Abstract:
The development of machines to handle the process of producing adequate aggregates for the construction of structures for handling agricultural materials is far from expected in the area of farm structures in Nigeria. A Jaw crusher was designed and fabricated using locally available materials. The crusher consists of the following components namely; the hopper, jaws, adjuster, shaft and collector. The machine is powered by a 20hp three-phase electric motor with 1490rpm and driven on three type B-92 belt. Granite boulder samples were collected from a stone blasting site in Obanla area of the Federal University of Technology Akure and prepared to an approximate size ranging between 20mm × 100 mm × 80 mm and 25 mm ×180 mm × 6mm as feed materials, the choice of the feed size was dependent on the hopper design. These materials were fed into the machine at various speeds using pulley to vary the speed and the results obtained were analyzed to determine the performance of the machine. A predetermined mass of boulder was subjected to crushing and the subsequent outputs recovered from the chute of the machine. A uniform feed of 100kg was introduced into the machine; and the machine was run for ninety seconds (90s) and the products were analyzed using the sieves i.e. (25.4mm+) and (53mm+). A minimum mass of 0.82kg was lost at machine speed of 498rpm and a maximum mass of 12.1 kg was lost at a machine speed of 798rpm. The minimum sizes recovered were 6mm-2mm and the maximum recovered was about 58mm.The losses in materials were within negligible ranges till the machine speed of 638rpm was attained. It was observed that the optimum speed of the machine was found to be 638 rpm, the capacities ranges from 3.1 ton/hr. to 4 ton/hr. and this categorizes the crusher under small scale crusher. A total functional efficiency of 85.48% and machine quality of performance of 65.71% was achieved. A conclusion was reached that the nature of the aggregate output shape depends on the initial feed size, amount of force delivered to the boulders and the machine speed. It was however recommended that the machine clearance adjuster be made functional and effective to further increase the machine quality of performance. The total cost of production of the machine was found to be Eight Hundred and Twenty Seven Thousand, Seven hundred naira only.
