MBEYA UNIVERSITY OF SCIENCE AND TECHNOLOGY
COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ENEGRY AND PRODUCTION ENGINEERING
MODULE NAME: PRODUCTION ENGINEERING
MODULE CODE: MEB 4106
LECTURER NAME:
DR. MTAWA
TASK: DESIGN PROJECT
TITLE: DESIGNING AND FABRICATION OF BEAN SHELLER
SUBMISSION DATE:
29/01/2019
COURSE: BACHELOR DEGREE IN MECHANICAL ENGINEERING (UQF 8)
S/NO
1
2
3
4
5
6
7
8
NAMES
SUMMARI EDWIN A
HASSANI M MOHAMED
SIAH STANSLAU
KELVINI ROMWALDI
ZUBERI KHAMIS
HAMISI MAZIGE
MWINYI HASSAN
LEODIGA MALKIORI
ADMISSION NUMBER
B31621041
B41521054
B31621040
B41521070
B41521111
B41521051
B31621013
B41521073
SIGNITURE
ABSTRACT
This project work is on the design and manufacturing Beans Sheller. This is the machine
designed to remove the outer shell of the beans in developing country like Tanzania is
mostly carried by using a hand threshing .Apart from using a lot of time to threshing
beans, using hand threshing and separation of beans is labor intensive and the time
consuming. Transporting before threshing is costly, time consuming and causes loos of
beans
during
the
process.
There are existing numbers of machine doing the same work but they have a lot of
drawbacks that make it not favorable to small farmers. The machine manufactured from
this project will minimize the drawbacks to the extent that it will keep in consideration all
farmers’ needs as per data collected. All weaknesses of the existing machine were used as
the challenges to make sure that this machine to be the best of all existing.
i
TABLE OF CONTENTS
ABSTRACT ..................................................................................................................................... i
CHAPTER ONE ............................................................................................................................. 1
1.0 INTRODUCTION .................................................................................................................... 1
1.2 DESIGNING AND FABRICATION OF BEAN SHELLER ................................................... 1
1.3 PROBLEM STATEMENT ....................................................................................................... 1
CHAPTER TWO ............................................................................................................................ 3
2.0 METHODOLOGY ................................................................................................................... 3
2.1 INTRODUCTION .................................................................................................................... 3
2.2 literature review ........................................................................................................................ 3
2.3 data collection ........................................................................................................................... 3
2.4. Analysis of data........................................................................................................................ 3
2.7 Selection of some standard parts............................................................................................... 4
2.9 Prototype testing ....................................................................................................................... 4
2.10 Instruments used for drawings ................................................................................................ 4
2.11 Design for manufacture and assembly (DFMA) ..................................................................... 4
2.12 Manufacturing of prototype .................................................................................................... 4
Beans ............................................................................................................................................... 4
There are various types of beans ..................................................................................................... 4
2.13 Data Analysis .......................................................................................................................... 5
2.14Criteria for Success .................................................................................................................. 5
2.15 User Requirements .................................................................................................................. 5
CHAPTER THREE ........................................................................................................................ 7
3.0 PRODUCT DESCRIPTION/SPECIFICATION ...................................................................... 7
ii
3.1 Product Detail Drawing ............................................................................................................ 7
3.3 Function of Product................................................................................................................... 9
CHAPTER FOUR ......................................................................................................................... 10
4.0 PRODUCTION OF THE PRODUCT .................................................................................... 10
4.1 Process Plan ............................................................................................................................ 10
4.2 Threshing Unit Detail Drawing .............................................................................................. 11
CHAPTER FIVE .......................................................................................................................... 21
5.0 PRODUCTION COST............................................................................................................ 21
5.1 Drawing of the Product ........................................................................................................... 21
ARCO PRODUCT’S COSTING REPORT 1.............................................................................. 22
CHAPTER SIX ............................................................................................................................. 24
6.0 CONCLUSION AND RECOMENDATION ......................................................................... 24
6.1 Conclusion .............................................................................................................................. 24
6.2 Recommendation .................................................................................................................... 25
BIBLIOGRAPHY/REFFERENCES ............................................................................................ 26
APPENDECIES ............................................................................................................................ 27
APPENDEX A: ............................................................................................................................. 27
APPENDEX: B ............................................................................................................................. 28
APPENDEX C .............................................................................................................................. 29
APPENDEX D .............................................................................................................................. 30
APPENDEX E .............................................................................................................................. 31
APPENDEX F .............................................................................................................................. 32
APPENDEX G .............................................................................................................................. 33
APPENDEX H .............................................................................................................................. 34
APPENDEX I ............................................................................................................................... 34
iii
The Best Alternative Criteria ........................................................................................................ 35
APPENDEX J: DESIGNING CALCULATION. ......................................................................... 37
iv
CHAPTER ONE
1.0 INTRODUCTION
1.2 DESIGNING AND FABRICATION OF BEAN SHELLER
Bean Sheller is a machine which is used for threshing and cleaning beans from stalk and
husks. In other word any process that removes the edible grain from the plant is considered as
threshing. Many crops (such as wheat, and grain legumes) leaves the combine or thresher ready
for using or processing, but others (such as oats, spelt, barley, and buckwheat) have hulls that need
to be removed before further processing, especially if they are used for human consumption.
