Development and evaluation of hand operated seed cleaner for small-holder farmers in East Hararghe, Oromia

Cleaning and grading are two fi nal operations of high-quality grain production that are traditional method cleaning & separation of sorghum and maize. Farmers normally do by hand which have many problems. The farmers of East and West Hararghe Zones have a problem of high seed shortage to get improved seed at the right sowing time and du to absent of cleaning &separation machine to use local seed of good variety. To reduce the problem the hand operated seed cleaner machine horizontally vibrating air-screen type was designed, fabricated and its performance was evaluated with the main parts of centrifugal blower, eccentric unit & a set of reciprocating sieve with belt-pulley driven system. The machine separates product on the basis of the differences in their sizes and incorporate fan to remove light particles. The machine was constructed at the FARC workshop from locally available materials. The machine was tested for its cleaning effi ciency & capacity with sorghum & maize at Damota arada and observed that, the maximum cleaning effi ciency of the machine at moisture content of 18% & 19 were 80 % for sorghum and & 90 % for Maize, and its capacity was found 5.7 & 8.5 q/hr for sorghum & maize respectively, which is much better than that of traditional cleaning which have observed about 0.8 & 1.2 q/h for sorghum & maize respectively. During the test seeds of others crop & seeds of weeds were found below the range which is 300 & 200 unit/kg respectively. The newly developed low production cost machine has got a promising acceptance for its higher effi ciency, higher capacity and lower lab our time energy requirement and accessibility to be used both for seed cleaning, grading and commercial use, and also due to its simplicity and locally manufactured, it showed a potential for wider adoption, as a result, experiments and/or demonstrations will be continued under the local Hararghe under farmers’ conditions. Research Article Development and evaluation of hand operated seed cleaner for small-holder farmers in East Hararghe, Oromia Teshome Urge Jiru1* and Ibsa Aliyi Usmane2 1Oromia Agricultural Research Institute, Fadis Agricultural Research Center, P. O. Box 904, Harar, Ethiopia 2School of Rural Development and Agricultural Innovation, Haramaya University, P.O.Box 138 Dire Dawa, Ethiopia Received: 12 March, 2021 Accepted: 01 May, 2021 Published: 05 May, 2021 *Corresponding author: Teshome Urge Jiru, Oromia Agricultural Research Institute, Fadis Agricultural Research Center, P. O. Box 904, Harar, Ethiopia, Tel: +256667549; Fax: +0256667551; Email:

accesses to use their produced product seed of good quality of local good varieties [3].
These postharvest losses can be minimized signifi cantly with primary processing [4]. Cleaning and grading of agricultural commodities are considered as most important primary unit operations. In design of effi cient and effective cleaning and grading machines, physical properties of materials are taken into account [5]. There are quite a number of factors that affect the performance in terms of cleanliness and grain loss during the operation. Such factors include amount of wind or air velocity, feed rate, and shaker frequency, dimension of sieve opening, sieve tilt angle, crop variety and moisture content [6]. Portable cleaning & grading machine need to reduce the improved seed shortage problems faced by farmers of eastern & western Haraghe zones thus the primary needs of our smallholder farmers for high quality seed grain and improved seed or commercial seed products a hand operated seed grain cleaner & grading machine was developed and evaluated. Therefore, it is clear that there is a great initiation for new ideas and novel approaches to meet these requirements that can be used on farm level & within the purchase power of farmers will help that, a hand operated air screen seed grain cleaning & grading machine was designed developed and performance evaluation made on, sorghum and maize grain seed, to strengthen seed shortage problem the to stimulate agricultural production by obtaining additional market by meeting export demands, & minimize the wide gap of technological different used by developed countries and in general the productivity of farmers will be increased.

Objectives
 To design & develop hand operated seed grain cleaning and grading machine.
 To evaluate the performance of developed hand operated seed grain cleaning and grading machine

Materials and Methods
The following steps were considered during the design of machine:-physical properties ,terminal velocity, coeffi cient of frication, the arithmetic mean diameter of grain stroke length by [7] (1) & homograph or calculating board by [7] (2) energy requirement from ergonomic data by (7 [D] (3) of machine velocity ratio by [8] was found. The width is necessary to reduce bed thickness, and the length to allow the undersize to be removed without inordinate amount of fi nes in the oversize. So that the size of screen was decided by considering the general rule that the length of screen should be between 2 -3 times of its width (1).

