ABSTRACT
There is need for a hygienic processing of cassava. Prevalent condition in the commercial grating area of this staple food shows a susceptibility of food contamination. This project addresses the need for the development of a home scale cassava grater where the materials, the tuber s of cassava being grated can be properly monitored.
Some design considerations used in this project are; the machine should be efficient during use in the household as well as moveable (portable) and Safety or easily operated. Another problem considerations is that cassava Produces a large amount of cyanogenic glycosides so in selecting materials, for construction adequate care must be taken not to use materials that cannot degrade /corrode easily due to the acidic content in cassava. The malice component which is made from mild steel which consist of major parts namely, the mainframe which is constructed with angle iron which gives strength and rigidity o the war all matins, the hopper/s receptacle through which cassava is admitted into the machine for grating, the grating unit consist of the shaft, perforated mesh rolled sheet, circular disc and rival pins, the discharge unit which direct the flow of the grated cassava to astrrage pit or receptacle, and the electric motor which is made from cast iron and winding horse power of the machine . The capacity of the grater fabricated was 158kg/hr. the unit cost is #62,100 as against the #75,000 for the current grating unit in the market.
TABLE OF CONTENTS
Title Page i
Certification ii
Dedication iii
Acknowledgement iv
Abstract v
Table of Contents vi
List of Table x
List of Figures xii
CHAPTER ONE: INTRODUCTION
- Introduction 1
1.1Varieties of Cassava 1
1.2 Importance of
Cassava 2
1.3 Uses of Cassava 3
1.4 Methods of peeling
Cassava 4
1.4.1 Manual Method 5
1.4.2 Chemical Method 5
1.4.3 Steaming Method 6
1.4.4 Mechanical Method 6
1.5 Justification of
the Study 7
1.6 Aim and Objectives 8
1.6.1 Objective 8
1.7 Scope of study 8
CHAPTER TWO: LITERATURE REVIEW
2.1 Background to the
study 10
2.2 Economic Importance
of cassava product 14
2.3 Steps or Procedures
for Cassava Processing 15
2.3.1 Peeling 16
2.3.2 Washing 17
2.3.3 Grating 17
2.3.4 Dewatering/Dehydration 18
2.3.5 Fermentation 18
2.3.6 Frying 18
2.3.7 Sieving 19
2.4 Types of Cassava 19
2.4.1 Manual Grater 20
2.4.2 Mechanical Grater 21
2.5 Factors Affecting Grating Performance 23
2.5.1 Capacity of Grater 23
2.5.2 The Rate of Grating 23
2.5.3 Rough of the Grater Surface 24
2.5.4 Moisture of Cassava Tuber 24
CHAPTER THREE: MATERIALS AND METHODS
3.0 MATERIALS AND METHOD 26
3.1 Materials 26
3.1.1 Mild Steel 26
3.1.2 Stainless Steel 27
3.1.3 Alloy Rubber 28
3.1.4 Cast Iron 29
3.2 Description of Machine Parts
31
3.2.1 The Main Frame
31
3.2.2 The Hopper 31
3.2.3 The Grating Unit 31
3.2.4 Electric Motor and Pulley System 32
3.2.5 The Discharge Unit 32
3.3 Project Methodology 32
3.3.1 Machineries and Machining Processes 32
CHAPTER FOUR:
DESCRIPTION OF THE MACHINE AND ITS MAJOR COMPONENTS
4.0 Description of The Machine and its Major
Components 35
4.1 Cassava Grating Drawing 35
4.2 Shaft Design 40
4.3 Determination of the Bending Moment of each
point of loading 41
4.3.1 Force Exerted on Shaft 42
4.3.2 Reactions at the Bearings due to Vertical
Loading 44
4.3.3 Reactions at the Bearings due to Horizontal
Loading 46
4.3.4 Speed Transmission 48
4.3.5 Power Transmission 49
4.3.6 Belt Design 50
4.3.7 Determine of Centre Distance 50
4.3.8 Length of Belt 51
4.3.9 Angle of Contact on Driver Belt Sheave 51
4.4 Performance Evaluation 52
CHAPTER FIVE:
5.0 CONCLUSION AND RECOMMENDATION 58
5.1 Conclusion 58
5.2 Recommendation 58
References 60
LIST OF TABLES
Table 1: Materials used
in the constructing of cassava grater 30
Table 2: Indicating the
number of loading and time taken for each
loading in
order to evaluate performance of existing Machine 53
Table 3: Indicating the
number of loading and time taken for each
loading in order to evaluate performance
of existing machine 54
Table 4: Comparison of
the commercial and fabricated grater 55
Table 5: bill of
engineering materials and evaluation 57
LIST OF FIGURES
Figure 1: Isometric
Drawing 37
Figure 2: Front View
Elevation 38
Figure 3: AutoCAD
Drawing 39
Figure 4: Grafting Drum
40
Figure 4: Shaft Bending
Moment Determination 41
CHAPTER ONE
1.0 INTRODUCTION
Human generation need recipe of various varieties to get
energy to perform their daily activities and also to survive, then there is
need for consumption of energy giving food like yam, cassava. Cassava is
originated from latin America and was later introduced to Asia in the 17th
century and to Africa in about 1558, in Nigeria, cassava is mostly plant by
subsistence farmers, usually intercropped with vegetables, plantation crop,
yam, sweet potatoes, melon,beans, and maize etc. Cassava is propagated by
20-30cm long cutting of the tree stem, space between plants is usually 1-1.5m.
