DESIGN AND FABRICATION OF A PORTABLE CASSAVA GRATER
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
Table of Contents vi
List of Table x
List of Figures xii
CHAPTER ONE: INTRODUCTION
1.0 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
2.0 Literature Review 10
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
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
5.0 CONCLUSION AND RECOMMENDATION 58
5.1 Conclusion 58
5.2 Recommendation 58
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.
1.1 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
i. Cassava can be processed into flour. The flour can be used to produce most of our local food and even foreign food.
ii. Cassava can be processed into chips. Cassava chips can be used for animal feed.
iii. Cassava can be processed into ethanol. The ethanol produced from cassava can be used as bio-fuel when combined with additives.
iv. Cassava can be processed into fructose. Fructose is used in industry for sweetening fizzy drinks.
v. 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.
1.4.2 Chemical Method
Chemical method is often adopted in the industries, factories and food processing companies. It involves chemical actions and thermal shock which leads to weaken and loosening of the skin using caustic soda (NaOH).
The disadvantages of this method of peeling cassava include;
⦁ Cost of acquiring caustic soda.
⦁ The difficulty in controlling the penetration of chemical in the cassava tuber.
⦁ The difficulty in the removal of chemical traces as it may be poisonous.
⦁ it is easy and encourage large quantity peeling
⦁ it required little human effort.
1.4.3 Steaming Method
The tubers are subjected to high steam pressure over a short period of time to avoid partial cooking (or eventual cooking). The disadvantage is that the tubers could be subjected beyond the time.
1.4.4 Mechanical Method
This includes mechanized means of peeling, aimed at peeling a large number or a batch at a time. Many mechanisms have been devised for this purpose, this includes the continue process, abrasive belt conveyors and batch abrasion types among others.
These methods of peeling have not been yielded the desired results. Hence, the continued research in this area. An extensive literature research was conducted to determine the state of the art in cassava processing.
1.5 Justification of Study
Presently in Nigeria, the products of cassava are usually locally consumed and exportation is low due to reason that the products do not always meet the international standards for healthy foods. Thus, the need to encourage the small scale(home production) of cassava product to ensure quality of products and good hygienic values.
From the research carry out, it was discovered that most of the cassava graters machines in the research area are usually corroding (reducing service life) due to the acidic nature of the cassava fluid and materials used for the fabrication. To ensure all cassava products is free from any taste, odour, or infected by iron content of parts (food poisoning) which may affect the quality of their contents (Giews, 2001) hence need to modify the design and use appropriate materials for fabrication.
Now, the government has also started campaign for production of bread using cassava flour to reduce more concentration on wheat.
1.6 Aim and objectives
The sole aim of this project is to design and fabricate improved cassava grating machine.
1.6.1 Objectives:The objectives of this project are as follow:
i. To modify the design of the existing cassava grater (dimensions) to the home use-small scale sizes.
ii. Ensuring proper grinding performance thereby eliminating vibrating shifter/sieving since the cassava products can be re-grinded to finer particles after pressing and frying to ensure no wastage.
iii. To save time and cost of processing cassava products by the average family.
1.7 Scope of study
The scope of the project is to design and fabricate a viable motorized cassava grater which would be useful for home-use, retailers and small scale farmers and ;
i. To obtain some data or information that will be required and that are suitable in the design and fabrication of cassava grater.
ii. To select suitable materials based on the result of the analysis for the fabrication of the machine.
iii. To prepare a neat and detailed working drawing for the fabrication process..