Springer Science and Business Media LLC

The compliance of an integrated approach, principal component analysis (PCA), coupled with Taguchi’s robust theory for simultaneous optimization of correlated multiple responses of wire electrical discharge machining (WEDM) process for machining SiCP reinforced ZC63 metal matrix composites (MMCs) is investigated in this work. The WEDM is proven better for its efficiency to machine MMCs among others, while the particulate size and volume percentage of SiCp with the composite are the utmost important factors. These improve the mechanical properties enormously, however reduce the machining performance. Hence the WEDM experiments are conducted by varying the particulate size, volume fraction, pulse-on time, pulse-off time and wire tension. In the view of quality cut, the most important performance indicators of WEDM as surface roughness (R a), metal removal rate (MRR), wire wear ratio (WWR), kerf (K w) and white layer thickness (WLT) are measured as responses. PCA is used as multi-response optimization technique to derive the composite principal component (CPC) which acts as the overall quality index in the process. Consequently, Taguchi’s S/N ratio analysis is applied to optimize the CPC. The derived optimal process responses are confirmed by the experimental validation tests results. The analysis of variance is conducted to find the effects of choosing process variables on the overall quality of the machined component. The practical possibility of the derived optimal process conditions is also presented using SEM.

To investigate the application of reformed coke oven gas (COG) in producing the direct reduction iron (DRI), we simulated a countercurrent gas solid moving bed reactor in which the iron ore pellet was reduced by reformed COG. An ordinary differential equation (ODE) was set based on the unreacted shrinking core model considering both mass and energy balances of the reactor. The concentration and temperature profiles of all species within the reactor were obtained by solving the ODE system. The solid conversion and gas utilization were studied by changing gas flow rate, solid flow rate, reactor length, and the ratio of O/CH4 to guide the practical application of COG in DRI production. Model results showed that COG was suitable for the DRI production. In order to meet the requirement of the industrial production, the minimum gas flow rate was set as 130,000 Nm3/h, and the maximum production was 90 t/h. The reactor length and the mole ratio x(O): x(CH4) were depended on the actual industrial situations.

The purpose of this study was to develop a closed-loop machine vision system for wire electrical discharge machining (EDM) process control. Excessive wire wear leading to wire breakage is the primary cause of wire EDM process failures. Such process interruptions are undesirable because they affect cost efficiency, surface quality, and process sustainability. The developed system monitors wire wear using an image-processing algorithm and suggests parametric changes according to the severity of the wire wear. Microscopic images of the wire electrode coming out from the machining zone are fed to the system as raw images. In the proposed method, the images are pre-processed and enhanced to obtain a binary image that is used to compute the wire wear ratio (WWR). The input parameters that are adjusted to recover from the unstable conditions that cause excessive wire wear are pulse off time, servo voltage, and wire feed rate. The algorithm successfully predicted wire breakage events. In addition, the alternative parametric settings proposed by the control algorithm were successful in reducing the wire wear to safe limits, thereby preventing wire breakage interruptions.