Design considerations
ii. Shape of the opening: the shape of screen opening depends up on the shape of grain to be handled. There for, for rounded shaped grain, the top screen of round holes and bottom screen of slotted holes were used for sorghum and for maize both rounded holes screens were used.
iii. Percentage open (perforated) area: Higher percentage open are increase both capacity and screening effi ciency.
To ensure good contact and maximum available use of plate area, holes were spaced as close as practicable; nevertheless, it was done that by recognizing that there was a great limitation to increase the open area.
Excessive loading in terms of strength means excessive cost of replacement which might be more than the saving resulting from increased capacity (1).
iv. .A aperture size: For round openings, the size of scalping screen was decided to be slightly higher than the equivalent diameter of the grain to pass through the aperture, & whereas size of grading screen was kept small enough to retain the smallest desirable grain.
v. Angle of inclination: Both screens where made adjustable to different degrees of inclination with horizontal plan.
The common range in pith adjustable is from 4-12 0 [8] (1). To obtain optimum capacity and effi ciency, it was decided to use 12 0 for scalper and 8 0 for grading

Centrifugal Blower
Fan selection calculation depends upon terminal velocity of maize and sorghum where adopted by [7,9]

1.
The rotational speed of driver pulley, rpm   1 1   n nc Sc (1) Where, nc S c -0.051 factor

2.
Determine the rotational torque on input shaft from ergonomic data by (8) 0.08 (kW) Where T-Torque in put shaft P 1 =The average output manpower of adults men from ( 0.8) KW W 1 = angular speed at input shaft 1000x0.8/170 = 4.7

6.
Find the angular speed of the driven shaft 150/51.8 =2.9

Calculation of centrifugal Fan
Calculation of centrifugal agricultural blower by academic [11,12] The outer diameter of blower was calculated (1) The outer diameter of blower was calculated:

The working principles of machine
The product inters the machine through feeding hopper baffl e plate with different opining size dropped on upper sieve in the sieve box. When materials to be separated. are put on vibratory screen, because of its vibration, materials are also agitated during their transit over the screen Impurities of larger size stubbles, chaff etc are retained on the top sieve & discharged out through over size outlet. When grain & small particles falls from upper sieve to second sieve , light materials are blown away by blower. Impurities including shrived grain, stone, soil, dust and other small materials which have weight & smaller diameter than second sieve were separated by the second sieve & passed through the second sieve & dropped on the pan, discharge out through under size out let. Clean grain was retained on second sieve & discharged out from the machine through clean grain outlet.

Performance evaluation
The performance evaluation of the design developed hand operated seed grain cleaning and grading machine was conducted using two type of seed grain i.e.-sorghum and maize. For test the machines was taken to Haramaya district in specifi c place known as Bate 04 Arada. In the cores of undertaking the fi eld performance of machine human characteristics, size, weight, age, health, environmental factor & crop condition were considered. For fi eld testing three levels of blower speeds were obtained by changing driven pulley sizes, three stroke length by adjusting bolt and three feed rates for each grain were used. For each observation the mean of the three replications were taken for each test run, a known weight of grain was feed at a time & the cleaning time for each test run was recorded by a stop watch. The sample grain was collected at all out let (sieve over fl ow, under size, clean grain and blower) out let Table 2.
The moisture contents of grain was determined using the universal moisture tester i Dole 400Model was used & the moisture was found 18.%, 19 % for sorghum and maize respectively, then the moisture contents of grain during threw test period has not shown change, so the moisture content of grain during the test were kept constant. For this testing purpose Maize and sorghum that had been threshed by thresher were used. The evaluation of cleaning effi ciency stander metallic round sieve of hole Φ 12 & Φ 6.3 mm for upper & bottom sieve were arranged. Sieve box was made from a chip wood and covered with Formica to make its surfaces smooth and water proof resistance The Sieve box was tightening to supporting frame by four hanging shoe. All the outlets were mad on the sieve box. Crank mechanism with adjustable crank length and connecting rod to achieve various levels of reciprocating amplitudes was employed to drive the shaker.
Supporting frames made of rectangular pipe by welding and Where E = fraction of clean seed at clean seed outlet(%); F = fraction of clean seed in feed, (%) G = fraction of clean seed at foreign mater outlet (%) The capacity of machine was calculated by obtained clean grain from clean grain outlet per unit time [in second] or output product rate in second multiplied by 3600 expressed in Kg/h [1].

Results and discussion
The design developed hand operated seed grain cleaning and grading machine the average output of grain cleaner for sorghum were varied from 4.  Table 3.

Conclusions and recommendations
The overall performance of the developed machine was satisfactory that is output capacity of developed grain cleaner & grading machine was ranged from 4.