Development and performance evaluation of a die and Roller Pelleting machine.
Pelleting is a process whereby several ingredients such as fishmeal, maize, methionines and some crushed grain materials are compacted and forced out through die opening by mechanical process (Nasi and Calni, 2005). This normally involves heat, moisture and pressure. Heat and moisture breakdown and soften the components such as proteins and carbohydrates making them easier to mode and compact together (Walker, 2001: Walker and Raven, 2000). The pellet is formed in various ranges and shapes depending on the die.
Food for pets, poultry, fish, chicks, can be pelletized. Also fertilizer, drugs as well as wood in powdery form can also be pelletized for the ease of handling (Plavnik and Hurwitz, 1989; Barraza et al., 1991 and Milstein et al., 2008).
There are many reasons why pelletized feed is preferred
* Ease of handling
* Improvement of feed efficiencies
There are two types of pellet; Soft type pellets and hard type pellets. Production of pellet meal is available in a wide range of sizes from 0.1mm-6mm or more depending on the size and age of the animal.
To determine the appropriate size of pellet, these factors are needed to be considered
* Type of formulation,
* Capacity requirements and
* Pellet quality requirements.
* Size and age of animal
Materials and Methods
Design of the Die and Roller pelleting Machine Factors considered in the design and fabrications of the pelleting machine are
* Availability and cost of materials required,
* Corrosion-resistance ability of the materials,
* Mechanical and chemical properties of the materials considered.
The materials use in the fabrications is majorly Mild Steel and High Carbon Steel because of their strength and availability.
Basic considerations were given to the design for the size/dimension and capacity of the components, including the belt pulley system, the speed of operation, machine power rating of shaft and bearings. The major components of the machine are the frame, hopper, pelleting die, rollers and discharge sprout. The machine is powered by a 3kW, 960rpm three-phase electric motor.
Brief description of the machine
The livestock feed pelleting machine is made up of Hopper, Shaft, pelleting Die, pelleting Roller, Electric motor, Pulley, Casing/Stand, Discharge Sprout and roller adjusters and bearing.
Casing/stand: The casing which also functions as stand for the machine is made of iron sheet of 1mm thickness. It houses the belt and the pulley and also guides the operator against accident from sudden removal of the belt and the key.
Electric motor: The electric motor with power rating of 4 horse power/3KW powers the engine. It is important to note that the engine can also be powered by a 2horse power rated electric motor, but factor of safety was put into consideration in the choice of the 4horse power electric motor incase of any extra load.
The hopper: The hopper was made up of 1mm mild steel having thickness of 2.5mm with a cylindrical base, and rod round its edge with length 250mm and breadth 290mm while the circular hollow is 80mm. It is shown in plate1.
The pelleting rollers: The roller is made of low carbon steel cut like a gear. It is held by a shaft also made from mild steel. The choice of the material is to avoid wearing of the gear teeth due to the rubbing action between the die and the roller.
The Shafts: There are two shafts both made of mild steel. It was design in a way that it will be able to withstand stress. The tensional rigidity was also put into consideration.
The roller adjusters with bearings: This is also made from mild steel. It is used to adjust the roller. It is shown below (Plate 2)
The pelleting die: The pelleting die as shown in Plate 3 is made from perforated mild steel with 137 dies of 6mm in diameter each. It is removable.
Operational procedure: A livestock feed obtained from Adom Agro Allied Nig. Ltd. Ogbomosho, Oyo State, Nigeria was thoroughly mixed with selected binder that is water, or vegetable oil as the test required. The blended mixture is then poured into the running pelletizing machine hopper. The electric motor transmits a rotary motion to the die and rollers in the pelleting machine and the roller compressed the materials to the die and force the mixed feed out of the die as a pellet.
The material used for the evaluation test include an electronic digital weighing scale, weighing bowls, an electronic oven, drying pans, a note pad for recording data and result. The feed ingredient used was purchased from Adom Agro Allied Nig. Ltd. Ogbomosho, Oyo State, Nigeria and mixed manually to get homogenous feed.
Evaluation of the efficiency of the machine was carried out using 2 different binders (water and vegetable oil).The specimen preparation and mixing ratio was as shown in Table 1. A specific quantity of feed is choosing and this is constant throughout the trials and the quantity of binder used is also noted and recorded. After the ground form of the livestock feed has been thoroughly and homogenously mixed with binder i.e. water or vegetable oil as desired for testing, the mixture is then poured into the machine and the output produced, percentage pellet, percentage crumbled and percentage of 6mm pellets produced are estimated.
