Design, Fabrication And Performance Evaluation Of Pedal Operated Groundnut Decorticator

Project and Seminar Material for Agricultural and Bio-Environmental Engineering

Design, Fabrication And Performance Evaluation Of Pedal Operated Groundnut Decorticator


Shelling of groundnut pods (Arachis hypegea) by hand is tedious, laborious and unhygienic with low efficiencies. As a result farmer get low income due to amount of broken kernels and a lot of time is lost in the tedious shelling operation. To overcome this problem, pertinent parameters that influence shelling efficiency of pedal operated groundnut decorticator were identified. Pedal operated decorticator were designed and fabricated with chain and sprocket of bicycle and aluminum spike tooth is used and evaluation was done in the department of Agricultural and Bio-Environmental Engineering Technology, Kwara State Polytechnic, Ilorin because it was affordable and locally fabricated. A rotary motion mechanism was employed to drive the decorticating drum while concave screen was fixed. The selection of the screen aperture was based on the size and shape of the groundnut seed. The factors considered in this project work were feed rate and operators characteristics (height, weight and knuckle lengths). The evaluation of machine was conducted while time was taken for each tests. The result of the pedal operated groundnut decorticator revealed that operator III has the maximum shelling efficiency of 65% was achieved at 9minutes, 16 seconds and breakage of 9% and throughput capacity of 15.3kg/hr. Operator II was the optimum shelling efficiency of 56% at 12 minutes 44 seconds and breakage of 8% and throughput capacity of 14kg/hr. Operator I has the minimum shelling efficiency of 47% at 11 minutes 44 seconds and breakage of 16% and throughput capacity of 15kg/hr. The total amount used for the fabrication of the pedal operated groundnut decorticator was totaled to Ninety-two Thousand and Seven Hundred Naira only (N92,700.00). The result of the fabricator implies that the characteristics of Operator III is recommended to farmers who shell for seed can now obtained more seed shelled with low breakage and will get more income.

Table of Contents

  • Cover Page
  • Title Page
  • Certification
  • Dedication
  • Acknowledgements
  • Abstract
  • Table of Contents
  • List of Tables
  • List of Figures
  • List of Plates

Chapter One:


  • 1.1 Background to the Study
  • 1.2 Statement of the Problems
  • 1.3 Objective of the Project
  • 1.4 Justification of the Project
  • 1.5 Scope of the Study

Chapter Two:

Literature Review

  • 2.1 Physical Properties of Groundnut
  • 2.1.1 Determination of Size
  • 2.1.2 Determination of Coefficient of Friction
  • 2.1.3 Determination of Moisture Content
  • 2.1.4 Angle of Repose
  • 2.1.5 Porosity
  • 2.1.6 Surface Area
  • 2.2 History of Groundnut in Nigeria
  • 2.3 Agronomy of Groundnut
  • 2.4 Post Harvest Losses of Groundnut Seeds
  • 2.5 Economic Importance of Groundnut Seed
  • 2.6 Factor Affecting Shelling Operation
  • 2.6.1 Cylinder-Concave Clearance
  • 2.6.2 Sieve Shake
  • 2.7 Description of some Threshing Equipment
  • 2.7.1 Maize Sheller
  • 2.7.2 Maize Dehusker-cum Sheller
  • 2.7.3: Hand Maize Sheller
  • 2.7.4 Groundnut Striper
  • 2.7.5: Groundnut Thresher
  • 2.7.6: Groundnut Decorticator Manually Operated
  • 2.7.7 Power Operated Groundnut Decorticator
  • 2.7.8 Pedal Operated Thresher (Paddy Thresher):
  • 2.8 Terminology Related to Thresher
  • 2.8.1 Feed Rate
  • 2.8.2 Clean Grain
  • 2.8.3 Concave Clearance
  • 2.8.4 Cleaning Efficiency
  • 2.8.5 Threshing Efficiency
  • 2.9 Review of Existing work

Chapter Three:

