Conceptual Design of Animal Feed Chopper with Medium Capacity

Agriculture is the backbone of Ethiopia economy directly or indirectly and most of its population is residing in rural areas. The majority of rural community is engaged in agricultural crop production, cattle farming and poultry production. To prepare feed for animals, the conventional feed cutting machines are intensively used which do not have friendly operation. Chopping of animal feed is considered as a labour intensive processing operation in animal production system. Traditionally, animal feed, especially crop residue are chopped manually by a sickle in the farms of Ethiopia. It is a labor intensive, less efficient and time consuming operation. Keeping in view, the drawbacks of the traditional chopping, this study has been carried out for the design animal feed chopper machine in order to reduce the above mentioned. Engine operated animal feed chopper has been designed for chopping of crop residue and hay. The machine was designed with the following main components: feeding hopper, feed roller, rotating blade, casing with fixed knives welded on it, a screen and stands. The machine was seated treatment based on the design concepts and designed up to capacity 300 kg /hr. This machine was design keeping in view its multifunctional operation like for the cutting of maize stacks, sorghum stack, agricultural crop biomass etc. The pro-vision was provided to run this machine at variable speeds for different jobs/applications and to achieve variability in particle sizes. The economic production of designed animal feed chopper machine was simple and its cost 10,618.45ETBirr.


INTRODUCTION
Ethiopia has higher livestock population than any other country in Africa. According to Alemayehu (2002), livestock production contributes up to 80% of farmers' income and about 20% of agricultural GDP in Ethiopia. Besides this, the increase in human population and decrease in land productivity results in the increase in demands for arable land. For this reason, scarcity of animal feed and inadequate grazing land are the major problems in the country. It is needless to say in Ethiopia, traditionally livestock are mainly dependent on natural pasture and crop residue. Therefore grazing is the common practice in the country. The grazing situation is exacerbated by the high density of cattle, with stocking rates of four times the recommended levels being reported in certain areas. This results in the decrease in livestock feed, both in quality and quantity, in the latter part of the dry season. Usually residues from cereals are the main sources of feed, but these are low in nutrient content, and have poor digestibility and palatability. For this reason, livestock tend to lose their weight, and this, in turn, leads to the decrease in market value, draft power output, disease resistance and amount of milk from milking cows. In recent years, many farmers are engaged in fattening activities because of the opening of some livestock commercial channels to other countries, and also there is a great demand for local consumption. Therefore this activity needs more attention to get a better return from the sector. In addition, in some parts of the country, there is a long dry season, while in the other part there is a bimodal rainfall pattern with two relatively short dry seasons. One of the options to overcome a feed shortage during these dry seasons is to preserve excess fodder grown in rainy season in the form of silage. In Ethiopia, fodder making has never become a common practice. This is because without chopping compacting the material is difficult; and chopping is done manually with hand tools and so it consumes more labor. Therefore, to make silage making attractive to farmers, chopping should be simple to apply and not too labor-intensive. In addition to assisting compaction during silage making, chopping has a great advantage in silage making to increase the surface area to volume ratio of fodder to facilitate the fermentation process by making free the cell juice and expelling the air. As stated above, farmers in Ethiopia use farm residues of cereals as a feed source during the dry season. This residue has low palatability; to increase the palatability, farmers in Ethiopia can practice manual chopping, but it is too labor intensive. Even though Ethiopia has a huge number of livestock population, the economic productivity is minimal than technically possible. Among the many factors which contribute to this low economic productivity, feed shortage is the one. Whether other factors are favorable or unfavorable for livestock production, the availability of feed greatly affects the livestock productivity. Therefore, to increase the productivity of livestock, there has to be a means to alleviate feed shortage during the latter part of the dry season. Silage making when fodder is in excess and chopping farm residues to use as a supplement of livestock feed are the options. But the non-availability of an attractive chopping mechanism, for farmers to make https://journals.e-palli.com/home/index.php/ajfst Am. J. Food. Sci. Technol. 1(1) 31-49, 2022 silage and chop farm residues, poses a challenge. Hence the objective of this project was to design of animal feed chopper with the capacity of 300 kg/hr to assist farmers in silage making and chopping farm residues to use as feed for livestock.

General objectives
> To design of animal feed chopper with the capacity of 300 kg/hr Specific objectives > To develop function structure component parts of the chopper > To prepare 3D and 2D drawing of the chopper > To prepare exploded drawing of chopper machine

MATERIALS AND METHODS Design procedure/Steps
This project study was carried out after studying different research reports. Both primary and secondary sources of information have been exploited to conduct the study. The design steps used for animal feed chopper were: > The gathering required information which is associated with agricultural operation for chopping systems.
> Lists of design requirement > The conceptual design of an appropriate system to meet their needs.
> Prepare the selection matrix for each concepts > Rank the concepts > Combine the concepts to make one product concept > Select one or more products concept > Using objective tree analysis, select one best product concept and analysis for each parts > Modeling (using Solid work).