The beans have been threshed using a log, usually the threshing is done in a flat surface the
threshing done by small scale farmers and cost them money, time and result in losses. The higher
cost are caused by hiring workers to thresh the beans, the separation process of the beans also take
long time .All these two factor makes the small scale farmers do not make profit from the beans
they sell .our design reflect on solving these existing problem for small scale farmers since the
presence machine is too large and have high cost which not affordable by most of small scale
farmers so this design focus on solving it.
The expected benefit of our design will increase the efficiency of the process and ensure
that cost is reduced during beans threshing by observing the best alternative in term of material
used and performance output. However the time will be saved to accomplish the task.
1.3 PROBLEM STATEMENT
For long time Beans threshing have been a time consuming, tedious (by using their energy
in all process to get beans) and mind cracking process especially to many small scale formers in
the country
However tradition shelling method(stick on bangs) do not support good beans, hand
shelling takes a lot of time even with some hand operated simple tools. Hand threshing and
separation of beans is labor intensive and time consuming .transporting before threshing is costly
and cause loss of beans during the process.
The existing machine is too large and cost to acquire for small scale farmers .A portable
beans Sheller will reduce processing time and cost, while improving ergonomics for small scale
1
farmers. The design consider increasing efficiency of the method used to remove beans from the
pod ,reduce safety risk, improve separation rate ,quality control and decreases loss of the losses.
This lead to the design and fabrication of portable beans Sheller which will save the time and
increase the efficiency of the process
2
CHAPTER TWO
2.0 METHODOLOGY
2.1 INTRODUCTION
This chapter describe about the methods and procedures that required to follow for the successful
completion of the design and manufacture beans Sheller the following procedures will be taken to
accomplish this designation
2.2 literature review
In this area, Literature Review gives an overview of the related topics or act as a stepping stone of
the project. It gives the information on the progress of the various types of the existing shelling
technology, existing machines and its mechanisms. This information is mainly obtained through
browsing various internet websites, reading related engineering books, through the information
obtained the gap is discovered so that further action can be taken to bridge the gap.
2.3 data collection
These are the information gathered from different sources concern with the project which are of
more importance in developing the project. From the main three method of collecting data;
collecting data by interviewing, observation and questionnaires, two methods were used to collect
data; interviewing and observation.
2.4. Analysis of data
The collected data were analyses so as to make sure that the design is correct and optimal
2.5 preparation of technical drawing
All technical drawing were prepared in details so as to help in manufacturing process of the
prototype
2.6 Designing of the project parts
The designed several parts of the project to be manufactured were; Sieve, Shaft with spike/bitters,
Top cover, Inlet hopper, beans discharge spout, pulley, hopper, and main frame, key.
3
2.7 Selection of some standard parts
Bolts and nuts, belt cover, motor, v-belt were selected.
2.8 Manufacturing of the project
The required material should be selected that can be used to manufacture and able to withstand the
load applied and the parts. The material used are mild steel
2.9 Prototype testing
This is about the demonstration of the design, it takes the design from the virtual, imaginary into
the physical world and prove something works and being tested.
2.10 Instruments used for drawings
Special computer programs such as auto-card, solid work are used in designing, detail drawings,
assembly drawings etc.
2.11 Design for manufacture and assembly (DFMA)
DFM involves designing for the easy of manufacture of a products constituent’s part. It is
concerned with selecting the most cost-effective materials and processes to be used in production,
and minimizing the complexity of the manufacturing operations.
