature of the etchant. The chemical machining process is extensively used in the manufacturing of parts such as electronic printed circuit boards, airplane body, shadow masks for cathode-ray tubes, jewelleries and nameplates, in the electronics, aerospace, precision engineering and jewellery industries. Five basic steps are involved in the chemical machining process. The first step has to do with workpiece preparation. The surface of the workpiece must be free from dust, dirt or grease in order to ensure a successful process. After the proper cleaning of the workpiece, appropriate mask is used to coat the material in the second step. The required design is then scribed on the mask placed on the material to reveal the area that needs to be etched. After the necessary preparation of the workpiece the fourth step is the actual etching process. The workpiece is immersed in the chemical reagent usually