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 American Journal of  
Food Science and Technology (AJFST)

Conceptual Design of  Animal Feed Chopper with Medium Capacity
Degefa Woyessa1*, Geta Kidanemariam2

Volume 1 Issue 1, Year 2022
ISSN: 2834-0086 (Online)

DOI: https://doi.org/10.54536/ajfst.v1i1.532
https://journals.e-palli.com/home/index.php/ajfst

Article Information ABSTRACT

Received: August 15, 2022

Accepted: August 28, 2022

Published: September 04, 2022

Agriculture is the backbone of  Ethiopia economy directly or indirectly and most of  its pop-
ulation 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 opera-
tion. 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.

Keywords

Design Concept, Animal 
Feed, Chopper, Silage 
Making 

1 Oromia Agricultural Research Institute, Asella Agricultural Engineering Research Center, Asella, Ethiopia
2 Bahir Dar University, Institute of  Technology, Bahir Dar, Ethiopia
* Corresponding author’s e-mail: degefawoyessa20007@gmail.com

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 

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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)

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Table 1: Selective system option
Required power Generator Solar energy Engine  Manual operation 
Chopping techniques Tradition method Manual method Engine method 
Power supply system Chain and sprocket Gear driving  V- Belt driving 
Feeding system Belt convey Manual feeding Gravity and vibration 

Functional structure

Figure 1: Functional structure

Evaluation of  Concept of  selection design criteria
Selection of  design criteria

Figure 2: Structure of  the objective Tree

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Table 2: Determination of  weighting factors of  the ending branches and Compiling
No End branches Sub weighting factor Overall weighting factor
1 O111 0.25 x 0.4 0.10
2 O1121 0.4x0.3x0.4 0.048
3 O1122 0.6 x 0.3 x 0.4 0.072
4 O113 0.45 x 0.3 x 0.4 0.054
5 O121 0.45 x 0.3 0.135
6 O122 0.55 x 0.3 0.165
7 O131 0.6 x 0.3 0.18
8 O132 0.4 x 0.3 0.12

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

Figure 3: Assignment of  weighting factor for each criterion

Table 3: Weighted and Un-weighted Overall Values Determination
Criteria 1 2 3 4 5 6 7 8 Un weighted Over all Weighted over all
1 - 1 1 0 1 0 1 0 4 4/28 (0.143 )
2 0 - 0 0 0 1 1 0 2 2/28 (0.071 )
3 0 1 - 0 0 1 0 0 2 2/28 (0.071 )
4 1 1 1 - 1 1 1 1 7 7/28 (0.25 )
5 0 1 1 0 - 0 1 1 4 4/28 (0.143 )
6 1 0 0 0 1 - 1 0 3 3/28 (0.107 )
7 0 0 1 0 0 0 - 0 1 1/28 (0.036) 
8 1 1 1 0 0 1 1 - 5 5/28 (0.179 )
Total 28 1

Un-weighted Overall Value was calculated by: Weighted

Comparing Concept Variants

Overall Value was calculated by

Table 4: Satisfaction for achieving the criteria in Percentage
Satisfaction (%) Description
100 Excellent, Complete satisfaction, objective satisfied in every aspect 
85 Very Good, Extensive satisfaction, objective satisfied in all of  important aspect 
70 Good, Considerable satisfaction, objective satisfied in the majority of  aspects 
50 Fair, Moderate satisfaction, a middle point bin complete and no satisfaction 
25 Bad, Minor satisfaction, objective satisfied in some but less than half  of  the aspect 
10 Failure, Minimal satisfaction ,objective satisfied to very small extent 
0 No satisfaction, objective is not satisfied in any aspect 

Showing concept variant result in decision matrix of  
chopping techniques 
Three animal feed chopping techniques are considered 

to chop maize stack, sorghum stack with different 
range of  output within the specified time according 
to their capacity. These concept variant are Traditional 

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feed chopping, Manual operated feed chopping and 
engine operated feed chopping machine. A = Traditional 
chopping, B= engine operated chopping machine and   
C= manual operated feed chopping.
From the table 4 the maximum value of  concept variant 
is 84.68 at B. Therefore Engine operated animal feed 
chopping machine was the final selection.
Power supply is one type of  the input needed to operate 
chopper machine. There are four concept variant are 

considered to chopping 300 kg/hr within different 
duration of  time according to capacity of  device to 
generate power. 
These concept variant are Generator, Solar energy, 
Electric motor and manually operated. Let denoting A= 
Generator, B= Solar energy, C= Engine/ motor and D= 
Manual operation. After the result of  overall satisfaction 
is known for each concept variant then making decision 
applied.

