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Purpose Electron beam-based additive manufacturing (EBAM) is an emerging technology to produce metal parts layer-by-layer. The purpose of this paper is to systematically address the research and development carried out for this technology, up till now. Design/methodology/approach This paper identifies several aspects of research and development in EBAM. Findings Electron beam has several unique advantages such as high scanning speed, energy efficiency, versatility for several materials and better part integrity because of a vacuum working environment. Originality/value This paper provides information on different aspects of EBAM with the current status and future scope.

In this chapter, the authors study a weighted-((f / (r, s)), k)/ (m, n): G system. The system consists of mn components arranged in a matrix form and the system works if all the sub matrices of order (r, s), the total weight of the working components is greater than f and the total weight of the working components in the system is at least k. This chapter deals with the evaluation of fuzzy reliability and fuzzy mean time to failure of the considered system with the application of fuzzy universal generating function and fuzzy Rayleigh distribution. In this study, the authors formed some prepositions to understand the behaviour of the considered system with respect to different varying parameters and also present an illustrative example to understand them.

Anisotropy and omnidirectionality are the two most significant impediments to the growth of additive manufacturing (AM). While anisotropy is a property of the part, omnidirectionality is a characteristic of the machine tool. Omnidirectionality, implying invariance in AM processes with the goal of minimizing variations in material and geometric properties of the as-built parts, is often ignored during systems and process design. Disregard to directional sensitivity, which in some cases are inherent to the process (and/ or system), inadvertently changes the process parameter in-situ consequently, producing parts with non-uniform and often erratic properties. AM, attributing to its sheer number of processing variables, is especially susceptible to this subtle, yet significant system property. While some AM platforms, due to their nature of part production, are inherently omnidirectional, others require additional setup to ensure the same. Having an omnidirectional AM platform ensures that the parts are fabricated with process variables that are equally sensitive in all directions. In most AM systems, given a fixed set of process parameters, the spatial orientation of fusion (or joining) source vector, feedstock-delivery vector, and travel direction vector relative to each other governs omnidirectionality. Inconsistency or change in orientation of these three vectors results in non-uniform part properties and variations in geometric dimensions. Therefore, AM systems have to be omnidirectional to improve part performance and promote industrial acceptance. This paper, through a formal definition of omnidirectionality, analyses these three vectors individually along with their interplay with other process parameters and design variables.

Metal inert gas (MIG), Tungsten INERT GAs (TIG), laser and Electron beam (EB) cladding processes are used in cladding-based Additive manufacturing (AM). Only in the case of MIG, the raw-stock is fe...

As there are no cutting forces in High Energy Density (HED) beams like lasers and Electron Beam (EB), their speeds are limited only by their positioning systems. On the other hand, as the entire matrix of the 3D printed part has to be addressed by the thin beam in multiple passes in multiple layers, they have to travel several kilometers in tiny motions. Therefore, the acceleration of the motion system becomes the limiting factor than velocity or precision. The authors have proposed an area-filling strategy for EB to fill the layer with optimal squares to exploit analog and hardware computing. 3D printing requires uniform intensity slanged as flat hat shape whereas the default is Gaussian. The authors have proposed an optimal algorithm that takes into account the maximum velocity and acceleration for achieving a flat hat without any compromise on productivity.

Purpose The support structures of sacrificial material are built in deposition-based additive manufacturing (AM), which are later removed either by breaking or dissolving. Such a sacrificial material is not feasible in metal AM. The purpose of this study is to find a suitable method for eliminating the need of support mechanism. In this work, the authors use the tilting of the substrate to alleviate the need for the support mechanism altogether. Design/methodology/approach As in the traditional AM, the object is grown in horizontal layers. However, wherever undercuts are encountered, the substrate is tilted appropriately to capture the droplets. Such a tilt involves two rotary axes invariably. To conform to the slice geometry, these two tilts are accompanied by the three linear movements. Thus, the object with undercuts is grown in planar layers using five-axis deposition without any support structure. Each pair of the corresponding top and bottom contours of any slice defines a ruled surface. The axis of the deposition head will be aligned with the rules of this surface. Findings The need for the support mechanism was eliminated using five-axis deposition. This was experimentally demonstrated by building an aluminum impeller using a metal inert gas cladding head. Research limitations/implications In the proposed methodology, the objects with an abrupt change in the geometry are not possible to realize. Originality/value This manuscript proposed a novel method of eliminating the support mechanism through continuous five-axis deposition.

This paper deals with the introduction and study of fuzzy reliability measures of a linear m-consecutive weighted-k-out-of-r-from-n: F system. The paper provides an algorithm for the evaluation of fuzzy reliability of the proposed system based on application of universal generating function and fuzzy exponential distribution. It is assumed in the study that failure rate follows generalised symmetric trapezoidal fuzzy number in fuzzy exponential distribution. Further, generalised symmetric trapezoidal fuzzy number and its arithmetic operations are defined. Fuzzy mean time to failure and Brinbaum system fuzzy reliability importance is also calculated. A numerical example is also presented to illustrate the proposed approach.

In this study reliability analysis of non-repairable weighted k-out-of-n: G (F) systems by incorporating uncertainties namely aleatory and epistemic have been considered. To remove these uncertainties the combination of mass distribution, fuzzy exponential distribution and belief universal generating function have been used. The failure rate (λ) of each component is taken as trapezoidal fuzzy number. Using the proposed method fuzzy reliability function of each component have been calculated and then distributed masses among the components. With the help of these masses reliability and MTTF of the proposed system have been obtained. Lastly, a numerical example is taken to understand the proposed method.