DFA involves design for a products easy of assembly. It is concerned with reducing the product
assembly cost and minimizing the number of assembly operations.
2.12 Manufacturing of prototype
The prototype is manufactured as per designing and technical drawings of Project
Beans
Are the edible nutrias seed of various plants of legume family especially of the genus phaseolus
planted for human consumption as food.
There are various types of beans
Red beans, kidney beans, White beans, Pinto beans, Pink beans, Navy beans, Pole beans, Garbanzo
beans, Soy beans
Red beans or red speckled bean have 40g to55g and 7mm to 11mm width with10mm to 24mm
length
White kidney bean has 80g to100g
4
Carioca bean (khaki) have 20g to 25g
Others like kablacketi, mandaba and maini have 7mm to 11mm width with10mm to 24mm length
(measured)
To come up with solution moisture content of bean should be known, hire are generally moisture
content of different dry beans like red beans, kidney beans, white beans which range from 5.76%
to 17.8% (Source; https://images.search.yahoo.com/yhs/search)
2.13 Data Analysis
i. Analyzing the probable solution
ii.
Determination of the machine parameters
iii.
Making the drawings in the form of assembly and detail which will assist in manufacturing
of prototype
iv.
Testing the prototype of beans threshing machine
In order to come up with the design, the f data were collected from small farmers
2.14Criteria for Success
i. The design should be of low cost
ii.
The design should be food safe
iii. The design should efficiently separate threshed beans from its residuals and dust
iv. The design be able to process large quantity per short time
v.
The design must be ergonomically acceptable
vi. The design should be esthetically pleasing
vii. The design must be environmentally friendly
2.15 User Requirements
i. The product is of low cost
ii.
The product is food safe
iii. Easy to manufacture and assemble
iv. The product is efficient in separating threshed beans from dust residuals
v.
The product’s processing rate is high
5
vi. The product is easy to handle and operate
vii. The product is easy for maintenance
6
CHAPTER THREE
3.0 PRODUCT DESCRIPTION/SPECIFICATION
3.1 Product Detail Drawing
7
Table 3.1 Bill of Materials
PART DESCRIPTION
Material of hopper mild
steel,
size (2000×1000)mm for 1
pcs
Material of frame steel
angle bar size:
(2100×13×13)mm
Material of threshing unit
carbon steel 70beaters,
shaft length
1000mm×∅20mm, length
of drum with beaters:
600mm×∅80mm
Material of concave steel
size:
650mm×300mm
dimension
Material of threshing
cylinder cone is mild steel
size: (500×294×2)mm
Material
of
blower
assembly is mild steel size
644mm×403mm
Material of outlet is mild
steel size :
(999×800×2)mm
Material of sieve is steel
size: 500mm×500mm
Electrical motor 7kw
P/NO.
1
MANUFACTURE VENDORS UNIT PRICE
(ARCO) Atlantic ARCO
Sh.62000/=
rich company
QNTY PRICE
1
Sh.62000/=
2
ARCO
ARCO
Sh.5000/=
17
Sh.85000/=
3
ARCO
ARCO
Sh.45000/=
1
Shs.45000/=
4
ARCO
ARCO
Sh.23000/=
1
Sh.23000/=
5
ARCO
ARCO
Sh.35000/=
1
Sh.35000/=
6
ARCO
ARCO
Sh.25000/=
1
Sh.25000/=
7
ARCO
ARCO
Sh.30000/=
1
Sh.30000/=
8
ARCO
ARCO
Sh.15000/=
1
Sh.15000/=
9
Vybo electric
Ball bearing
10
SDVV
Pulley (v-belt pulley)
11
RAJENDRA
Kishen
Sh.450000/=
1
enterprises
ltd.
SETL(Spec Sh.12000/=
6
ialized
engineering
.T. Ltd.
Alibaba.co Sh.12000/=
4
m
Estimated cost
8
Sh.450000/=
Sh.72000/=
Sh.48000/=
Sh.890,000/=
3.3 Function of Product
i. Threshing - used to separate the grain from the crop and remove the grain from the straw
and allows only grain to pass through.
ii.
Winnowing – can be used automatically by using electric motor to blow through the grain
which allow the lighter substance to fly away leaving the heavier grain which fall.
iii.