Table 5: Decision making matrix for feed chopping technique
Criteria alternative 1 2 3 4 5 6 7 8 Overall Satisfaction 
𝑜𝑤𝑣𝑖 0.143 0.071 0.071 0.25 0.143 0.107 0.036 0.179 
A % 25 70 25 10 80 70 70 20 

% ×Owvi 3.575 4.97 1.775 2.5 11.44 7.49 2.52 3.58 32.5 
B % 85 80 90 95 65 80 75 90 

% ×Owvi 12.15 5.68 6.39 23.75 9.3 8.56 2.7 16.11 84.68 
C % 80 85 60 75 85 85 50 80 

% ×Owvi 11.44 6.035 4.26 18.75 12.15 9.10 1.8 14.32 77.8

Table 6: Decision of  Matrix for selecting the best power supply devices
Criteria alternative 1 2 3 4 5 6 7 8 Overall 

Satisfaction 
Rank

𝑜𝑤𝑣𝑖 0.143 0.071 0.071 0.25 0.143 0.107 0.036 0.179 
A % 25 25 10 20 30 90 10 40 

% * Owvi 3.575 1.775 0.71 5 4.29 9.63 0.36 7.16 32.5    4th
B % 10 80 50 20 80 40 20 60 

% * Owvi 1.43 5.68 3.55 5 11.44 4.28 0.72 10.74 42.84  3rd
C % 80 95 80 90 85 85 100 80 

% * Owvi 11.44 6.745 5.68 22.5 12.155 9.095 3.6 14.32 85.535  1st
D % 60 80 75 80 75 60 75 70 

% * Owvi 8.58 5.68 5.325 20 10.725 6.42 2.7 12.53 71.96   2nd

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 

Table 7: Decision Matrix for selecting the best transmission system
Criteria alternative 1 2 3 4 5 6 7 8 Overall 

Satisfaction 
Rank

𝑜𝑤𝑣𝑖 0.143 0.071 0.071 0.25 0.143 0.107 0.036 0.179 
A % 95 90 75 65 85 75 70 80 

% * Owvi 13.58 6.39 5.32 16.25 12.15 8 2.52 14.32 78.55           1st
B % 70 60 60 70 60 65 70 90 

% * Owvi 10.01 4.26 4.26 17.5 8.58 6.95 2.52 16.11 70.19        2nd
C % 50 70 80 85 70 65 55 40 

% * Owvi 7.15 4.97 5.68 21.25 10.01 6.95 1.98 7.16 65.15         3rd
variant was concept A.  It was 78.55; therefore belt drive 
was chosen to transfer the power from Engine or motor 
to the parts of  the chopping machine.

The other concept variant take into consideration is 
feeding system. Denoting A= manual feeding, B= belt 
conveyor and C= gravity and vibration 

Table 8: Decision Matrix for selecting the best feeding system
Criteria alternative 1 2 3 4 5 6 7 8 Overall 

Satisfaction 
Rank

𝑜𝑤𝑣𝑖 0.143 0.071 0.071 0.25 0.143 0.107 0.036 0.179  
A % 95 90 75 65 85 75 70 80 

% * Owvi 13.58 6.39 5.32 16.25 12.15 8 2.52 14.32 78.55           1st
B % 70 60 60 70 60 65 70 90 

% * Owvi 10.01 4.26 4.26 17.5 8.58 6.95 2.52 16.11 70.23       2nd

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C % 50 70 80 85 70 65 55 40 
% * Owvi 7.15 4.97 5.68 21.25 10.01 6.95 1.98 7.16 64.15         3rd

From this decision matrix, the best concept variant was 
concept A.  It was 78.55; therefore manual feeding was 
chosen in terms to economic visibility of  the chopping.
 Design and Analysis of  Animal feed chopper
 Animal feed chopper was driven by motor and makes 
the driving of  main shaft by belt. Under the high-speed 
rotation with cutter making the feed become filiform 
and powder, the feeds will be outflow from the material 
outlet through outlet parts of  the chopper. Feed chopper 
are made up of  feeding part, Cutting and throwing part, 
transmitting part, and safety device, so it was reasonably 
structured safe and reliable.

o Feeding part is feed rollers.
o Cutting structure made up of  motion knife and 

locking bolt.
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.

p=(2π N T)/60………………………….(3)
Where, P = power, kW

            N= number of  revolution (rpm)
            T = torque, Nm
p =(2π ×240× 50)/60
    = 1.25 kW, therefore we have to select 2 
HP = 2×0.746 = 1.5 kW was sufficient

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).

