Design And Fabrication Of A Pedal Propelled Cassava Grinding Machine

The purpose of this technical study was to do a design analysis in order to ascertain the performance and output capacity of a pedal propelled cassava grinding machine that is very efficient and affordable for rural farmers (dwellers) who cannot afford petrol and diesel engines as a prime mover for garri processing. In the design, the human expended for an average age man of 70kg (1501b) at a cycling speed range of 16km/h – 24km/h or 233 r.p.m was used and after the analysis the efficiency and human power required to drive the shaft was calculated to be 56% and 1.02hp respectively. The machine which is very cheap and affordable is highly recommended for farmers as it can deliver an output capacity of 58:59kg of cassava per hour and can produce a mechanical advantage of 0.42 which is less than 1 as recommended under simple machines.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• PROBLEM STATEMENT
• AIM OF THE STUDY
• OBJECTIVE OF THE STUDY
• SCOPE OF THE STUDY
• BENEFIT OF THE STUDY

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF CASSAVA
• REVIEW OF DIFFERENT GRATING MACHINE
• ECONOMIC IMPORTANCE OF CASSAVA PRODUCT
• STEPS OR PROCEDURE FOR CASSAVA PROCESSING
• TYPES OF CASSAVA GRATER
• FACTORS AFFECTING THE GRATING PERFORMANCE
• IMPORTANCE OF CASSAVA
• USES OF CASSAVA
• METHOD OF PEELING CASSAVA

CHAPTER THREE

METHODOLOGY

• MATERIALS AND METHOD
• DESIGN ANALYSIS

CHAPTER FOUR

• RESULT AND DISCUSSION

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION

REFERENCES

CHAPTER ONE

1.1                                             INTRODUCTION

Cassava (Manihot Esculenta) is a root tuber crop as the tuber develops from the root unlike yam (a stem tuber) which develops from the stem (Omoniyi et al., 1991). It is a source of carbohydrate; it contains some vitamins such as A and C and also contains phosphorus and iron (Omoniyi et al., 1991). Cassava is commonly grown in the Southern part of Nigeria. It is tolerant of poor soils but grows better on a well-drained sandy loam soil. Cassava is propagated by stem and the tuber is normally processed to some forms of food such as garri, akpu (fufu) and cassava flour which contain mainly carbohydrate a major source of energy. Cassava tuber contains hydrocyanic acid which is dangerous to human health (Omoruyi et al., 1991). This acid can be removed through proper processing of the cassava tuber.

In Nigeria, cassava is very essential as it serves as a number one stable food, used to produce starch, garri flour and it peels are also used to feed livestock .The process of transforming cassava tubers into pulp form is known as grating. Peeled cassava tubers are feel into the hopper made of mild steel then to the cylindrical drum which the grind the cassava into a mashed form.The rate of grinding will depend on the cycling speed of the person riding the pedal. The pedal (attached to the crank) is that part that gives effort (energy) for motion to take place.The means of motion transmission is through a chain and then through a belt mounted on a pulley which is mounted on the transmission shaft supported by bearings and a flywheel at one end to restore energy lost from the system.

1.1                                    BACKGROUND STUDY

Cassava was introduced to Africa by the Portuguese more than 300 years ago close to the mouth of the Congo River by Portuguese explorers and traders from Brazil, and today is the main sources of carbohydrates in sub-Sahara Africa. The plant grows as a bush or small tree. From there it was diffused by Africans, to many parts of sub-Saharan Africa over a period of two to three hundred years. In the course of its spreading across the continent, cassava has replaced traditional staples such as maize and yam, and has been successfully nominated into farming systems. It was initially adopted as a famine reserve crop as it provided a more reliable source of food during drought, locust attacks and the hungry season, the period before seasonal food crops are ready for harvesting. ( Bencini, 1991 )

Cassava is a staple crop in many tropical countries and is harvested for its tubers, which are grated into pasty form and pounded into a spread or flour. It is a member of the Euphorbiaceous, which includes those red flowered poinsettias we get at Christmas and those little spurge weeds found in USA gardens. Its tubers are toxic and must be processed to eat, but they provide a lot of calories in the form of carbohydrates. That’s not of much interest to those in the North, who avoid calories, but it is the weapon against famine in the South. At present, approximately half of the world production of cassava is in Africa where it is cultivated in around 40 countries, stretching through a wide belt from Madagascar in the southeast to Senegal and Cape Verde in the northwest. Approximately 75 percent of Africa’s cassava output is harvested in Nigeria, the Democratic Republic of Congo, Ghana, Tanzania Mozambique,Niger and Cameroon. Cassava is grown by millions of pauper African farmers, many of them are women, often on marginal land.