Design Aspects
The main design aspects considered during chopper development were cost and complexity of fabrication, energy requirement, ergonomic factor, maintainability, material strength, kinematics and style. Considering these design aspects tangential feed type chopper (hammer mill), without blowing fan and conveyor, was selected for this project. The machine is based on the principles of hammer mill by which size reduction is accomplished by the cutting effects of rotating knives against small stationary knife plates welded in the casing. Since the knives are swinging there is less likelihood of risk even if hard inert material accidentally gets into the chopping chamber. Feed enters into the chamber from the top of the chopper, and size reduction is done by the rotating knives; and finally, the output is discharged from the bottom of the machine. The knives cut the stover and other residue until they become small enough to pass through the bottom screen. Fineness of chopping is controlled by the screen size. It is obvious that the smaller the screen size, the more work will be required to reduce the particles to the desired size. Generally, the technology is simple in construction and easy to manipulate, and the replacement of parts does not cost much.

Design Concept Concept generation
The concept generation process begins with a set of customers need and target specification and results in a set product concepts from which we make the final specification. Introducing low cost automation was to overcome problems with the current manual or traditional method. In this mechanism there are a numbers of uncertain chopping machines such as hand operated chop. The concept of the work is, > Observe the manual methods to identify the important process variables.
> Quantify the important method > Investigate all areas of automated forming. > Produce a specification for a low cost automated system.
> Refined design of the machine, as this plays a major role in rural area. The above considering point we can design the semi-automated machine which replace manual process.

Design Requirements
The system was more probably chosen search for by fulfilling the following general design requirement.
> Simplicity of technology > High efficiency with its capacity of 300kg/hr > Low maintenance and repair cost > Small in size to transport from place to place > Less number of component > More accurate system as possible > Safe and easy to operation > Low manufacturing cost > Easy to assemble and Maintainability and also power sources

Concept selection
Concept selection is process of evaluating concepts with respect to customers need and other criteria, comparing the relative strength and weakness of the concepts for further investigation, testing, or developing.

Option Selection of the concept
The following possible alternative options will have deal in the variant evaluation. After constructing the decision tree the system may follow the shaded region as follow. The selection was based on the availability source and simple system. The option selection of the concepts was: > High efficiency, Simplicity of technology and economy concept > Animal feed chopping techniques (traditional, manual and engine operated chopping system) and > Selection of power sources (A= Generator, B= Solar energy, C= Engine and D= Manual operation) > Power transmission system (V-Belt driving, gear driving , chain and sprocket)

Assessment of values and Determination of Overall Values
The values are expressed in points of use value analysis approaches by giving 1 for more important criterion and 0 for less important criterion in a given pair of criteria to be evaluated.

Weighting Evaluation Criteria of the objective tree
According to the weighting evaluation putting assigning of weighting factors for each criterion by overall "O" letters. Weighting evaluation based on the structure of the objective tree     Here as shown in the table, the maximum rating is 85.53 and hence concept variant C was selected as the best concept or alternative. Therefore Engine was the most appropriate power supply needed to operate animal feed chopping machine. The other concept variant take into consideration is power transmission system. Power is transmitted from the motor to elements of the machine by using mechanical devices such as belt, chain and gear. Denoting A= Belt drive, B= chain drive and C= driving by gear. From this decision matrix, the best concept The other concept variant take into consideration is feeding system. Denoting A= manual feeding, B= belt conveyor and C= gravity and vibration o Transmitting structure mainly consist of belt, gears, pulley Selection of motor consider the design requirements (capacity given 300kg/hr) From the literature survey known that the torque of the motor must be between 30-80Nm was sufficient for feed chopper. For this project the selected net torque 50Nm and speed requirement 240rpm. Therefore, the Power requirement for the animal feed chopper was calculated by the following formula.

Design and selection of pulley diameters
The pulleys used in the drive system were made of cast iron. Pulley diameters were selected based on the need to reduce the engine speed to the required one. The pulleys must be in perfect alignment in order to allow the belt to travel in a line normal to the pulley faces. The pulleys may be made of cast iron, cast steel or pressed steel, wood and paper. The cast materials should have good friction and wear characteristics. The pulleys made of pressed steel are lighter than cast pulleys, but in many cases, they have lower friction and may produce excessive wear (Sharma & Mukesh, 2010). In our case the pulleys are generally made of cast iron, because of their low cost. The rim is held in place by web from the central boss or by arms or spokes. The following equation was used to determine pulley diameters.

Design of hub
The hub of a pulley is one of the most important components part. It gives support to the spokes and the shaft. The diameter of the hub was calculated using following formula. The outside of the hub is given by Nisbett & Richard (2011).