Material and Methods

  • 3.1 Physical Properties of Biological Materials
  • 3.1.1 Sample Preparation
  • 3.1.2 Determination of Size and Shape
  • 3.1.3 Determination of Moisture Content
  • 3.1.4 Determination of Mass, Volume and Density
  • 3.1.5 Determination of Coefficient of Static Friction
  • 3.1.6 Determination of Angle of Repose
  • 3.2 Description of the Groundnut Pedal Operated Machine
  • 3.3 Design Consideration
  • 3.4 Design Calculation and Analysis
  • 3.4.1 Design for Hopper
  • 3.4.2. Design for Decorticating Unit
  • 3.4.3 Design of Chain Drive
  • Determination of Chain Length between the Pedal and Idler Shaft
  • Determination of Chain Length Between the Idler Shaft and Decorticating Shaft
  • Determination of Chain Length Between the Idler Shaft and Blower Shaft
  • 3.5 Material Selection
  • 3.6 Fabrication Procedure and Assembly
  • 3.6.1 Fabrication of Main Frame
  • 3.6.2 Fabrication of Hopper
  • 3.6.3 Fabrication of Bicycle Pedal and Chain Drive
  • 3.6.4 Fabrication of Decorticating Drum
  • 3.6.5 Decorticating Screen
  • 3.6.6 Operator Seat
  • 3.6.7 Aluminum Spike Tooth
  • 3.7 Principle of Operation of the Machine
  • 3.8 Cost Analysis
  • 3.9 Performance Evaluation
  • 3.9.1 Sourcing of Experimental Material
  • 3.9.2 Sample Preparation
  • 3.9.3 Experimental Procedure
  • 3.9.4 Instrumentation Used for the Experiment
  • 3.9.5 Design Layout
  • 3.9.6 Output Parameter

Chapter Four:

Results and Discussion

  • 4.0 Results and Discussion
  • 4.1 Results
  • 4.2. Discussion
  • 4.2.1 Physical Properties of Groundnut Pods
  • 4.2.2 Effect of Operator Parameter Threshing Efficiency

Chapter Five:

Conclusions and Recommendations

  • 5.1 Conclusions
  • 5.2 Recommendations
  • References
  • Appendix A
  • Appendix B

List of Tables

  • Table 3.1: Sample Preparation
  • Table 4.1 Data Sheet for Physical Properties of Groundnut Pods
  • Table 4.2 Data Sheet for Output Parameters
  • Table 4.3 Data Sheet for Output
  • Table 4.4 Average Performance of Thresher

List of Figures

  • Figure 2.1: Maize Sheller
  • Figure 2.2: Hand Maize Sheller
  • Figure 2.3: Groundnut Thresher
  • Figure 2.4: Manual Operated Groundnut Decorticator (Oscillating Type)
  • Figure 2.5 Power Operated Groundnut Decorticator

List of Plates

  • Plate 2.1: Groundnut Pod
  • Plate 3.1: Sample of Groundnut Seed
  • Plate 3.2: Determination of Coefficient of Static Friction and Angle of Repose
  • Plate 3.3: Pedal Operated Groundnut Decorticator
  • Plate 3.3: Digital Venier Caliper
  • Plate 3.4: Digital Weighing Scale
  • Plate 3.5: Digital Stop Watch Scale
  • Plate 3.6: Electric Oven
  • Plate 3.7: Tachometer

Chapter One


1.1 Background to the Study

Groundnut (Arachis hypogaea) is a species in the legume or beans family (Ashishand Handa, 2014; Atiku et al., 2014). It was first cultivated in Peru. Its seed contain about 63% carbohydrate, 19% protein and 6.5% oil. Groundnuts are grown in tropical and subtropical climate regions and warmer parts of temperature regions and it is low growing annual plant and has a variety of uses. Prior to its usage however groundnut need to undergo preprocessing which include drying and shelling. Removing of kernels from the pod is generally referred to as shelling or “decorticating” (Maduako et al., 2006). In Nigeria groundnut is mainly decorticate by hands (traditional method). This method is not hygienic as dirt from hands and mouth could pose health risk from the nuts. (FAO. 2001).

