Design of a Cassava grating machine which has two modes of operation was made. It can be powered either electrically or manually. It takes care of power failure problems, and can be used in rural settlements where electricity supply is not in existence. Cassava is fed with the Machine through the hopper made of metal sheet to the granting drum, which rotates at a constant speed. This process grates the cassava into cassava pulp. The chute constructed of metal sheet accepts the pulp and send it out because of its inclination which operated manually, the efficiency of the machine was found to be 92.4%, which the efficiency of the electrically powered machine was found to be 91.9%.
Cassava is a major source of carbohydrates in human diet, being processed into Garri, fatal and typical as a constituent for human food. Recently other areas of uses of cassava are being implored. It is also being used as starch. The crop tolerance makes it more popular and now replacing yam in some part of Nigeria. The sweet varieties could be boiled for human consumption.
The tubers of cassava cannot be stored longer after harvest before decaying, and so processing follows immediately after harvesting. Cassava processing leading t size reduction includes peeling, grating dehydrating, milling and sieving. A typical cassava processing plant should therefore consist of units produced to achieve all the stages or steps mentioned above. The aim of this paper is therefore to present the result of efforts made in producing a device that is used in granting. The transformation of cassava tubers into pulp form is called grating.
Traditional tools used in Garri processing includes: Millstone, grinding stone, pestle and mortar. In these methods have low productivities and low hygienic solution to these problems that led to the designing and construction of machines that can grate the cassava of high quality in a short period of time and reduce human drudgery. Some of the machines include: roller crushing mill, hammer mill, bar mill, grater etc, all having one problem or the other.
Oyesola (1981) reported that, the traditional method of grating involves placing of the local grater, which is made of perforated metal sheet on the table where it is convenient for effective use and brushes sheet metal. The cassava turns into pulp and drop into container that is being used to collect the grated pulp cassava.
Adejumo (1995) in his design used a wooden grater in which the cassava forced into a hopper is rubbed against the grater which is being electrically power. Enhanced quantity of cassava can be grated using this method. However the durability of grater is low because of its wooden nature.
Ndaliman (2006) described a pedal operated cassava grinder which is powered by human efforts applied to pedal. The grinder pulverizes the cassava tubers into paste which can pass through a wine sieve. The effective performance of the design was at 60%.
The current design consists basically of 3 units: the hopper unit, the grating drum and the delivery channel. All these components are mounted on an angle iron frame. The machine assembly is powered mechanically or manually incase of electricity failure. It can be use in rural settlements where electricity supply might not in existence. Apart from faster rating rate, it required less him involvement. The grating drum is made of metallic pipe that carries a perforated plate which served as the grater. This overcomes the problem faced in the wooden grating drum.
Design Analysis and Calculations
The general consideration in designing this dual – operational grating machine is producing a machine that can be easily assembled or disassembled, a machine in which the hopper allows materials to pass through effectively with minimum wastage; the grating drum is made of metal so as to increase its durability; the chute is sloppy to allow grating pulp to slide downward and get discharge by gravity.