Design and Development of a Petrol-Powered Hammer Mill Machine

A conventional hammer mill is a device consisting of a rotating head with free- swinging hammers, which reduce rock, grains or similarly hard objects to a predetermined size through a perforated screen. Hammer mills can be used for grinding laterite sand in its not-so-fine form into a finer/smaller form for sand production for the building/housing sector. This project is focused on the design, development, and testing of a hammer mill that has a small scale production capability for usage by small and medium scale (SME’s). The grinding process is achieved by the use of a hammer in beating the material fed into fine particles; the fineness aimed depends on the detachable screen with aperture sizes ranging from 87µm to 2 mm. The conceptual design was based on the principle of design by analysis. The methodology adopted was to examine the most critical defects of conventional hammer mills and provide solutions. The major components of the new hammer mill are Inlet tray, Throat, Magnetic chamber, Rotor, Crushing chamber, Hammer mill body, Hammers/Beaters, Screen, Bearings, Discharge, Table or stand, Mechanical drive, Pulleys, The simple aim of this paper is to develop a hammer mill machine that will enhance the efficient grinding operation of laterite rock into a sandy profile to be used in the construction/housing sector. This paper presents the design of an efficient hammer mill machine that was developed with locally sourced materials with ease of maintenance amongst other advantages. The machine is driven by an electric motor of 7.5kW at a speed of 1440rpm and with the appropriate pulley ratio, the machine operated at a speed of 4320RPM with an operating rate of 250kg/hour. Several fabrication techniques such as welding, machining, etc. are adopted for the fabrication of the machine. Dry rocky laterite sample was tested with the machine for operational effectiveness and the result shows that the machine has a grinding capacity of 250kg/hr and grinding efficiency 0f 98.2%. The fabricated laterite grinding machine performed well with high sieving efficiency, reliability, durability with an estimated cost of 965,000.00 Nigerian Naira. 
The study was carried out in Akure, Ondo State, Nigeria. A performance evaluation was carried out on the machine and the grinding efficiency of 94.4% was achieved.