Micro and Precision Manufacturing

Accelerated trend of miniaturization and thereby increasing use of microfeatures and microparts have tremendously encouraged scientists and engineers to develop new techniques for their precision fabrication. Considering that, this chapter introduces various machining techniques for microfeature fabrication, their capabilities, salient features and associated surface integrity aspects. It also reviews the past work and highlights recent technological development in this area.

This chapter introduces basics of electrochemical micromachining (ECMM). In this process, no mechanical contact between tool and workpiece occurs, and machinability is not connected with material mechanical properties, and therefore, it is an attractive technology, especially when shaping 3-D sculptured surfaces in difficult-to-cut materials. However, the key problem in ECMM is to localize dissolution to achieve satisfactory accuracy. In this chapter, specificity of electrochemical micromachining and recent trends in this area are presented. The conditions of electrochemical dissolution are discussed, and the possibilities of shaping accuracy increase are indicated in details. The special attention is paid to the results of application of voltage pulses and integration with other technologies in hybrid and sequential machining.

This chapter describes the role of photochemical machining (PCM) in micromanufacturing and discusses the critical issues in this process. The competitive market has witnessed a rapid increase in demand of low-cost microcomponents and microproducts in various industrial sectors including medical implants, optics, automotive, electronics and biotechnology. Photochemical machining is a low-cost process for the manufacturing of such miniature components and parts. Photochemical machining requires chemically stable resist mask with superior adhesion quality. The photoresist chemistry and image development technology plays an important role in precision manufacturing. This chapter has reviewed the development of photoresist chemistry and image development technology which improves the performance and yield. The chemistry of photoresists is very complex due to the different components and the component characteristics required for each photoresist. This chapter explains the role of oxygen, photoinitiator, free radical formation and exposure time in photoresist. Review of the various assisted processes of PCM such as magnetic field-assisted PCM and ultrasonic-assisted PCM is discussed.

This chapter sheds light on the role and use of nanotechnology in manufacturing. The theme of this chapter is basically focused on nano-machining, nano-joining and welding, and nano-EDM technologies exploited for the production of precision engineered parts and components to cater the need of increasing global trend of miniaturization. Major nano-techniques in the aforementioned manufacturing areas, their development, current trend, salient features, and applications are exclusively discussed in this chapter.

The demand of ultraprecision optical components is increasing extensively with the rapid development of the modern optics. The optical components used in X-ray microscopy and extreme ultraviolet lithography (EUVL) demand surface roughness of about 0.1 nm rms, a figure accuracy about 1 nm peak-to-valley (p–v) and no induced subsurface crystallographic damage. Furthermore, an aspherical surface is gaining more interest over the past few years for its favourable properties, and many new optical materials are also being developed. Fabrication of ultraprecision optical components became a great challenge to the optical fabrication industry. Aspheric optical components are generally fabricated by shaping methods followed by precision finishing processes. Near net shape of the component can be accomplished by the shaping methods (e.g. single-point diamond turning, deterministic micro-grinding, etc.). The application of optical components fabricated by this method is limited to the infrared (IR) optics owing to the presence of high-spatial-frequency surface irregularities which lead to the possibility of scattering for shorter wavelength applications. Desired surface finish, figure accuracy and surface integrity can be attained by precision finishing techniques to make it suitable for shorter wavelength applications. In the recent years, ion beam figuring, elastic emission machining, nanoparticle colloid jet machining and magnetorheological finishing are extensively used for fabrication of ultraprecision optics. In this chapter, principle mechanism of material removal and applicability of aforementioned ultraprecision finishing processes to different materials are discussed.

This chapter looks at the condition monitoring of the micro-injection moulding process (µ-IM). This manufacturing process has been applied successfully to a wide range of products in the micro-scale and is also an appropriate technology for manufacturing meso-parts with both micro- and nano-features. Improvement in the quality and the accuracy of parts made from polymers can be successfully achieved by determining the optimum conditions for replication. Process control in manufacturing is critical, and condition monitoring of µ-IM is a control method for improved understanding of the effects of selected parameter settings. This chapter reports on the condition monitoring methods used to improve the factors that affect part’s quality. For each of the examples, the Taguchi design of experiments (DOE) method is used together with demonstrations of various experimental set-ups and the acquisition of data. The chapter advises on the obtainment of information regarding the behaviour of the µ-IM and the significant factors affecting the process. The selected case studies demonstrate the condition monitoring of the cavity pressure, forces, temperature distribution and air evacuation. For each, the research findings are discussed and conclusions are made.

Unlike materials subtractive technologies, additive manufacturing (AM) works on producing near-net-shape components according to a specific design at which the synthesis is achieved layer by layer. Additive manufacturing allows design freedom, making design-driven manufacturing a reality. However, its poor surface quality is considered as one of the key challenges that are worth to overcome. The main objective of this chapter is to report a comprehensive overview of the techniques used to improve the surface finish and their advancements of products made by metal additive manufacturing (AM) technologies and to highlight experimental processes and data. Powder bed fusion (PBF) and direct laser deposition (DLD) are the main processes covered in this review. The chapter starts with the literature review and introduction to the main metal AM processes and their surface roughness limitations, the effect of their parameters and the effect of the laser re-melting on the surface quality. Next, it is followed by a number of surface finishing techniques such as laser polishing, chemical and electropolishing. Experimental results of post-surface finishing of AM parts by microelectrical discharge machining are also presented.

Precision coatings are used to fulfil various surface engineering requirements such as to provide necessary protection to the surface of an engineered part, to impart necessary strength or hardness, or to increase its aesthetics. This chapter introduces various important surface coating technologies. It starts with presenting the concepts of universal underlying considerations—functions of coatings and then moves to addressing the different types of coatings. The method(s) and area of application, and the performance properties are presented for each coating category. Furthermore, this chapter aims to provide an effectiveness comparison of different coating types, enabling the reader to find the proper coating system for a particular application. In addition, some quality and precision aspects are presented. In this regard, the chapter discusses the main issues regarding the quality control of coatings, verification means, inspection equipment, as well as the applicable standards. Finally, the chapter is concluded with some practical examples of precision coatings applied on gear teeth for increasing their wear resistance and for improving their dynamic behaviour (vibration) and reducing the acoustic emission (sound level).