DESIGN AND OPTIMIZATION OF A COST-EFFECTIVE PLASTIC CRUSHING MACHINE FOR SMALL-SCALE RECYCLING APPLICATIONS

ABSTRACT The increasing accumulation of plastic waste poses a significant environmental challenge, particularly in developing regions where large-scale recycling infrastructure is limited. This study addresses this problem through the design and optimization of a cost-effective plastic crushing machine intended for small-scale recycling operations. The machine was developed to provide an affordable, energy-efficient, and reliable solution for local recyclers. Using Response Surface Methodology (RSM) based on a Box–Behnken Design (BBD), the effects of rotor speed, blade angle, and feed rate on the machine’s crushing efficiency, energy consumption, and material throughput were systematically investigated. A second-order regression model was developed and statistically validated, showing strong reliability (R² = 0.968, Adjusted R² = 0.942, F = 26.45, p < 0.001). The optimum parameters were found to be 1325 rpm rotor speed, 38° blade angle, and 3.8 kg/hr feed rate, yielding a crushing efficiency of 86.9% at an energy consumption of 0.56 kWh/kg. Throughput analysis indicated a maximum output of 4.67 kg/hr at 1312.5 rpm and 4.0 kg/hr feed rate. Response surface and contour analyses revealed a broad, stable operating region, indicating that small deviations from optimal conditions result in negligible performance losses. The study concludes that the developed machine design is technically efficient, economically viable, and environmentally beneficial, providing a sustainable solution for decentralized plastic recycling and contributing to waste reduction and circular economy development.