D =1.50d + 25.0……………………….(7) 
Dh=1.5d+25
     =1.5×30+25
     =70mm

Where:
 D = outside diameter of  hub, mm
 d = diameter of  shaft, mm

The length, L, of  hub is given by Nisbett & Richard 
(2011)

L= (π × d)/2………………………… (8) 
L=π/2×d=π/2×30mm
    =47mm

Let us use two belts in order to increase the speed of  
the chopper and then we have two pairs of  pulleys. The 
speed of  the first pulley in the twice of  the second pulley, 
take assume N1 = 25.57rpm. Then, the speed ratio was 
calculated N1= 25.57 rpm, d1 = 180mm, d2 = 90mm
Then the speed of  the second pulley N2 can be found the 
following relation

N2/N1=d1/d2,N2=N1×d1/d2 =25.57×180/90=51.14rpm

Determination of  pulley weight
Circular shape was used in the construction of  the 
chopper pulley. The weight of  the pulley was calculated 
as follows.

AP=  (πd2)/4………………........…….(9)
       =(π×0.182)/4=0.025m2

Where, AP = area of  pulley material
             d  = Diameter of  pulley, m

The volume of  pulley material was computed using the 
following equations (ITSI-SU, 2011);

VP= AP  × t………………………(10)
     =0.025  × 0.0039m
      =9.92×10-5m3

Mass of  pulley material was computed using the following 
equations. The density of  cast iron pulley (ρ) = 7200kg/
m3  (ITSI-SU, 2011)

MP= Vp  × ρ………………………..…(11)
     =9.92×10-5m3×7200kg/m3 
     =0.714kg

Weight of  pulley material was  computed using the 
following equations (Gat,  1988)

 Wp= Mp× g……………………...…..(12)
Weight of  larger pulley, Wp1=Mp1×g=0.714kg×9.81m/s2 
=7.004N
Mass of  smaller pulley, Mp2=ρ×v=ρ×(πd2)/4×t=7200×(
π×0.092)/4×0.00345=0.158kg
Weight of  smaller pulley, Wp2=Mp2×g=0.158kg×9.81m/
s2 =1.55N

Determination of  torque transmitted by the pulley
A first drive cast iron pulley transmits 96.98W at 25.57rpm. 
The diameter of  largest pulley is 180mm and has smooth 
straight arms of  elliptical straight arms of  cross-section 
in which the major axis is twice the minor axis. Find the 
dimensions of  the arm if  the allowable bending stress is 

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15MPa. Mention the plane in which the major axis of  the 
arm should lie.
Let b1 = minor axis, and
      b2 = major axis = 2b1
Known that the torque transmitted by the pulley

T=(P×180)/2πN………………………(13)
=(96.98×180)/(2π×25.57)
=17456.4/160.58=108.7Nm

Maximum bending moment at the hub end,
M=2T/n
=(2×108.7N.m)/1=217.42Nm

And section modulus,
Z=π/32×b1 (b2)

2…………… …(14)
=π/32×b1×(2b1)

2

=π/32×4b1
3=(πb1

3)/8
Known that the bending stresses, σb

15=M/Z=(217.42×8×103)/(π×b1
3)=(1739.34×103)/

(π×b1
3 )

b1
3=(1739.34×103)/(15×π)=36.93×103mm3

b1=33.3mm
b2=2b1=2×3.33=66.6mm

A first driven cast iron pulley transmits 96.98watt at 
51.14rpm. The diameter of  this pulley was 90mm and 
has full arms of  elliptical straight arms of  cross-section 
in which the major axis is twice the minor axis. Find the 
dimensions of  the arm if  the allowable bending stress is 
15MPa. Mention the plane in which the major axis of  the 
arm should lie. 