Sieving – separate unwanted material small particle like stone and to get only beans without
the contamination of the product by foreign bodies.
iv.
Collect – this is the final step that makes collection of all beans after passing all step and
to get pure beans without contamination.
9
CHAPTER FOUR
4.0 PRODUCTION OF THE PRODUCT
4.1 Process Plan
The chosen part of machine in process plan is Threshing unit, since it determines the salient
function of the machine. Dehulling process (i.e. separation of beans from their pods) is done by
threshing unit. It consists of shaft, threshing cylinder, peg teeth and spiral. Manufacturing of
threshing unit involves machining processes, welding process and cutting process.
10
4.2 Threshing Unit Detail Drawing
11
Process Planning Sheet.
Part name: shaft
Number off: -
Material: - Solid Round Bar Mild steel
Part No: -
Blank size: - Ø22 x 1100 mm
Drawing No: Standard time: - 14 minutes
lathe
2.
Facing from
workshop
Ø22 x 1100 mm to Ø22 x
1000mm.
Feed/ rev = 0.15mm/ rev
Spindle speed= 86 rpm
cutting speed= 30 m/min
lathe
3.
Centering
workshop
4.
Turning from Ø22 x
1000 mm to Ø20 x 1000
mm
Feed/rev = 0.5mm/rev
Spindle speed = 350 rpm
Cutting speed = 30m/min
workshop
Set-up
time(min)
Cycle time
(min)
Machine used
workshop
Machining
time(min)
Department
Or Shop
Holding the workpiece
Jigs/Fixtures
Description of
operation
1.
Tool standard
Operation No
Time analysis
chucks
2
1
3
Facing
cutter
chucks
0.7
1
1.7
lathe
Lathe
center
center
1
1.5
2.5
lathe
Cutter
(carbide)
centers
5.7
1
6.7
12
Part name: threshing cylinder
Number off: -
Material: - flat sheet metal
Part No: -
Blank size: - 2000x1000x3mm
Drawing No: Standard time: -
Cutting
disc
2.
Rolling the sheet metal
Plate
bending
rolling
machine
rollers
3.
Cutting two disc plates of workshop
external Ø80mm and
internal Ø20+0.05mm
Oxyfuel
cutting
Oxy-fuel
torch
4.
Welding plates to the
cylinder
Welding
machine
workshop
workshop
13
Set-up
time(min)
Cycle time
(min)
Tool standard
grinder
Machining
time(min)
Machine used
Cutting the metal sheet to workshop
600x251x3mm
Jigs/Fixtures
Description of
operation
1.
Department
Or Shop
Operation No
Time analysis
Part name: Peg teeth
Number off: -
Material: - solid round bar mild steel
Part No: -
Blank size: - Ø10x2730 mm
Drawing No: Standard time:
Cutting 26 pieces of
Ø10x105mm
workshop
grinder
Bench
vice
Set-up
time(min)
Cycle time
(min)
2.
hacksaw
Machining
time(min)
workshop
Jigs/Fixtures
Department
Or Shop
Making distance to cut
Tool standard
Description of
operation
1.
Machine used
Operation No
Time analysis
Cutting
disc
Part name: spiral
Number off: -
Material: - flat sheet metal
Part No: -
Blank size: - 2000x1000x3mm
Drawing No: Standard time: -
Cutting
disc
Spiral plate
rolling
machine
Join all parts by welding to form threshing unit
14
Set-up
time(min)
Cycle time
(min)
grinder
Machining
time(min)
Rolling flat sheet to make workshop
spiral shape
workshop
Jigs/Fixtures
2.
Tool standard
Cut flat sheet to
1951x50x3mm.
Machine used
Description of
operation
1.
Department
Or Shop
Operation No
Time analysis
Shaft
Processing of the shaft from the blank to the finished part is by machining process, i.e. involves
centering, turning, milling, surface finishing. Blank material used is mild steel since has a high
resistance to breakage, rod Ø22 x 1100mm.
Machining process
Lathe machine

Holding work piece

Facing Ø22 x 1100mm to Ø22 x 1000mm

Centering

Turning Ø22 x 1000mm to Ø20 x 1000mm
15
Threshing cylinder
The blank shape is flat sheet metal 2000x1000x3mm cut to 600x251x3mm, material is mild steel.
