Materials Forming, Machining and Post Processing

This chapter introduces the ways to characterize the materials for both sheet and tube materials. This mostly includes the tensile test for sheet metal, and tensile and ring test for tube metal. This also includes in providing the direction of inputting the material data in finite element simulations. The chapter further discusses the conventional method to form sheet and tube metal to the desired shape. Further, it will walk through the formability of metal and then introduce the novel techniques such as hydroforming, rubber forming, electric forming, incremental forming, roll forming, tailor welded blanks, and some high speed forming such as electromagnetic and explosive forming. In addition, conventional and rotational flaring, Reuleaux forming were discussed for tube forming. Further, some of the common challenges were discussed.

Near net shape metal injection moulding (MIM) process is employed to manufacture the complex shaped metal parts and can readily be used without the requirement of secondary processes. Appropriate control at various stages (i.e. feedstock preparation, injection moulding, binding, debinding, and sintering) of the MIM process is essential to obtain pore-free structure that yield good compact in MIM parts. In MIM process, the outputs (such as, surface roughness, micro-hardness, and ultimate tensile strength) of injection molded parts is influenced majorly by injection speed, feedstock flow velocity, injection temperature and mold temperature. The present work is focused to study and analyse the effect of influencing variables of nickel based (Cr₃C₂-NiCr + NiCrSiB) metal injection moulded parts using statistical Taguchi method. Taguchi method is employed to conduct actual experiments and Pareto analysis of variance is conducted to analyze and estimate the significant contribution of input variables on different outputs. Taguchi and Pareto ANOVA methods determine the different set of optimal levels for each output, separately. Determining single optimal level for all the outputs is often difficult due to the conflicting requirements (maximize: MH, UST; minimize: SR) in injection moulded parts. Therefore, Principal component analysis (PCA) is applied to determine the relative importance (weight fraction) for individual outputs. Grey relational analysis (GRA) is applied to convert the multiple objective functions with different set of weight fractions determined using PCA to single objective function through suitable mathematical formulation. The grey relation grading has been determined and single optimal levels for satisfying the conflicting requirements are solved in the present work. The hybrid Taguchi-GRA-PCA method determined optimal solutions are tested with practical experiments and resulted in better metal injection mould properties. The result could help any novice user to gain best properties in metal injection moulded parts.

The use of thermoplastic materials, specifically in automotive industry, is increasing exponentially due to their numerous overpowering quality characteristics in comparison of metals and alloys. Three-dimensional (3D) printing technologies are established as one of the best methods for fabricating customized, complex, durable and mechanically strong structures. However, such parts often required to be assembled when subjected to industrial applications, automotive sector for instance. The service life of the joints made with adhesives, glues and mechanical fasteners is greatly depending on working conditions, for e.g.: moisture. Recently, researchers have highlighted the utility of friction stir welding (FSW) of thermoplastics for a wide range of conventionally made thermoplastics structures and very less information is available on FSW of three-dimensional (3D) prints. This chapter outlines the recent research trends in FSW and a specified case study focusing optimization of tensile strength of the specimens, made with 3D printing, by friction stir welding (FSW). Further, as-welded and fractured specimens were analyzed through scanning electron microscopy to identify the joint quality and reasons of failure. It has been found that the chips formation of thermoplastic fibers while welding was the most critical issue, opening new research areas for forthcoming 3D printing and FSW practices.

With evolution and change in environment, Nature’s structures and its material system exists with products having multiple designs and dimensions. Inspired by Nature’s ability to develop structures with complexity, various research works are carried out to develop newer technology to build complex products with more design dimensions. In the process of bio mimicking nature’s fabrication process 3D printing has captured the imagination of everyone from industry to research experts. However, there are various challenges need to be addressed in the process of 3D printing related to material system and product functional dynamicity. Hence, to overcome the limitations of 3D printing in flexible product development, 4D printing was generated with one or more additional design dimensions. 4D printing invented by MIT research group relies on fast growth of smart materials, 3D printers, mathematical modelling and design, and shows advantages over 3D printing. This article presents a comprehensive overview of 4D printing concept, applications and future scope for research.

Nonconventional micromachining processes are developed to meet the manufacturing requirements of new materials and products where usual processes are found inadequate. Based on the type of energy used for material removal, the different micromachining processes are classified into thermal, mechanical, chemical and hybrid processes. Hybrid processes combine two or more machining processes to achieve the desired machining. Descriptions of the important micromachining processes, their material removal mechanism and salient application fields are dealt with in this chapter.

Surface integrity has a significant influence on mechanical and tribological behaviour of a material in high heat resisting applications. Non-traditional machining methods like electrical discharge machining (EDM), laser beam machining (LBM), electrochemical machining (ECM), ultrasonic machining (USM) etc. are commonly used to processes the hard materials. Wire EDM (WEDM) is most efficient spark erosion process to shape the hard materials into desired geometry and to modify their surface characteristics. In present book chapter, the experimental results pertaining to surface modification of difficult to machine materials namely WC-Co and Nimonic-90 are presented. Surface was modified through rough cut, trim cut and combination of rough and trim cuts in wire electrical discharge machining (WEDM). Surface integrity was measured in terms of surface roughness (SR), crack size and recast layer thickness. In all the cases, surface integrity was dissimilar for both the difficult to machine materials. Scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis was used to evaluate the surface morphology of WEDMed surfaces.