σb=15Mpa=15 N/m2

Let b1 = minor axis, and
b2 = major axis = 2b1

Known that the torque transmitted by the pulley,
T=(P×90)/2πN=(96.98×90)/(2×π×51.14)=8728.2/3

21.16=27.18Nm
Maximum bending moment per arm at the hub end,
M=2T/n=(2×27.18)/1=27.18Nm
And section modulus,

Z=(π(b1)
3)/8………………………………(15)

Known that the bending stress,σb,
15=M/Z=(27.18×8×103)/(πb1

3)=(217.44×103)/(πb1
3 )

b1
3=(217.44×103)/(15×π)

       =4616.56mm3

b1=16.65mm             
Therefore,   2b1=2×16.65mm=33.3mm

Selection of  the drive belt
V-belt and pulley arrangements were used in this work to 
transmit power from the engine to the roller shaft. The 
main reasons for using the v-belt drive was its flexibility, 
simplicity, and low maintenance costs. Additionally, the 
v- belt has the ability to absorb shocks there by mitigating 
the effect of  vibratory forces (Khurmi & Gupta, 2005).

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

φ=sin-1 ( (R-r)/L)…………………….(16)
φ= sin-1( (180mm-90mm)/1203.13)
 =sin-1 (0.0748)
 =4.29°

The angles of  wrap for the smaller and larger pulleys are 
determined by the following equation:
α1=1802sin-1 ( (R-r)/L)…………… ..…..(17)

=180-2sin-1 ( (180mm-90mm)/1203.13)
=180-2sin-1 ( 0.0748)=171.42° 

α2=180+2sin-1 ( (R-r)/L)………………..(18)
=180+2sin-1 ( (180mm-90mm)/1203.13)
=180+2sin-1 ( 0.0748)=188.58°

Where: R = radius of  larger pulley, mm; 
r = radius of  smaller pulley, mm; 
α1 = angle of  wrap for the engine pulley, degree; 
α2 = angle of  wrap for the roller shaft pulley, degree; 
C = is the center distance between the two center 

pulleys. Therefore, by using the above equations the 
determined values of  φ, α1 and α2 were 4.290, 171.420 
and 188.580 respectively.

Determination of  belt length 
The length of  belt appropriate to drive the system was 
calculated using the equation given below by Shigley 
(2001). Assume the distance between driver pulley and 
driven pulley, 180mm according to frame structure. 
Center distance (C) of  driven pulleys was given by:

C = 90/2 + 225 + 90/2 = 387 mm
L=2C+π/2 (D1+D2 )+(D2-D1  )

2/4C………….(19)
L=π/2(90mm+180mm)+2×387mm+(180mm-

90mm)2/(4×387mm)
=423.9mm+774mm+5.23mm
=1203.13mm

Where:   L = belt length, m; 
              C = center distance between pulleys, m;
              D2 = pitch diameter of  driven pulley, m; 
              D1 = Pitch diameter of  driver pulley, m. 

Since the calculated length of  v belt is equal to 
the closest standard belt the exact center distance is 
also correct. Therefore, center distance was equal to 
387mm. Speed of  the belt was calculated by using the 
following equation as given by (Khurmi & Gupta, 2005).
V=1+(π×D1×N1)/60………………(20)

=1+(π×0.18m×25.57rpm)/60=1+0.24=1.24 m/s
Determination of  belt Tensions 
Power requirement for animal feed chopper was 1.5 kW. 
As losses in between pulley arrangement is considered, i.e., Figure 4: Chopper pulley 3D view

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such that belt pulley power transmission efficiency is 85-
95%. To determine tensions on the tight and slack sides 
of  the belt the following equations was used (Khurmi & 
Gupta, 2005). Calculate belt tension and width: Design 
a rubber v-belt to drive a machine with 96.98W at 25.57 
rpm and fitted with a pulley 180mm diameter.
Allowable stress for belt, σ=2.1Mpa=2.1×106  N⁄m2 

Density of  rubber,ρ=1000 kg⁄m3  = 1000 kg / m3

Angle  of  contact driver pulley, θ=165°=165×π/180=2.88rad
Coefficient of  friction between belt and pulley, μ=0.3
Power transmitted (P)
P=(T1-T2 )×V…………………………(21)
96.98w=(T1-T2)×1.24 m⁄s
T1-T2=96.98w/(1.24 m⁄s)=78.2N………….….(22)

We Know that,
2.3 logT1/T2 =μ×θ
                  =0.3×2.88=0.864rad
      logT1/T2 =0.3756rad 

T1/T2 =2.375N……………………………..(23)
From equations (22) and (23),

T1=135.1N
T2=56.87N

Let b= Width of  the belt in meters, and t = thickness of  
the belt in meters. Assuming thickness of  the belt, t= 10 
mm = 0.01 m, cross-sectional area of  the belt
               A=b×t=b×0.01=0.01bm2

The mass of  the belt per meter length,
m=Area×length×density
=0.01bm2×1.203m×1000 kg⁄(m3   =12.03bkg/m)

According to Khurmi & Gupta, 2005 torsional moment 
(Tr) due to single belt tensions was determined using the 
following equation.