Shelling is a fundamental step in groundnut processing as it allows the kernel and hull to be used as well as other post harvesting technologies to take place such as oil extraction or in hull briquetting (Pradhanaet al., 2010). Shelling is usually carried out on the farm just before the farmer sells his product for the following reasons: Kernel do not store as well as nuts in the shell and groundnuts in the shell are fifty per cent heavier than kernels alone and therefore costlier to transport. Shelling can generally be done by hand or machine. Hand shelling is the process in which the pod is pressed between the thumb and first finger so that the kernel is released. In mechanization now we use large and smaller machinery for groundnut shelling. These machines are used in industries where large production is required. There are different methods of shelling and different machines have been fabricated and used to shell wide variety of crops under different conditions (Nyeaanga et al., 2003., Atiku et al., 2004; Gitau et al., 2013; andMaduakoet al., 2006). The peasant farmer cannot afford this machine because they are too costly and complex in operation and maintenance. Also the operator had to be trained and spare part imported. These factor increase the overall cost production which does not make any economic sense to the farmer.

1.2 Statement of the Problems

Research shows that groundnut has an inherent poor storage life, if not threshed after harvesting unlike some other crops, but in threshed forms, it can be stored for a very long period of time (Onuoha2010). Therefore, to overcome the problem associated with manual threshing and quick rate of insect infestation after harvesting, the development of groundnut decorticating machine is of paramount. Traditionally the seeds are left in the pods which would then be stored in a pot and would only be shelled when they are needed for cooking (Ngugi, 2007), shelling is one by hand or beating with a short stick or pestle and mortar, followed by winnowing (KaulandEgbo,1985). The constraints such as fatigue, high time energy inputs and inefficiency in manual shelling of groundnut led to design and fabrication of pedal operated groundnut Sheller that will go a long way in solving the problem of rural farmers that are engage in groundnut production at small and medium scale level.

1.3 Objective of the Project

The main objective of the project is to design and fabricate a pedal operated groundnut decorticator that will remove and separate the groundnut seed from the hull for domestic and industrial uses.

The Specific Objectives are to:

  1. Determine the physical properties of groundnut seed in relation to the design of pedal operated ground decorticator.
  2. Design and fabricate a pedal operated groundnut decorticator
  3. Evaluate the performance of the decorticator in terms of decorticating. Efficiency, percentage of breakage, percentage of shelled seed throughput capacity.

1.4 Justification of the Project

Due to high lose that are recorded due to lack of adequate power supply, these are expected to be achieve at the end of the project.We can save the time and money by using pedal operated groundnut decorticator, limited number of labour will be required, groundnut will be available for domestic and industrial use. The fabrication of the machine will encourage the farmers to grow more groundnuts.

The machine would overcome the traditional method by reducing wastage due to crack or crushed groundnut, to increase the efficiency, to reduce the hard work and to reduced time to shell the groundnut, to develop a low cost machine which can be used by farmer to convert their semi-finished (shell groundnut) into finished product (groundnut) and it satisfies the need of village people to earn more money.

1.5 Scope of the Study

Groundnut is the sixth most important oil seed crop in the world and is widely cultivated in Nigeria. The project work is limited to groundnut seed. The variable factors to be considered in this study were feed rate and characteristics of the operator (weight, height and knuckle length).

Chapter Five

Conclusions and Recommendations

5.1 Conclusions

The following conclusion can be drawn from the performance carried out on groundnut decorticator.

  1. The lower the knuckle length of the operator the higher the threshing efficiency of the operator.
  2. The lower the weight of the operator the higher the throughput capacity of the machine.
  3. The average performance of the thresher at average operating speed of 245.4pm are threshing efficiency 56%, unthreshed efficiency 4.7%, breakage 11% and throughput capacity 14.8kg/hr

5.2 Recommendations

A pedal operated groundnut decorticator was fabricated and tested for performance.

  1. To study the optimum speed of the decorticator for best performance
  2. To work on the separator which included the blower for separating the seeds from the shaft so as to save time for cleaning process.
  3. To study the physical properties of the groundnut seed for effective performance of the machine.

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