Determination of belt contact angle
The belt contact angle is given by the following equation (Khurmi & Gupta, 2005).

Main frame
Main frame is generally consists of four legs and made up of angle iron .The whole machine was mounted over the legs. The minimum height of the stand is approximately 550mm from the ground level for easy feeding of the crop in standing posture of the user. All detail dimension was described under the appendix, only the isometric view was drawn in the below figure.

Design of shaft
This shaft made up of mild steel carbon which is use for fitting the pulley and transmitting the motion of the feeder roller through the worm and gear. The main shaft was strictly attached with the pulley in its center whereas the other end is supported on a block through bearings. The length and diameter of the main shaft was calculated below. The shafts were designed on the basis of strength rigidity and stiffness. In designing shafts of the basis of strength, the following cases may be considered that is the shaft will be designed by considering the following.

Feeding Roller
There are two feed rollers, upper feed roller and lower feed roller, present in the fodder chopper. These rollers are made up of cast iron and have teeth on its periphery. The chopped material was first feed to the rollers, which in turn grip the material and then it move forward to the cutting blade. The lower feed roller was fix while the upper feed roller is spring loaded which can move up and down depending upon the quantity of silage being fed.

Figure 9: 3D view chopper blade
Joints A joint is a rigid rod that allows the rod to bend in any direction, and is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges located close together, oriented at 90° to each other, connected by a cross shaft. Power was transmitted to the feeding roller with the help of gear system. Silage was entered through the hopper to feeding roller. Feeding roller moves the silage to the cutting head. Blades cut the silage into uniform small pieces and throw the final product outside the machine.

Measurements
The following items were measured and estimated during evaluating the forage chopper under the studied parameters:

Feed Chopper capacity
The theoretical capacity Tth, in ton per hour, was expressed by the following relationship T th =(ρ f ×A t ×L c ×λ k ×Ƞc)/(6×108 )….......(39) Where: T th = Theoretical capacity, kg/s; ρ f = Density of forage in the thereat, in kg/m3; A t = Thereat area, in cm2; L c = Theoretical length of cut in mm; λ k = Number of knives on cutterhead, and Ƞ c = Speed of cutter head, rpm.

Methods of manufacturing for each part and assembly
For constructing of products materials are needed. All these processes used in manufacturing concern for changing the ingots into usable products it includes as shaping processes, machining processes, metal forming processes, joining processes, surface finishing processes and processes effecting change in properties. Therefore, animal feed chopper was manufacturing by the following method given in tables below: Bending, welding and joining by bolt and nut

Estimation of production costs
In designing and manufacturing a technology, cost analysing is one important factor to assure the reliability and affordability of that technology. For a given system, the cost of a subsystem (performing one function) can be estimated from individual components or functional groups. These costs are added together to give the total system costs. The cost estimating technique starts from a set of engineering drawings for components of an assembly, and calculates the cost of each operation involved in component manufacturing, assembling and finishing. To minimize the cost of manufacturing processes, eliminating unnecessary operations has a great effect on it. This can be achieved through proper planning, following sequence of operation and grouping of individual operation or group of operations in succession. Grouping operations has the following advantages; Reduced fixed cost Reduced labour cost Less handling Reduced setup time Smaller in process inventory Depending on the types of manufacturing process, total cost of the designed machine was determined by considering the following. The main elements of cost analysis includes Direct material total cost Standard items cost Direct Labour cost Operation cost

Direct Material Total Cost
To determine the total cost of direct materials used in the manufacture of the animal feed chopper a material balance and flow sheet should be developed. Once the materials balances established, raw material prices must be assessed and identified. Therefore the materials and their current cost needed to manufacture the chopper were studied from the current markets.
Cost summary of the animal feed chopper without Engine

CONCLUSION AND RECOMMENDATION
Animal feed chopping machine was simple in construction as there is not so much complication in design. It is also important that velocity ratio can easily be determining measuring number of teeth on gears. The machine was designed in such a way that it was requiring minimum space to install. As the motor was placed inside the machine stand not outside the machine, the space was considerably saved. Frame and machine stand, it can be handled safely without injury. Blades were provided with double sharpening edges. The machine was provided with motor sliding arrangement and the cutting blades can be easily chopping by operator for sharpening purpose. Machine has reduced noise and weight due to gears arrangement and compact design. Machine has casters for portability. It is also noted that the optimum results could be obtained using a capacity of has 300kg/ hr chopping cutting rate. The overall dimensions of the designed animal feed chopper machine were 950mm in height, and 1042 mm in width. Economic production of designed animal feed chopper machine was simple and its costs 10,618.45 EBirr.
The following recommendation should be carried on: > The proposed animal feed chopper machine for feed should be fabricated and evaluation to complete the processing of feed production in small productive farms. > Testing of the designed animal feed chopping machine should be carried out in the actual field condition for small farms development.