关键词:
ANOVA
EDM
Microcrack
Taguchi
Tungsten carbide
摘要:
Electrical discharge machining (EDM) is the main process to make tungsten carbide (WC-Co) moulds and dies. Normally, the EDM process generates microcracks on the surface of the work piece. Consequently, the life time of the moulds or tools can be shortened because of defects in the product parts. This paper is an investigation on the optimal process parameters to minimize the microcrack density (***), electrode wear ratio (EWR) and maximize material removal. To reduce the number of experiments, the Taguchi design using an L9 orthogonal array was used. Analysis of variance (ANOVA) and signal-to-noise (S/N) ratio were performed and calculated, respectively. The important control parameters were the following: discharge current, off time, and open-circuit voltage. The experimental work pieces were composed of tungsten carbide, and graphite electrodes were used. Using the Taguchi approach, the significant factors of MRR, EWR, *** and their associated levels on each response were determined by ANOVA analyses. The discharge current parameters mainly affected the MRR, EWR and ***. Additional experiments confirmed the optimal process parameters at the 95% confidence interval. Micrographs from a scanning electron microscope (SEM) were used to study the density of microcracks on surfaces machined by EDM. © EuroJournals Publishing, Inc. 2011.