Tc=m×V2…………………..………..…(24)
=12.03b(1.24)2=18.5bN

The maximum tension in the belt
  T=σmax×b×t………………………...(25)
             =2.1×106×b×0.01
            =21000bN 
And tension in the tight side of  belt (T2),

56.87N=T-TC
=21000bN-18.5bN
=20981.5bN

b=56.87N/20981.5N=0.0435m=43.5mm. Therefore, 
the standard width of  the belt b is 50 mm.
Where: Tc and T= the centrifugal and maximum tension 
of  the belts (N); 
T1 and T2 = tension in the tight and slack sides (N);

 σmax= maximum safe normal stress (N/mm2);
 m = mass per unit length of  belt (kg/m) and
 v = is speed of  belt (m/s). 

Feeding hopper design
Hopper, use as a feeding unit is part of  animal feed 
chopping machine that serves material cutting into the 
blade housing. The cutting material is fed manually 
through the hopper from the top side. Hopper or Feeding 
Trough is used to feed fodder such as maize stack, cutting 
grass etc.  Hopper decides capacity of  feed cutter. The 

main purpose of  hopper is providing direction to fodder 
and bring contact with cutting blade. The hoppers 
house the materials and deliver the materials to the feed 
roller at regulated feed rate. The hopper has a shape 
which facilitates loading, maximum volume utilization 
and reliable and complete gravity discharge through its 
outlet. The volume of  the hopper was calculated by the 
following equation:

V=h/2 (A1+A2+√(A1 A2 ))………...(26)
A1=354 mm×152mm
=53,808mm2

A2=270 mm×98mm
=26,460mm2

V=460mm/2(53,808mm2+26,460mm2+√(53,808
〖mm2×26,460mm2 ))
V=0.00143m^3
Where, V= volume of  hopper, mm3, h = height, (460mm)
A1 = base area of  truncated cone, top of  hopper, mm2
A2 = base area of  truncated cone, bottom of  hopper, 
mm2

Determination weight of  feeding hopper 
Trapezoidal shape was used in the construction of  the 
animal feeding hopper. The weight was calculated as 
follows. Mass of  
feeding hopper material was computed using the 
following equations (ITSI-SU, 2011)

MF= AF  ×t ×ρf…………………….(27)
MF=0.08  m2×1.5×10-3 m×7850kg/m3

MF= 0.945 kg
Weight of  feeding material was computed using the 
following equations (Gat, 1988)

 WF= Mf  ×  g………………………(28)
      =0.945 kg ×9.81m/s2  
      =9.272 N 

Figure 5: Feeding Hopper 3D view

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.

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Figure 6: Main frame 3D views (all dimension in mm)

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.

Shaft subjected to a twisting moment 
To find the diameter of  the shaft when the shaft was 
subjecting moment (torque) only
T/J=τ/r………………….......…………(29)
Where: T = Twisting moment or torque acting on the 
shaft. 

J = Polar moment of  inertia of  the shaft about the axis 
of  rotation.

τ = Torsional shear stress and 
r = Diametric distance from neutral axis to the outer 

most fiber.
The allowable shear stress for the shaft material was 
calculated as 

τ=σu/2fs……………………………...(30)
=560Mpa/(2*3.5)

=560Mpa/7=80Mpa
Where, σu=560Mpa for carbon steel
            fs = factor of  safety 3.5
From the equation 

T=π/16 τ*d3……………………….(31)  
The diameter of  the shaft by considering twisting of  the 
shaft 

T=π/16×τ×d3=50000Nmm=π/16*80*d3,
d3=(50000*16)/(80*π),d=14.27mm

Shaft subjected to bending moment   
When the shaft is subjected to bending moment only, 
then the maximum stress was given by

M/I=σb/y……………………………(32)
Where   

M = bending moment 
I = moment of  inertia of  cross sectional of  shaft
σb = bending stress 
y = distance from neutral axis to the outer most fiber

For round solid shaft, moment of  inertia is found by
I=π/64*d4 and y=d/2   substitution in equation (32) 