Sheet metal is rolled in plate bending rolls then welded to form cylindrical shape Ø80x600mm,
two round shape Ø80x3mm external and internal hollow Ø20+0.05x3mm are welded (by arc
welding) to the cylinder.
16
Peg teeth
The blank shape is solid round bar Ø10x2730 mm, mild steel. Cutting 26 pieces each Ø10x105mm
using grinder with cutting disc.
17
18
Spiral
The blank shape is flat sheet metal 1951x50x3mm, mild steel. Rolled in spiral rolling machine
with 3 number of turns. Then welded to the threshing cylinder.
19
All parts mentioned above are welded to complete the threshing unit.
20
CHAPTER FIVE
5.0 PRODUCTION COST
5.1 Drawing of the Product
21
ARCO PRODUCT’S COSTING REPORT 1
ALTANTIC RICH COMPANY
(ARCO)
P.O. BOX
SALAAM
1621
DAR
ES
Estimate #:
2019-1-31
Request for estimate #:
2019-1-31
Company:
ARCO
Customer contact name:
EDDY MARK
Customer
information:
0653955260
contact
Estimate date:
29-DEC-2018
Fax No: +222 1231
www.arco.net.og.tz
TABLE 5.1: GENERAL INFORMATION
PRODUCT NAME: BEAN SHELLER
MACHINE
Date and time of 29-Dec-2018, 12:47:54pm
report
Total weight
313.8Kg
Total
stock 510Kg
weight
Quantity
to 1 products
produce
Estimated cost of TSH.890,000/=
Arbor press machine pictorial view
product
TABLE 5.2: COST BREAK DOWN
1.
Estimated cost of product
TSH 890,000/=
100%
2.
Purchased Parts
TSH. 474,000/=
0.53%
3.
Toolbox Parts
TSH. 0.0/=
4.
Labor cost
TSH. 68,500/=
0.077%
5
Transportation cost
TSH 20,000/=
0.022%
22
0%
TABLE 5.3: COMPONENT COST IMPACT
Components contributing to total product cost
S/N
MATERIAL
COST/PART
(TSH)
Hopper
Material of hopper mild Sh.62,000/=
steel,
size (2000×1000)mm for 1
pcs
Frame
Material of frame steel Sh.5,000/=
angle bar size:
(2100×13×13)mm
Threshing unit
Material of threshing unit Sh.45,000/=
carbon steel 70beaters,
shaft length
1000mm×∅20mm, length
of drum with beaters:
600mm×∅80mm
Concave
Material of concave steel Sh.23,000/=
size:
650mm×300mm
dimension
Threshing Cylinder Material of threshing Sh.35,000/=
cylinder cone is mild steel
cone
size: (500×294×2)mm
MANUFACURIN
G
COST/PART
(TSH)
7,500/=
TOTAL
COST
(TSH)
67,000/=
2,000/=
6500/=
3,200/=
48,200/=
2800/=
25,000/=
4,000/=
38,000/=
6
Blower Assembly
3,000/=
27,500/=
7
Outlet
3300/=
32,800/=
8
Sieve
Material
of
blower Sh.25,000/=
assembly is mild steel size
644mm×403mm
Material of outlet is mild Sh.30,000/=
steel size :
(999×800×2)mm
Material of sieve is steel Sh.15,000/=
size: 500mm×500mm
1400/=
16,400/=
9
Motor
Electrical motor 7kw
Sh.450,000/=
Standard
450,000/=
10
Bearing
Ball bearing
Sh.12,000/=
Standard
12000/=
11
Pulley
Pulley (v-belt pulley)
Sh.12,000/=
Standard
12000/=
717,400/=
68,500/=
785,900/=
1
2
3
4
5
COMPONENT/P
ART
CONFIGURATION
TOTAL
23
CHAPTER SIX
6.0 CONCLUSION AND RECOMENDATION
6.1 Conclusion
The design of Beans Sheller is completed. During the designing, different factors such as
compatibility, machine portability, complexity of the mechanisms, efficiency and the cost of
manufacturing the machine were properly analyzed from which the optimum design was selected.
Base on the optimum design selected, all parts of the machine were designed to contribute on
making beans Sheller. Different parts were designed involving calculations and other parts were
designed on basis of shape and size of machine so as to reach the optimal design of the machine.