For these people, the crop is vital for both food security and income generation. Cassava is vegetative propagated through stem cuttings and produces well on poor soils. The tubers may be kept in the soil for not less than 9 months before it can be harvest. This secures rural farmers a carbohydrate source in years with adverse growth conditions where other crops fail and famine Would otherwise prevail. These features and high crop yield contribute to the role of cassava in Africa, South East Asia, and South America (Nweke et aI., 2002).

Also cassava can be grown on poor soil with no investment in irrigation, fertilizers or pesticides. Currently, the African crop is threatened by African cassava mosaic virus, which can reduce Yields by 75percent. Over the past decade, the virus has caused famine in several local regions of central Africa. The disease is prevalent because the African cassava varieties, having been introduced, have no natural defense against the virus. Cassava contains varying amounts of cyanide, a toxin that protects the plant from insects. Indigenous people have learned to avoid poisoning themselves by spitting into batches of the ground tubers; the saliva introduces bacteria and fungi, which activate an enzyme that breaks down the cyanide. ( Hahn, 2006 )

Villagers accomplish the same thing by depositing freshly dug cassava tubers into a community pond; microorganisms in the water degrade the cyanide. It is speculated that starvation indirectly led to these culinary rituals; starving people may have found that, having once spit out the bitter cassava tubers, then trying them again, the bitter taste was lessened. The diversity of the plant is remarkable. “There must be thousands of different varieties. In Brazil, every little village has its own varieties. There are bitter ones, sweet ones, even ones used as baby food.”(Schaal et al.1999) Burgeoning interest in the crop in recent times results from the realization of the potential of cassava as a food security and emergence crop which could generate employment for the rural people and foreign exchange for the country. Since 1990, the Government, through the Ministry of Food and Agriculture, has demonstrated its determination and commitment to promote cassava for the alleviation of poverty particularly in rural households and communities. ( Hahn, 1986)

The main reasons for expansion of cassava are population growth, famines or seasonal hunger and market availability. In Nigeria, cassava is moving from a starvation-prevention crop to a cash crop for local urban consumption. The next stage is to develop novel uses for the crop, such as livestock feed and industrial uses,storage and to identify new markets. The top cassava producers are, in order, Nigeria, Brazil, Thailand and Indonesia (the next six countries are all in Africa).

The major part of processing cassava tuber into garri after peeling and washing the tuber is “grating”. Grating is milling or grinding of cassava tuber into smaller units (granules) by scratching and rubbing the tuber against a rough metal sheet in order to increase the surface area of the tuber and ease removal of water that contains hydrocyanic acid during dewatering/fermentation process. The grating process is manual and usually done by women in the rural areas using a primitive method by scratching and rubbing cassava tubers against a sharp and rough metallic plate. This grating method is cumbersome, time consuming and can result in injury to the hands. Cassava tuber must be processed 2-3 days after harvesting otherwise it would get spoil (Adetunji and Quadri, 2011). Fermentation of the grated cassava is done after grating the cassava tuber by putting it in a muslin bag and compressed for 2-3 days. This is done to remove or reduce the hydrocyanic acid content in the cassava tuber and also to give the normal taste of garri. The fermented cassava is sieved through a screen of 1 to 2 mm in diameter, fried by stirring inside a hot frying pan in order to expel water and produce garri. Therefore, grating of cassava tubers is necessary in order to produce garri and it is one of the methods of increasing the shelf-life cassava. The objective of this study was to design and fabricate a simple pedal operated cassava grater for the rural dwellers. Understanding the theory for the design of shaft is very important to prevent failure of the shaft during the operation of a machine. This is achieved by designing and calculating the appropriate diameter of the shaft that could withstand stresses due to torsional and bending moments.

1.2                                   PROBLEM STATEMENT

The cost of producing and running a motorized or electric cassava grater is high (for rural farmers) in that it uses electric motor or fuel generator and it produces much noise and emits carbon-monoxide which is dangerous to human health. In other to solve this problem a pedal propelled cassava grinding machine was built which is economical in that it uses no fuel or electricity and also produces less noise.

1.3                                      AIM OF THE STUDY

This study is aimed at ascertaining the performance analysis and output capacity of a humanly powered cassava grinds, m/c which will encourage rural farmers to invest into it and also provide a ground for researchers to improve on.

1.4.                                OBJECTIVES OF THE STUDY

The objectives of this project are as follow:

1. To design a cassava grater (dimensions) to the home use-small scale sizes.
2. 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.

• To provide food to the average family.

1.5                                                  SCOPE OF STUDY

The scope of the project is to design and fabricate a pedal propelled cassava grater which would be useful for home-use, retailers and small scale farmers and;

1. To obtain some data or information that will be required and that are suitable in the design and fabrication of cassava grater.
2. To select suitable materials based on the result of the analysis for the fabrication of the machine.

• To prepare a neat and detailed working drawing for the fabrication process.

1.6                                       BENEFIT OF STUDY

This work will be useful in rural areas where farmers cannot afford to purchase petrol and diesel powered cassava grinding machine.