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The thickness of recast layers produced during electrical discharge machining (EDM) is an important process performance measure as it may indicate an extent of crack propagation in a machined surface or thickness of a functional layer alloyed onto a machined surface. Thus, the availability of the recast layer thickness prediction models is needed to allow better control of machining outcomes, which becomes more vital for micro-EDM due to the microscale of machined features. The proposed numerical model, based on a multiple discharge approach for recast layer prediction, is developed to fill an existing gap in micro-EDM. The multiple discharge approach accounts for the overlapping nature by which craters are generated on the machined surface and considers the recast layer to be a combination of individual recast regions from individual craters. The numerical analysis, based on finite element methods, is used to determine the melting isotherms due to heat inputs on overlapping crater profiles. Then, a hemispherical-capped crater profile is estimated by applying a recast plasma flushing efficiency to the amount of molten material bounded by the melting isotherm. Finally, the recast region is defined to be bounded by the melting isotherm and crater profile. The model, developed for a peak discharge current of 1.45 A and pulse on time between 166 ns and 606 ns, predicted recast layer thicknesses of between 1.0 [micro]m and 1.82 [micro]m. It is then validated at pulse on time settings of 244 ns and 458 ns, which generated average recast layer thicknesses of 1.18 [micro]m and 1.56 [micro]m, respectively. Thus, the numerical model developed using the multiple discharge approach is suitable for estimation of recast layer thicknesses in micro-EDM. [DOI: 10.1115/1.4001480] Keywords: microelectrical discharge machining, multiple discharge, numerical modeling, recast layer thickness

This paper investigates the compliance characteristics of contact wheels in robotic finishing process, especially pressure distribution – a key parameter for material removal. The current study tackles this problem by developing finite element models of compliant contact wheels to predict pressure distribution with respect to various tool-workpiece scenarios. These models are further verified using pressure film sensors with flat and serrated contact wheels mounted on a robot.

Byline: S.H. Yeo, W.M. Ang This paper explores the desirable relationship between business strategy and environmental strategy on both a product line and process line basis. The work uses the Analytical Hierarchy Process (AHP) to do a pair-wise comparison between business and environmental benefits and importance. Subsequently, the Product Profile Matrix is used to conceptualise the findings generated from the AHP and hence evaluating the product's/process standing in terms of the two important factors. This paper also demonstrates how such results help to facilitate the development of appropriate business and environmental strategies and hence to create a successful shift into a more desirable market position.

The research work describes an attempt to model the knowledge of an experienced process planner and NC programmer by engaging expert system techniques. An experimental system has been developed in order to satisfy the need for an integrated automated system in a machining-based manufacturing environment. The system adopts a frame-based approach for the generation of machining tasks for turned parts. [ABSTRACT FROM AUTHOR]

The gripper is the mechanical interface between the robot and its environment. Without it, the robot cannot perform the pick-and-place functions needed for assembly tasks. As with other peripheral equipment, grippers should have sufficient versatility to deal with the variety of parts an assembly robot has to handle. Yet the cost of grippers and peripherals should not be so high as to render a robotic assembly application uneconomic. This paper focuses on strategies to achieve versatile and cost-effective gripping. The three main sections of the paper cover existing techniques for making grippers more flexible, a strategy for minimizing the required number of grippers through part-family grouping, and a strategy for selecting and using grippers based on knowledge-engineering methodology. [ABSTRACT FROM AUTHOR]