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Surface roughness affects the performance and service life of the formed components. To this end, efforts have been spent in the innovative incremental sheet forming (ISF) process. However, the researchers yet have not reached any agreement regarding the process effects on roughness. This demands further research to comprehend the knowledge in order to acquire a threshold level of understanding on surface roughening in the process. The present study investigates the processing effects upon the roughness of interior surfaces and on the friction indicator at the tool/sheet interface during forming of an aluminum sheet. Some of the sparsely studied parameters, namely flow stress, sheet thickness, and forming angle, are undertaken besides commonly considered ones (i.e., tool diameter and step size). The analysis of the results reveals that the friction indicator and roughness are analogous in respect of their response to parameter variations. Further, the roughness in general linearly increases with an increase in the friction indicator because the sheet abrasion correspondingly increases as revealed by the SEM-based surface morphology. A combination of parameters, among several attempted ones, namely dsinθ/2pt (where d is the tool diameter, θ is the forming angle, p is the step size, and t is the sheet thickness), is identified to have controlling influence on the roughness of interior surfaces. This combination is validated employing two materials namely Al1060 and Cu/Steel composite. In this combination, the factor d/2p followed by 1/t is found to have the greatest contribution towards the roughening of surfaces. Moreover, the value of this combination is proposed to keep low in order to produce components with good finish, say ≤ 50 mm−1 for Al10160 and 20 mm−1 for Cu/Steel composite. The present and past roughness studies in ISF are also compared, which reveals that the parameters effects are associated to the type of material. [ABSTRACT FROM AUTHOR]

Single-point incremental forming (SPIF) of polymers was started back in the first decade of twenty-first century; since then, substantial studies have been performed on this topic. The present article reviews these studies and compiles the developments in a comprehensive manner. The review entails a number of forming aspects of polymers, the more important of which are deformation mechanics, failure modes, formability, forming forces, springback, and post-forming material characteristics. The agreements and disagreements amongst the researchers are recognized and critical remarks are provided. The issues are identified, and areas of future work are proposed to further comprehend knowledge on the subject in order to successfully deploy the process on industrial scale. The differences in the characteristics of SPIF of polymers and SPIF of metals are also outlined and discussed in this article. The review concludes that the operating parameters and material are the key factors that affect the process performance. Further, the innovative technology must be adopted, and a larger database should be established to enhance industrial viability of the process. [ABSTRACT FROM AUTHOR]

A new constrained flow mode was developed to improve the machining stability in pulse electrochemical machining (PECM) of micro channel arrays on metallic bipolar plate. In electrochemical machining (ECM), the electrolyte flow field in the machining region is a key factor influencing processing stability and surface quality. In this study, a multifunctional cathode (MFC) was designed in the process, which was prepared with casting molding method. MFC acted as electrode, as well as sealing device and isolating individual machining regions. The channels of electrode were filled with elastic blocks, which were tightly pressed against the surface of workpiece during process to separate the large machining region into multiple independent machining regions. Therefore, the machining area would have sufficient electrolyte, and the flow field of each channel was independent from each other. 3-D flow field simulation was developed in this study to analyze the flow field of the channel arrays. It indicated that multiple independent machining regions could effectively improve the velocity uniformity of each channel. The experiments revealed that the uniformity of flow field had a positive role to prevent from spark discharge and short circuit, as well as the machining efficiency and machining stability. The channel arrays with 466-μm depth were machined on SS304 metallic BP within 2 min. [ABSTRACT FROM AUTHOR]