American Journal of Mechanical Engineering, 2016, Vol. 4, No. 3, 108-111 Available online at http://pubs.sciepub.com/ajme/4/3/4 © Science and Education Publishing DOI:10.12691/ajme-4-3-4 Design, Fabrication and Testing of a Wet Legume Dehulling Machine Egbe E.A.P. * , Roland B.O. Department of Mechanical Engineering, School of Engineering and Engineering Technology, Federal University of Technology, Minna, Nigeria *Corresponding author: evus.egbe@gmail.com Abstract The traditional method of dehulling legumes such as cowpea, soya beans and locust beans is by rubbing the seeds between the palms or by pounding in mortar but this process consumes time and energy. A motorized wet type legume dehuller was designed and fabricated to de-hull soaked seeds. It was designed to work on the principle of compression for the splitting of the soaked seed coat. The de-hulling is achieved by shear and friction between the beans coat and the wall of the de-hulling chamber. The device was designed and fabricated using locally available materials and technology. The motorized legume de-huller operates at effective de-hulling speed of 438 rpm and achieved a maximum efficiency of 95.2% for 6 minutes soaking period for cowpea, 72.2% efficiency for soya beans soaked in hot water for 30 minutes and 62.5% efficiency for 15 hours cooking period for locust beans, The de-huller was designed for feed rate of 500 seeds per second. Keywords: legume, dehulling, abrasive, strength, soaking period Cite This Article: Egbe E.A.P., and Roland B.O., “Design, Fabrication and Testing of a Wet Legume Dehulling Machine.” American Journal of Mechanical Engineering, vol. 4, no. 3 (2016): 108-111. doi: 10.12691/ajme-4-3-4. 1. Introduction Legume is an important food item (because of its high protein and fat contents) in Nigeria and most West African countries [1]. Dehulled cowpea is required in the preparation of some table meals (fried beans cake-akara, boiled cake-moimoi). In spite of the widespread use of beans as a staple food among Nigerians, the dehulling of beans is carried out manually. The operation generally requires soaking the cowpeas in water for 2 to 10 minutes [2] draining and rubbing between the palms, or beating with wooden pestle and mortar. Housewives and food vendors carry out these operations daily [3]. A knowledge of mechanical properties of grains, such as hardness and compressive strength are vital to engineers handling agricultural products. Hardness is defined as the ability of a material to resist indentation or abrasion. This property is required for the design of agricultural processing equipment to minimize breakage and wastage. Abrasive strength is the force requird to remove or protect the very tight coated membrane on grains such as cowpea seeds. Chukwu & Sunmonu [4] submitted that the mean compressive strength, tensile strength, abrasive strength, shear strength and torsion strength of Sampea 7 cowpea are 66.25 N, 65.53 N, 64.55 N, 65.20 N and 65.00 N, respectively and for Tvx 3236 cowpea are respectively 93.65 N, 93.55 N, 92.56 N, 93.50N and 92.75 N. 2. Materials and Method All the materials used for different parts of the machine were locally sourced. Galvanized iron sheet was used for the hopper; due to its corrosion resisting properties. Plain carbon steel was used for the shaft due its moderate ductility and malleability which improves its workability and it is widely available and obtained at a cheaper price compared to other alloy steels. The choice of 1×1×1.5mm mild steel square pipe, for the frame, was influenced by its availability and cost of purchase compared to an angle iron. Galvanized steel pipe was used for the dehulling chamber. A thick galvanized steel sheet was used for the auger majorly because of its ability to resist rust formation on the surface which can contaminate the food substance being dehulled. A 1.5 mm thick galvanized steel sheet was used for frame cover due to its high malleability and ductility which makes it easy to be folded and joined. Alloyed steel pulley was used due to its rigidity and its availability. 2.1. Determination of the Striping Torque of Different Cultivars of Cowpea Two cultivars of cowpea were considered for this design, Sampea 7 and Tvx3236. The abrasive force is denoted by F a . Therefore dehulling/striping torque required is given by: a g T F D = × (1) where g D geometric mean diameter of the seed. = The approximate abrasive forces required to dehull cowpea Tvx 3236 and sampea 7, at a feed rate of 20 seeds per minute was given as 92.56N and 64.55N, by Chukwu and Sumonu, [4]. The average abrasive force for feed rate of 500 seeds per second was deduced to be 1571.1N for