Abstract. The optimization technique of machining parameters considering multiple performance characteristics of non conventional machining EDM process using Taguchi method combined with grey relational analysis (GRA) is presented in this study. ST 42 steel was chosen as material work piece and graphite as electrode during this experiment. Performance characteristics such as material removal rate and overcut are selected to evaluated the effect of machining parameters. Current, pulse on time, pulse off time and discharging time/ Z down were selected as machining parameters. The experiments was conducted by varying that machining parameters in three different levels. Based on the Taguchi quality design concept, a L27 orthogonal array table was chosen for the experiments. By using the combination of GRA and Taguchi, the optimization of complicated multiple performance characteristics was transformed into the optimization of a single response performance index. Optimal levels of machining parameters were identified by using Grey Relational Analysis method. The statistical application of analysis of variance was used to determine the relatively significant machining parameters. The result of confirmation test indicted that the determined optimal combination of machining parameters effectively improve the performance characteristics of the machining EDM process on ST 42 steel.

Smallholder coffee farmers can increase their income and competitiveness by increasing the quality of green beans produced. One of the suitable coffee bean processing technologies to be adopted in Telemung Village, Banyuwangi Regency, East Java is honey processing method. This method will produce green beans at twice the selling price of traditional processing. This quantitative research involved 15 respondents as smallholder coffee farmers. The sample in this study uses a purposive sampling technique, namely farmers who have received training on the honey processing method. The data were collected using a structured questionnaire with face-to-face interviews. The analysis showed a significant relationship between perceived ease of use and intention to adopt the technology (r= 0.724; p= 0.002), and this result was supported by a significant correlation between perceived ease of use and perceived usefulness (r= 0.730; p= 0.002). It can be concluded that farmers have a positive perception regarding the ease of use and usefulness of the honey process method. However, the barrier to technology adoption is marketing uncertainty and this technology has not been practiced in the local community.

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This research was carried out on electrochemical machining (ECM) process using a workpiece material of SKD 11 tool steel and electrode of brass. Three process variables, i.e., voltage, electrolyte concentration and gap width with three levels for each process variables investigated. Based on the number of process variables and its level, an orthogonal array of L9 and two times replications employed in the design of the experiment. Setting a combination of significant machining parameters to maximize the material removal rate and minimize the surface roughness of the workpiece based on the results of optimization using the Taguchi method and weighted principal component analysis is a combination of voltage factors at level 3 of 48 V, electrolyte concentration at level 2 of 150 g/l, and gap width at level 1 of 1 mm. Machining parameter that has the greatest contribution is an electrolyte concentration which is 41.98%, then the contribution of voltage of 32.33%, and the gap width is 5.63%. Based on the results of confirmation experiments reveal that principal component analysis can effectively acquire the optimal combination of cutting parameters.

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