Optimization of A Plastic Waste Crushing Machine for Enhanced Crushing Efficiency, Throughput and Energy Economy

Abstract

Plastic waste accumulation remains a major environmental challenge, particularly in developing countries with limited recycling infrastructure. This study developed and optimized a low-cost plastic waste crushing machine suitable for small-scale recycling applications. Response Surface Methodology (RSM) based on a Box–Behnken Design was used to investigate the effects of rotor speed, blade angle, and feed rate on crushing efficiency, energy consumption, and material throughput. Experimental data were fitted to quadratic models and evaluated using ANOVA. The models showed high predictive accuracy with an F-value of 26.45, p < 0.001, R² = 0.968, adjusted R² = 0.942, and a non-significant lack-of-fit (p = 0.75), confirming model adequacy. Rotor speed was identified as the most influential factor, followed by blade angle and feed rate. Crushing efficiency increased with rotor speed and moderate blade angles but declined at excessive feed rates due to chamber congestion. The optimum operating conditions for maximum crushing efficiency were a rotor speed of 1325 rpm, blade angle of 38°, and feed rate of 3.8 kg/h, producing a crushing efficiency of 86.9% and energy consumption of 0.56 kWh/kg. The optimum material throughput of 4.67 kg/h was achieved at a rotor speed of 1312.5 rpm and feed rate of 4.0 kg/h with a blade angle of 38°. The mean prediction error of approximately 0.76% demonstrated excellent agreement between experimental and predicted results. The optimized machine exhibited high efficiency, low energy consumption, and satisfactory throughput, making it a technically viable and economically sustainable solution for decentralized plastic waste recycling and circular economy initiatives.