Also some of the part like bearings, belt, and key were selected as per tables of standards; hence,
such parts were mathematically proved in accordance of specifications of engineering discipline.
Assessment of the product on:
i.
Use-The dried bean should be put in the hopper while the machine is switched on. As the
beans pods are hit by a spike teeth on the shaft against the ones on the concave they are
shelled and rolled down to the outlet where they finally collected with the container.
In order to evaluate the performance of this machine, a known quantity of dried harvested
beans were fed into the machine through the hopper. The machine shelling efficiency on
each shelling operation was computed as:
Shelling Efficiency=
Total bean shelled by machine
Total bean fed in machine
× 100
The efficiency was calculated to be 81.3% with a 100kg/hr capacity.
ii.
Repair- any activities which return the capability of a bean sheller that has failed to a level
of performance equal to a greater than that specified by its function but not greater than its
original maximum capability.
Maintenance-A goal of maintenance is to eliminate unnecessary or unplanned down time
due to failure .Also the objective of maintenance is to ensure the reliability and safety of
the machine.
24
To ensure good planning of maintenance activities as well as actual repair activities the
following data should be included:a) Specification-type of equipment, capacity, load, speed
b) Spare parts number and where to get them.
c) History of repair activities to find out the cause of break down and prevent the same
failure again for the future.
d) Vibration analysis measure-this is strong in detecting failures in high speed
rotating.
e) Electrical monitoring-regularly check all electrical components
.
iii.
Disposal and recycling
The body of the thresher is a recycled drum and the blades of the blade type thresher are
made of a small strips of metal that can be obtained from scrapes left over from other jobs
within the workshop that require flat bars. In case the blade type thresher is failed it is
possible to re-use various components such metal plates and the blades as well as mesh.
This would reduce the generation of waste from machine once its useful life is over.
6.2 Recommendation
In order to ensure a good performance the machine; extreme humidity of the beans must
be controlled, since the extreme humidity can cause the rust to the shellering chamber unit and the
sieve plate can clogged with very fine crushed particle thus reducing the discharge capacity. Feed
rate control must be ensured, motor size should be correct, maintenance in the threshing chamber
is needed even before and after operation e.g. cleaning and removing of the stacked cobs particles
within the chamber. The capacity of the corn cobs threshing machine can be increased by
increasing the size of threshing chamber, number of bitters, increasing the size of motor according
to the applied load and the discharge unit can be adjusted to accommodate the capacity of the
machine. Also parts such pulley and bearing must lubricated with a grease and preventive
maintenance to the other parts must be made after every use.
25
i.
BIBLIOGRAPHY/REFFERENCES
Alibaba(2016).com .corn cobs crushing
ii.
machine.http://www.alibaba.com,20/12/2016.
iii.
.ESAFF.(2003). Seeds and agriculture research Tanzania process
iv.
..F ,M.(2011). Investment in agriculture research in Tanzania
v.
. khum r S & gupta,JK 2005.machine design.” engineering materials and their
vi.
properties”, New Delhi.
vii.
meikle, m(1784),threshing and cleaning of beans grain
viii.
. phot ,r.(2016) local threshing methods.
ix.
. sheller, a.b(2016).www.agriculture machine.com.
x.
Sheller, B. M.(2016).www.french bourgeoning/ bamba machine
xi.
Wikipedia (2016)http:/wikpedia.org/wikcom,21/12/2016.
26
APPENDECIES
APPENDEX A:
27
APPENDEX: B
28
APPENDEX C
29
APPENDEX D
30
APPENDEX E
31
APPENDEX F
32
APPENDEX G
33
APPENDEX H
Local threshing methods (photo, Tukuyu Mbeya)
APPENDEX I
Selection of best alternative
i.
Alternative one – Peg tooth type of cylinder
ii.
Alternative two- Wire loop cylinder
iii. Alternative three- Hammer milling cylinder
34
The Best Alternative Criteria
So as to select a best solution among the alternatives, criteria for selection of solution need to be
established.
i.
Manufacturability
ii.
Functionability
iii.
Maintainability
iv.
Safety
v.
Cost
vi.
Efficiency
vii.
Material availability
viii.
Ergonomics
ix.
Aesthetics
x.
Environmental friendly
The following evaluation scale was used to each alternative against each of the criteria.
