Development Of A Friction Coefficient Apparatus For Granular Materials

ABSTRACT

The knowledge of coefficient of friction of agricultural granular materials on various structural surfaces is important in analysis and design of post-harvest handling, food processing and storage equipment. Measurements were made with an apparatus developed to determine static coefficient of friction of benniseed, finger millet, hungry rice and pearl millet for three different moisture content levels randomly, within the range of (4.3% to 17.4% wet basis) on five structural surfaces (glass, mild steel, plastic, plyboard and aluminum) Effects of various structural surfaces and different moisture content levels on the measured parameters (coefficient of friction) were determined. Both factors examined had a high significant effect (P< 0.05) on the coefficient of friction of the agricultural granular materials. The coefficient of friction obtained for benniseed ranged from 0.286±0.014 to 0.711±0.157 over a moisture range of 6.1 % to 17.4 %; hungry rice, 0.298± 0.018 to 0.683± 0.217 over a moisture range of 5.7% to 16.2%; finger millet, 0.240± 0.016 to 0.643+ 0.243 over a moisture range of 4.3% to 17.2% and pearl millet 0.257± 0.016 to 0.591± 0.114 over a moisture range of 4.8% to 15.5%. Plyboard showed higher values of coefficient of friction, followed by mild steel, plastic, aluminum and glass for all materials tested. Benniseed had the highest values of coefficient of friction, followed by hungry rice, finger millet and pearl millet with the least values. From the results of the analysis, the materials tested shows that coefficient of friction increased linearly with increase in moisture content for all the structural surfaces tested. Moisture content, structural surfaces and morphological variations of materials significantly affect coefficient of friction of agricultural granular materials and are factors to be considered in design for effective and efficient functioning of machines and equipment for material handling, processing and storage of agricultural granular materials.