M=π/32*σb*d3…………………….(33)
The maximum bending moment of  the carbon steel was, 

M = 424320Nmm. Substituting the above values to 
determine diameter of  the shaft

M=π/32*σb*d3   
424320Nmm=π/32*160Mpa*d3

d3=(424320*32)/(π*160)=27013.05,
d=27013.05=30mm

Therefore,  for the design we should have to taking the 
maximum of  the two 30mm > 14.27mm, the diameter of  
the shaft was , d = 30mm.
Mass of  shaft was calculated by the following equation

M=ρ*v…………………………….(34) 
Shaft made up of  carbon steel with density of  7853kg/
m3.

V=A*L=(πd2)/4*L
   =(π*(0.03)2*0.7)/4
   =4.95×10-4m3

Mass of  shaft  material was computed using the following 
equations (Gat, 1988)

MS   = 4.95×10-4m3× 7850kg/m3

        =3.885 kg
The weight of  the shaft was estimated using the following 
equations 
    Ws  =Ms×g
    Ws  =3.885 kg×9.81 m/s2

          =38.12 N

Figure 7: Design of  chopper shaft 

Design of  Gear
The gears are used to transmit power .By changing the 
gear used; the speed can be adjusted to obtain various 
cutting lengths. These gears are used to transmit the 

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power from main shaft to feeding rollers. Assume that the 
speed of  lower roller was = 55 rpm Let power transmitted 
= 1.5 Kw. Let take input out- put = 240 rpm
Out -put speed =55 rpm 
The gear was made from hard steel material having 
ultimate bending stresses (σut=700 N/mm2), Number of  
teeth on gears was calculated by the following formula.

T2/T1 =N1/N2 …………………….……(35) 
T2=N1/N2 ×T1
T2=240/55×T1, Assume, T1=16 teeth,   T2=240/55×16
=70 teeth

Figure 8: Design of  3D view of  Gear

Chopper Blade
These blades are made up of  High carbon steel or alloy 
steel. The function of  the blade is to cut the silage 
material that can be chopped into smaller pieces suitable 
for animal feed. There are four cutting blades used in this 
machine

Figure 9: 3D view chopper blade

Estimation of  Force required in cutting chopper blade 
Estimation of  Force required in cutting chopper blade 
was calculated by the following formula (Khope & 
Modak., 2013)

F=A×NS×S……….....................……….(36)
Where, F = force required in cutting the silage
            A = cross section area of  individual stem
            NS = number of  stem at a time in throat
            S = shear strength of  material

Housing/upper cover
Housing covers the cutting sharp edge. Housing 
protects the person from not touching the cutting edges 
accidentally.

Figure 10: 3D view housing or upper cover

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.

Figure 12: 3D view UCP bearing or joint

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Chopper rotor with its assembly 
These are made up of  hard metal steel plates. These 
rotor acts as the rotating member of  the silage cutting 
mechanism

Figure 13: 3D view chopper rotor with assembly

Working Principle of  animal feed chopper 
Engine drives the main shaft with the help of  belt drive. 
Gears, Pulleys and blades are mounted on the main shaft. 
Main shaft drives the blade and gears mounted on it. 
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:

Theoretical and actual lengths of  cut
The theoretical lengths of  cut Lth was calculated using 
the following equation according to (Telang, 2016;  
Sankpal et al., 2017).

Lth=(60000Vf)/(λk n_c )……………….……(37)
Where:

Lth = Length of  cut, cm
Vf  = Feed velocity, m/s (peripheral speed of  feeding 

mechanism);
nc = Cutter head rotational speed, rpm, and
λk = Number of  knives on the cutter head.

Cutting efficiency
The cutting efficiency of  the animal feed chopping was 

calculated as follows
Ƞc=Lth/Lac ×100…………………….(38)

Where,       
Ƞc  = Cutting efficiency, %
Lac = Actual length, (mm) and
Lth = Theoretical length, (mm).

Feed Chopper capacity
The theoretical capacity Tth, in ton per hour, was 
expressed by the following relationship
Tth=(ρf×At×Lc×λk×Ƞc)/(6×108 )….......(39)
Where:

Tth = Theoretical capacity, kg/s;
ρf  = Density of  forage in the thereat, in kg/m3;
At = Thereat area, in cm2;
Lc = Theoretical length of  cut in mm;
λk = Number of  knives on cutterhead, and
Ƞc= Speed of  cutter head, rpm.

