Micromanufacturing processes are expanding in their length and breadth as long as the related research and development (R&D) activities and applications are concerned. Products are getting miniaturized and their performance efficiency is getting enhanced by the addition of micro/nanofeatures and devices. In the set of these two articles (Part I and Part II), an attempt has been made to review the latest R&D activities of the selected micromanufacturing processes. This article (Part I) deals with a review of the literature related to attrition (subtractive, or machining and finishing) processes (both types—traditional and advanced) including microturning, micromilling, microdrilling, abrasive jet micromachining, laser beam micromachining, electrochemical micromachining, magnetorheological finishing, abrasive flow finishing, magnetic abrasive finishing, ion beam micromachining and so on. Apart from the subtractive processes, an overview of the X-ray lithography has also been presented. An attempt has been made to report some applications to help the readers to evolve more new applications of these processes. At the end of different sections/subsections, some research areas have been identified, which would hopefully fill the gaps between the theoretical analysis, experimental work and applications.
This article discusses an overview of microforming, microcasting and microwelding processes. In the case of microforming, the processes reviewed are micro deep drawing, microforging, microextrusion, microrolling, microstamping, microhydroforming and incremental microforming. This section also throws some light on how the lasers have been used for microbending and micropunching purposes. The work done in the area of physics of microforming processes has also been discussed briefly. This article also deals with different types of microcasting processes particularly permanent mold and investment microcasting processes. The applications of these microcasting processes have been specified in different fields of engineering, biomedical and so on. Some areas in which further research work is needed have been identified. It includes both theoretical and experimental works which need attention. The last part of this article deals with microjoining in general and laser microjoining in particular. This section discusses the types of the lasers that are being used for microjoining purposes. The process parameters (laser, optics, system and material) have been explained, and some work done on the parametric analysis has been reported briefly. Various applications of laser microjoining have been elaborated before the last section on concluding remarks. This last section presents, in very brief, the areas in which further work is required in microjoining processes.
Tailored structures of Ni-Ti shape memory alloys for micro-electro-mechanical systems can be fabricated using laser additive manufacturing, and requisite homogeneous microstructure for predictive design and fabrication of micro-electro-mechanical systems devices can be achieved by annealing. Investigation has been performed on the laser annealing of laser additive-manufactured Ni-Ti structures using a pulsed green laser through numerical simulation and experimental studies. The parametric dependence showed that a laser energy density of 1100 mJ cm 22 has a considerable influence in annealing of Ni-Ti structures. The surface morphology, phase transformation temperature and microstructure of laserannealed Ni-Ti structures were studied with scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. Laser energy density of 1100 mJ cm 22 was used for annealing the samples as identified in the simulation. Surface annealing of Ni-Ti led to a uniform surface of the material with an increase in grain size and surface roughness. A decrease in the micro-hardness of the samples was obtained as a result of laser annealing. Thus, the investigations demonstrated the improved properties of laser additive-manufactured Ni-Ti structures by laser annealing.
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