Rancang Bangun Prototipe Alat Sortasi Ukuran Biji Kopi Robusta Dengan Variasi Sudut Kemiringan Ayakan

Abstract

Sorting is an essential stage in the post-harvest processing of Robusta coffee to achieve uniform quality; however, the use of a sorting machine with a fixed inclination angle causes the bean flow to move too quickly, reducing screening effectiveness and still requiring manual labor. This study aimed to design and build a prototype of a Robusta coffee bean size-sorting machine with variations in the sieve inclination angle and to analyze the effect of these variations on machine performance. The study employed an experimental approach with inclination angle variations of 10°, 15°, and 20°, three replications, and analysis of variance (ANOVA). The results showed that the inclination angle had a significant effect on the machine's working capacity (45.55–70.05 kg/h); increasing the angle raised the working capacity and lowered energy consumption but decreased sorting efficiency from 74.95% to 71.97%. The mean weight diameter (MWD) of the sorted output remained stable at around 7.6 mm and did not differ significantly among the angles based on analysis of variance (ANOVA), indicating that the inclination angle affected separation precision rather than the mean bean size. The variable inclination-angle mechanism allows the operator to select the inclination angle according to operational priorities, whether prioritizing sorting quality or working capacity and energy efficiency.