SCALE
RATE
Excellent
5
Very good
4
Good
3
Fairly
2
Poor
1
Table 1: Evaluation scale.
35
S/NO
Criteria
Weight %
1.
Manufacturability
07
2.
Functionability
20
3.
Maintainability
06
4.
Safety
15
5.
Cost
06
6.
Efficiency
15
7.
Material availability
10
8.
Ergonomics
05
9.
Aesthetics
09
10.
Environmental friendly
07
Total weight
100
Table 2: Weight criteria.
S/N
Criteria
Weight%
Alternative
01
Alternative
02
Alternative 03
Rate
Score
Rate
Score
Rate
Score
1.
Manufactubility
07
5
35
4
28
5
35
2.
Functionability
20
3
60
3
60
3
60
3.
Maintainability
06
5
30
4
24
4
40
4.
Safety
15
4
60
4
60
4
24
5.
Cost
06
4
24
2
12
2
30
6.
Efficiency
15
4
60
3
45
3
18
7.
Material availability
10
5
50
4
40
2
30
36
8.
Ergonomics
05
2
10
2
10
2
10
9.
Aesthetics
09
5
45
4
56
4
36
10.
Environmental friendly
07
4
28
4
28
3
21
TOTAL
100
402
363
304
Table 3: Weight/Decision matrix approach in evaluation alternatives.
In matrix chart, above, Alternative 01 score the highest point 402, so it the highest rated
alternative and most suitable design
APPENDEX J: DESIGNING CALCULATION.
Components of the Machine
The machine consists of the standard and manufactured components/parts as listed below: i) Parts to be manufactured
Sieve
Shaft with spike/bitters
Bearing
Top cover
Inlet hopper
Beans discharge spout
Pulley
Hopper
Main frame
Key
ii) Standard parts
Bolts and nuts
Belt cover
Motor
V-belt
37
Main Technical specifications
i.
Production capacity of the machine
ii.
Production quality
iii.
Design of the shaft
iv.
Design of the main frame of the machine
v.
Determination of overall dimensions of the machine
Production capacity of the machine
Production capacity of the machine is given in mass per time that is kg/h, this rate depends much
on the following parameters: Selection of the motor
Design of the shaft
Design of the hopper
Selection of the motor.
In order to have the required capacity of production, the best selection of the motor should be well
performed by considering the following factors: 1) Motor power
2) Motor efficiency (90%-99% is required)
3) Motor speed
4) The motor should survive the abuse of the surroundings in which it operates
Design of the shaft
Material carbon steel
Calculation of Torque
Now the torque on the main shaft on which is the larger puller is attached and the torque on the
motor to which smaller pulley is attached can be obtained from the expression below
P = T⍵…………………………………………………………………………………… (1.1)
⍵=
2πN
60
…………………………………………………………………………………… (1.2)
Where
P = Power (kW)
T = Torque (Nm)
𝜔 = Angular velocity (rad/sec)
38
N = Speed (rpm)
Torque on the main shaft
Take N = N2 = 750 rpm
P = 0.37 Kw
2πNT
60
60P
T=
2πN1
P=
T=
60 × 0.37KW
2 × π × 750
T = 47.10Nm
Torque on the main shaft (larger pulley) T is 47.10 Nm
Torque on the motor
Take N = N1 = 750 rpm
P = 0.37 kW
2πNT
60
60P
T=
2πN1
P=
T=
60 × 0.37KW
2 × π × 1450
T = 24.01Nm
Diameter of the shaft
Assuming τ = 42mpa
πd3 τ
16
T × 16
d3 =
π×τ
T=
d = 17.2mm
Design of beater

Material Carbon Steel with density of 7.86g/cm3

volume = πr2h
39

g = 9.81N/kg
Volume of beater
Volume = 𝛑 × 𝟏𝟐 × 𝟏𝟎
Volume = 31.43cm3
Mass of the beater =Density of carbon steel
Volume of beater
Volume = 𝛑 × 𝟏𝟐 × 𝟏𝟎
Volume = 31.43cm3
Mass of the beater =Density of carbon steel x Volume of beater/cylinder
M = ρ×v
M = 7.86×31.43
M = 276.804
M = 0.276kg
Assuming there are five (5) rows of beaters around the threshing drum and 14 beaters per row
Total number of beater = 5×14
Total number of Beater is 70
Weight = mass×gravitation force
W = mg
W = 19.32kg×9.81N/kg
W = 189.529N
Total weight of beater = 189.5 ≈ 190N
Bearing selection
In the selection of bearings, the following conditions were considered;

Effect of high starting torque.