Cad Drawing Of  The Parts And Its Assembly

Figure 14: Inlet 

Figure 15: Inlet top cover

Figure 16: Bolt and nut

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Figure 17: Feeding hopper/inlet assembly

Figure 18: Hinge flange

Figure 19: Hinge pin

Figure 20: Outlet

Figure 21: Enclosure main side panels

Figure 22: Enclosure main front inlet panels

Figure 23: Electronic enclosure

Figure 24: Guard mount

Figure 25: Electronic enclosure mount

Figure 20: Main assembly of  animal feed chopper with 
pulley guard

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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:

S. 
no

Components Methods of  manufacturing 
pats

1 Main Shaft facing,Grinding, boring and  
turning

2 Feeding hopper  Bending, welding and joining
3 Feed Rolls Casting, rolling and shaping
4 Housing/upper 

cover
Bending, drilling and joining

5 Feed roll Shaft Rolling, grinding and slotting
6 Gears Grooving, Casting  and shaping
7 Pulley Shaping, Rolling and 

machining 
8 Chopper Blade Grinding, shaping, punching 

and drilling 
9 Main Frame Sawing, drilling, cutting, welding 

and joining 
10 Chopper rotor Shaping, rolling,
11 Pulley guard Bending, drilling and joining by 

bolt and nut
12 Hinge flap Rolling 
13 Engine setting Joining by bolt and nut and drilling 
14 Outlet Bending, welding and joining 

by bolt and nut

Table 9: Technical Specifications of  animal feed chopper
S. no Type Specification
1 Number of  Gear 02
2 Number of  rollers 02
3 Number of  blades 04
4 Width   chopper 1042 mm
5 Height chopper 950 mm 
6 Capacity 300 kg/hr
7 Approx. Weight 120 kg 
8 Engine speed 240 rpm
9 Types of  belt used V-Belt drive
10 Feeding hopper Length 450 mm,   

Width 250mm, 
Height 235 mm

11                                     Frame 550 mm in long, 430 mm 
in wide

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

Table 9.1: Cost summary of  the animal feed chopper 
without Engine
1 2 3 4 5 6

Ra
w

 m
at

er
ia

l c
os

t 
(B

irr
 )

M
at

er
ia

l 
w

as
ta

ge
 

2.
5 

%
 o

f 
1 

( B
irr

 )

M
ac

hi
ne

  c
os

t 
(B

irr
)

 L
ab

or
 c

os
t (

Bi
rr

)

O
ve

r- 
he

ad
 c

os
t 

%
  5

 o
f 

3 
&

 4

Pr
od

uc
tio

n 
co

st
 

(1
+

2+
3+

4+
5)

 
Bi

rr

10,136.8 253.42 27.37 190 10.868 10,618.450

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 

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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.

REFERENCES
Gat, U. (1988). The weight of  mass and the mess of  

weight.In Richard Alan Strehlow. Standardization of  

Technical Terminology, Principles and Practice:ASTM 
International, 2, 45-48.

ITSI-SU, J. 26, (2011). Mass, volume and density of  regularly 
and irregularly shaped object. Internet:< http://www. 
pdesas. org/module/content/resources/14756/view. 
ashx.

Khope, P.B., & Modak, J.P. (2013). Design of  
experimentation for establishing empirical relationship 
of  chaff  cutting phenomenon energized by human 
powered flywheel motor

Nisbett, R. G. B., & Richard, J. K. (2011). Shigley’s 
Mechanical Engineering Design. (9th edition), McGraw-
Hill, New York, USA.

Khurmi, R.S., & Gupta, J. K. (2005). A textbook of  
Machine Design, 4th edition,Eurasia publishing 
house (PVT.) LTD. Ram nagar,New dellhi,India.

Sankpal, N., Powar, V., Patil, S., Salunke, K., & Pandit, P. 
S. V. (2017). Design and Modification of  Chaff  Cutter 
Objectives : International Journal of  Innovative Research in 
Science,Engineering and Technology, 5675–5683.

Sharma & Mukesh. (2010). Farm Machinery Design 
Principles and Problems.1st Edition,Jain Brothers 
16/873, East Park Road, Karol Bagh, New Delhi.

Telang, A.K., 2016. Design and Modal Formulation of  
Power Operated Chaff  Cutter. International Journal on 
Emerging Technologies (IJET), 4, 0975-8364.

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APPENDIX

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