To calculate the efficiency of the output produced
The percentage quantities of the pellet were determined by using the formula below;
% output pelletized = weigth of pellet produced/weigth of total feed x 100% (1)
Determination of the efficiency of the machine
The percentage quantities of the 6mm\(6mm die was used for the test) pellet were determined by using the formula below;
% output 6mm pellet = weigth of 6mm pellet produced/weigth of total feed x 100 (2)
Determining the percentage crumbled feed
The percentage quantities of the crumbled feed were determined by using the formula below;
% crumbled 6mm pellet = weigth of crumbled produced/weigth of total feed x 100% (3)
Determination of percentage of binder to be added
The percentage quantities of binder were determined by using the formula below;
% quantity of binder = weigth of binder measured/weigth of feed sample x 100% (4)
Results and Discussion
The results of the analyses carried out on the machine were as shown in Table 1. It was observed that there were significance differences in the pelleting efficiency, production efficiency and size efficiency of the machine due to type and quantity of binder. Example of pellet produced is shown in Plate 1.
The production efficiency was increased from 70% to 82.4% when water was reduced from 34% to 25.9%. This shows that a reduction in water as a binding agent increased the production efficiency in the range considered (Fig.1). The regression equation for relationship between the weight of water as binder and the production efficiency of the pellet machine is as shown in Equation 5.
[FIGURE 1 OMITTED]
[Eff.sub.p] =[0.015Ww.sup.2] - 0.085Ww + 0.37 (5)
It was also observed that an increase in water as binder reduces the pelletting efficiency of the machine (Fig.2); this may be due to a reduction in cohesion between the particles of the feed as the moisture increased. The regression equation for relationship between the weight of water as binder and the pelleting efficiency of the pellet machine is as shown in Equation 6.
[Eff.sub.p] = [1.37Ww.sup.2] - 5.98Ww + 100.7 (6)
[FIGURE 2 OMITTED]
The inclusion of vegetable oil as binder has a visible change in the production efficiency from 50.6%, to 88.90% when ratio of vegetable oil to water was increased from 0.20:0.03 to 0.20:0.05 (Fig.3). As the ratio of the vegetable oil inclusion as binder is increasing the production efficiency is also increasing. Although, the resulting efficiency is lesser compare with when water only is used as binder. The pelletting efficiency was found to be 96.95% when water alone was used as binder (Fig.4). From the results, it was observed that water as a binder produce the highest efficiency both in pelleting and production efficiency of the machine. In conclusion, it is hoped that production of this portable and affordable pelleting machine will ease the availability of feed to small and medium farmers.
[FIGURE 3 OMITTED]
[FIGURE 4 OMITTED]
We appreciate Engineer Akeem Ibrahim of AK-bratney Agro allied Ltd. Alagbado, Lagos, for his technical assistance during the construction of the machine.
 Barraza, M. L, Coppock C.E, Brooks K.N, Wilks, D.L , Saunders ,R.G and Latimer G.W(jr) . (1991): Iron Sulfate and free pelleting to Detoxify free. Gossypal in cotton seed diet of dairy cattle. Journal of Dairy science. Vol. 74 (10) Pg 3457-3467.
 Milstien, A, Alkon ,A, Karplus ,I. Kochba ,M, Avnimelech ,Y (2008). Combined effects of fertilization rate manufacturing and feed pellet application on fish performance and water quality in polyculture ponds. Aquaculture Research, 26 (1), Pg 55-65.
 Plavnik, K and Hurwitz, S (1989): .Effect of dietry protein energy and feed pelleting on the response of chicks to early feed restriction. Poultry science. Vol.68(8), pg1118-1125.
 Nasi and Calini, (2005); Survey of food processing retrieved march 11, 2009 from, http = //www, fao.com.
 Walker, G. and Raven, P., (2000); Livestock feed processing, Western Farmer's Association Seminar seatle, Washington, USA.
 Walker, G. (2001); Food Processing, Western farmer's Association Seminar, Seatle, Washington.
Idowu D.O. *, Abegunrin T.P., Adejumobi M.A., Adebayo J.M., Akinleye P.A. and Fadele F.
Department of Agricultural Engineering, Ladoke Akintola University of Technology, P.M.B. 4000, Ogbomoso, Oyo State, Nigeria
Corresponding Author E-mail: email@example.com