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.

No abstract

No abstract

Rotational autofrettage is a recently proposed method to induce beneficial residual stresses in axisymmetric hollow cylindrical bodies. The feasibility of the process has been studied for both disks and cylinders used in many engineering applications. The earlier analyses of rotational autofrettage of disks are based on certain assumptions. One of the crucial assumptions is the free rotation of the disk. However, the free rotation of the disk is practically difficult. In practice, it is feasible to rotate the disk by shrink-fitting it over a solid cylindrical mandrel. In view of this, a design of a disk-mandrel assembly for achieving rotational autofrettage in disks is proposed in this article. The main aim of the design is to obtain appropriate values of the disk-mandrel interference and the rotational speed of the assembly to prevent the loss of contact of the disk with the mandrel during rotation. The critical speeds corresponding to the yield onset, contact separation and the full plastic deformation of the disk are obtained as a function of shrink interference. The safe operating design parameters can be decided by plotting the critical speeds with varying interference values. A detailed stress analysis during elastic-plastic loading of the assembly followed by the analysis of residual stresses in the assembly after unloading is presented. The analysis is based on the plane stress assumption, Tresca yield criterion and elastic unloading. The analysis is validated with a finite element method model in ABAQUS. The proposed design is illustrated through the numerical example of an ASTM A723 disk-mandrel assembly to achieve rotational autofrettage in the disk. With a small overstrain level of 17.5% in the disk, a large magnitude of compressive residual stress, viz., 0.52 times the yield stress, is induced.

No abstract

No abstract

With the objective of demonstrating the basic concepts of computer-aided design of digital systems, an interactive graphics software package has been implemented. Examples of functional level simulation of control and arithmetic units of a hypothetical computer have been considered at gate and register levels respectively.