Ability of bearings to withstand or absorb combination of radial and thrust loads.

Ability of bearings to carry high overload for short period.
Based on the above conditions, two suitable medium ball bearings of bore diameter 20mm were
selected to bear the load on the shaft that transmits power to the beater.
Determination of expected bearing life
By assuming that, the machine is working for 8 hours of service per day; then the recommended
bearing life is 20000 hours.[Bandar, 1994]. The bearing life is expressed as;
40
L=
60N1 Lh
106
…………………………………………………………………………… (1.3)
Where;
L = Bearing life (in million revolution)
N1 = Speed of rotation of the rotor (rpm)
Lh = Bearing life (hours)
L=
60 × 1000 × 20000
= 840million revolution
106
Design of the pulley
Material selected for the design of the pulley is cast iron. Consider the figure below;
Figure 1: Sketch of the driven pulley.
Power can be transmitted is 5.5Kw which is calculated from the shelling requirements. So
according to the V-belt standards [Khurmi R.S, Gupta, V-belt and Ropes drive, A text book of
machine design, 2005]

Minimum pitch diameter of the pulley D = 500mm

Pulley diameter of the large sheave D2 = 200mm

Top width of the V-belt = 38

Thickness of the V-belt = 23
Thickness of the pulley,
41
D
tp = D 3…………………………………………………………………………………. (1.4)
2
=
500
+ 3 = 5.5m
200
The outer diameter of the hub, dh is given by;
dh= 2 x 30 = 60mm
The length of the hub, Lb is given by;
Lb = 1.5
Lb = 1.5 x 30 = 45mm
Power required by the machine
From; v = wr
But; v is given as 3m/s
(r) Radius of pulley is 0.119m
(N) Speed in revolution per minutes
(T) Torque is 282.909Nm
2πrN
60
60V
N=
2πr
60 × 3
N=
2π × 0.119
V=
N = 240.73rpm
2πNT
60
2π × 240.73 × 282.99
Power =
60
Power =
Power = 7132.18W
We know that 1hp = 745.699W
7132.18W = 9.6
42
Determination of Belt Length
Figure 2: Determination of Belt Length
Radius of pulley 𝑅1 is 0.119m
Radius of the pulley 𝑅2 is 0.085m
Length of belt (L) =?
Tension on tight side 𝑇1 =?
Tension on slack side𝑇2 =?
Angle of lap 𝜃=?
Angle of contact at smaller pulley 𝛼 =?
The center distance of belt in use depends on the size of the two pulley and is given as
Xmax = 2(𝐷 +𝑑)
Where; D is 238mm and d is 170mm
Xmax = 2(238+170)
Xmax = 816𝑚𝑚
The center distance of belt between two pulley let say is 870mm according to the shape of the body
of the machine
Total Length of belt = π(r1 +r2)+2π+(r1 −r2)2/x
Total length = π(0.119+0.085)+2π+(0.119−0.085)2/0.87
43
L=2.07m =2074mm.
Angle of contact at smaller pulley
𝑟1− 𝑟2
𝛼 = sin−1 (
)
𝑥
0.119 − 0.085
𝛼 = sin−1 (
)
0.87
α = 2.23°
Angle of lap
ϴ = (180 − 2α) ×
π
180
ϴ = (180 − (2 × 2.23)) ×
π
180
ϴ = 3.064°
Design of the hopper feeding
The shape of the hopper is rectangular; the required material used to make the hopper is mild steel
sheet of 2mm thick. This selection is due to the fact that the recommended material to be used for
crushing process is mild steel which has good resistance to wear and tear capability, and it is easy
machinable
.
Figure 3: The sketch of the hopper feed.
Design of the frame
44
The frame is manufactured by using Angle line bar of high carbon steel with dimension of 40mm
x 40mm x 4mm. The height of the frame is 770mm.The joining of the different joints is by welding.
The physical layout of the frame and the manner of fabrication can be seen in the assemble
drawing, appendix M. The figure below is the isometric view of a frame.
Figure 4: Sketch of frame.
45