Intercropping with beans, maize, and other annual crops is produced in young
cassava plantations.
- Varieties
of Cassava
Cassava is classified as either sweet or bitter, like other
roots and tubers, both bitter and sweet varieties of cassava contain auto
nutritional factors and toxins with the bitter varieties containing much larger
amounts. They must be properly prepared before consumption, as improper
preparation of cassava can leave enough residual cyanide to cause acute cyanide
intoxication, goiters, and even ataxia or partial paralysis, (Fao, 2001)
The more toxic varieties
of cassava are a fall-back resource (a “food
security crop”)
in times of famine in some places. Farmers often prefer the bitter varieties
because they defer pests, animals and thieves.
1.2 Importance of Cassava
No continent depends as much on root and tuber crops in
feeding its population as does as Africa. Cassava, yams and sweet potatoes is
an important source of food in the tropics. The importance of cassava to many
Africans is epitomized in its name for the plant, e.g ege, paki, agble. The
production rate world-wide is positive for cassava over the last years, and the
production increase by 12.5% between 1988 and 1990 with Nigeria becoming the
largest cassava producer in the world.
(Bamiro, 2006)
Cassava and yams also occupy an important position in
Ghana,niger republic, Benin republic,Cameron agricultural economy and
contribute about 46% of the agricultural Gross Domestic product (GDP). Cassava
accounts for a daily intake of 30% in Ghana and is grown by meanly every farmer’s family. Cassava is the
most favoured among all Tuber crops and even all food crops by Ghanaian
consumers. ( Bamiro, 2007 )
1.3 Uses of Cassava
Cassava is a staple crop
and food source for millions of people in Nigeria, Ghana and other parts of
Africa. It has many uses in addition to producing nutrition to humans. The
leaves can be eaten as a vegetable or cooked as a soup. They can also be dried
as hay and given as feed stuff to animals for extra protein.
The tubers can be
processed into many things
- Cassava can be processed
into flour. The flour can be used to produce most of our local food and even foreign food.
- Cassava can be processed
into chips. Cassava chips can be used for animal feed.
- Cassava can be processed
into ethanol. The ethanol produced from cassava can be used as bio-fuel when
combined with additives.
- Cassava can be processed
into fructose. Fructose is used in industry for sweetening fizzy drinks.
- Cassava can be processed
into starch. The starch can be used in textiles industry.
Cassava is usually grown for human
consumption. Fufu is a traditional way to consume cassava. There are 14 steps
to the process making fufu including peeling grating and washing so its time
consuming and labour consuming. Garri is another traditional way of eating
cassava. The cassava is grated and put into porous sacks for the water to drain
out and for the cassava to ferment slightly.Amala is another way of consuming cassava
which includes fermentation,drying,grinding and sieving processes . Cassava
flour has been turned into variety of snack foods. You can purchase cassava
snack that are promoted as “healthy
snacking”
in the UK in a variety of flours.
1.4 Method of Peeling Cassava
There are several methods of peeling
cassava, which have been adopted. They include manual, chemical, steaming and
mechanical methods. Each has its own advantages and disadvantages
1.4.1 Manual Method
The manual method of peeling cassava is primitive and
cumbersome. It’s
unhygienic, time wasting and requires more time of producing small quantities.
Also, it’s
carried out by hand peeling of cassava using a sharp edged object like knife.
Advantages of manual
peeling
1. It require no money
2. No chemical involved
which may lead to poison when react with tuber
Disadvantages of manual
peeling
1. So cumbersome and slow
2. Doesn’t encourage peeling of large quantity.
DESIGN AND FABRICATION OF A PORTABLE CASSAVA GRATER