Nowadays with growing pollution and contamination by hydrocarbon (petroleum) based cutting fluids, the scope for vegetable or synthetic biodegradable esters based eco-friendly cutting fluids is increasing. In this review work, the main focus is on sustainable machining using advanced cutting fluid application techniques with eco-friendly cutting fluids. Understanding the functions and various types of cutting fluids are critically important to maximize its performance during any machining process. Also, cutting fluid application techniques are equally important to minimize the use of cutting fluids for the desired machining processes. This review article focuses on the conventional cutting fluids, function of cutting fluids, ecological aspects of conventional cutting fluids, eco-friendly cutting fluids, cutting fluid application techniques during machining and their performances in order to establish the research field further. An overview of the role of eco-friendly cutting fluids and cooling techniques are discussed and finally concluding remarks and possible scope of future work is presented.

This chapter presents details of cryogenic machining of titanium alloys. It discusses different innovative methods used in literature for cryogenic machining of titanium alloys. A detailed methodology is presented to design a sustainable cryogenic fluid delivery setup. It also covers economic aspects of cryogenic machining in comparison to dry machining. Finally, a sustainable liquid nitrogen delivery setup is designed and developed to perform cryogenic machining of Ti-6Al-4V. The design of this retrofittable cryogen delivery solution for a range of available machine tools shall provide a direct cost based impetus for improving machining of such materials, which at present does not exist for indigenous industry. For experimental analyses, three machining process parameters i.e. the cutting speed (v), feed (f) and depth of cut (d), and different machining environment i.e. dry and cryogenic are selected. Response variables selected for this study are surface roughness, resultant force and power consumption. Experiments are designed as per hybrid design of experiments (DoE) technique. Hybrid DoE is a combination of orthogonal array and full factorial methods. To investigate the results, each combination of process parameters are compared under dry and cryogenic machining. Analysis of variance technique (ANOVA) is used to reveal the effect of process parameters on response variables. The results show that better surface finish obtained under cryogenic machining in comparison to dry machining. Results of power consumption suggest suitability of cryogenic machining over dry machining at higher levels of process parameters.

Materials are subjected to surface treatments in order to alter the nature both physically and chemically. Also there are certain mending process of surface defects can be carried out using surface treatment process. The current chapter primarily focusses on exploring the impact of advanced surface processing techniques like laser glazing, laser shock peening and laser annealing. The three types of additive manufacturing are laser additive manufacturing, wire arc additive manufacturing and cold spray deposition technique. The effect of the various process parameters of the respective process are discussed in detail. The discussion is primarily focused on the development of shape memory alloy structures using the techniques mentioned and an analyses on the nature of the developed alloys. The surface morphology of the developed structures were evaluated using Scanning Electron Microscopy (SEM), The micro-hardness test reveals the mechanical properties of the samples. All the characterized results showed that SMA could be manufactured successfully using the mentioned techniques, though each system have their own pros and cons. Hence this chapter will give the researchers in beginning stage a clear idea about the evolution of near net shape manufacturing systems that can be used by their research works in developing novel research ideas.

LASER cladding technology has a strong applicability in the surface coating sector, mainly in metallic surfaces, although, it has been arousing, more and more, the interest in the components repair and rapid prototyping sector. The reason for its creation was to improve the quality of component surfaces, overcoming the already known disadvantages in traditional processes as TIG—Tungsten Inert Gas welding also known as GTAW—Gas Tungsten Arc Welding, plasma spray or HVOF—High Velocity Oxy Fuel, being these disadvantages the high dilution of the substrate material into the coating/cladding, the large increase of temperature imposed by the process resulting in distortions in the parts, the low precision in material deposition, porosities, micro-cracks, bond defects and problems in the adherence to the substrate. The application of LASER technology for material addition/deposition processes come, for example, to improve the precision of the material deposition, to reduce the dilution of the substrate and the temperature increase of the component to be coated and also, the utilization of a LASER beam, does not cause unfavourable alterations in the mechanical properties of the melt pool. LASER cladding technology can be considered interdisciplinary, in so far as it includes various technological areas, namely the LASER technology, drawing area and computer assisted production, the robotic and control area and also the area of powder metallurgy. The majority of the scientific publications about LASER cladded coatings refer mainly its use in materials from aerospace, medical and automotive industries. Therefore, this chapter will attempt to focus on the LASER Cladding growing applications of this recent technology and advantages and limitations of this process. This chapter will begin with a historic description of the LASER Cladding technology, followed by the principles of the process operation, the applicability of the process, the state of art of materials utilized in the Cladding process, and the advantages and limitations of the process. At the end of the chapter will be present the recent developments in LASER Cladding process.

Development on austenitic stainless steel and nickel-based superalloys have played vital role in the field of manufacturing of engineering components. The selection of materials depends upon working environment and operating conditions. In some cases, the combination of two different materials is used to join and apply them for specific working conditions. Joining of stainless and super alloys for turbine power shaft and high temperature steam pipe lines are the two major examples of this. Challenges in current research are to join dissimilar materials without disturbing the properties of parent metals. Materials joining process either may be at fusion state or solid state. Extensive research articles are available to discuss about the joining process of similar materials. While considering the dissimilar materials, individual conditions has to be satisfied depending upon the choice of joining process. Sample thickness, weld energy required, filler material, weld speed, weld design, etc. are the pre-requisite for completion of the process. The weld zone heat transformation (thermal gradient) thickness and its metallurgical quality are the major outcome in welding process. In this chapter, the research is focused on joining of two different metals using laser and electron beam welding (EBW) process. The metallurgical changes in the weld zone are studied. Further, the electrochemical behaviour of austenitic stainless steel and nickel-based superalloy dissimilar weld has been studied using 3.5% NaCl solution. The samples exposed to corrosion medium are followed with metallurgical characterization techniques such as: Optical imaging, SEM, EDS and XRD. Results from the investigation indicate that the EBW sample is superior than laser beam welded sample. The heat convention under laser welding has induced the samples to metallurgical deficiency.