Integrated optimization of machining accuracy and occupational exposure in ECDM of CFRP composite

Purpose The electrochemical discharge machining (ECDM) is extensively employed for micro-machining of non-conductive and composite materials; however, the generation of hazardous fumes during the process raises concerns regarding machining environment and operator safety. This study aims to investigate machining quality and fume exposure during ECDM of carbon fiber reinforced polymer composites. Design/methodology/approach Experiments were designed using a central composite design with process parameters varied within the ranges of voltage (35–55 V), electrolyte concentration (5–25%), electrolyte temperature (10–50 C) and duty cycle (50–90%). Hole overcut (HOC) and fume mass concentration (FMC) were selected as performance responses. Quadratic models were developed and validated using analysis of variance (ANOVA). Findings The developed models demonstrated strong predictive capability, with coefficients of determination of 0.9373 for HOC and 0.9671 for FMC. Applied voltage, electrolyte concentration and duty cycle were identified as significant factors influencing both responses. Increasing voltage from 35 to 55 V resulted in a rise in HOC and FMC from 62 to 121 µm and 15.80–35.78 mg/m3, respectively. Morphological analysis revealed fiber burning, irregular hole edges and profile distortion at higher discharge energies. Fume characterization indicated dense particle distribution with spherical, irregular and agglomerated shapes. Multi-response optimization using the desirability function approach yielded optimal conditions at 38 V voltage, 10% electrolyte concentration, 10 C electrolyte temperature and 54% duty cycle, achieving FMC of 14.33 mg/m3 and HOC of 58 µm. Originality/value This study provides a comprehensive assessment of both machining performance and environmental impact in ECDM of composite materials. It highlights the critical role of parameter optimization in simultaneously enhancing machining precision and minimizing hazardous fume emissions, contributing to safer and more sustainable micro-machining practices.