(Mechanical Engineering)



            A machine for corn shelling is highly and greatly needed to consistency of usage of corn in local and international levels.

            With regards to this indispensable needs, a corn shelling machine is designed which operates to remove the corn grains and leaving the cobs intact.

            In attainment to this design objective and aims, a proper considerations was given to the machinability factor which includes; installation, simplification, durability, choice material, machine, low costing and prolonged life span when operate with high utilization with minimal down fine.

            The design details are given which includes such items as materials and their characteristic adaptation methodology, the parts relations with the whole device and the effect of the finished product upon which an inquisitive mine can make collection of fact in future which related to this project.



Literature Review

Materials Selection

The Shelling Unit

The Construction and Design Method


SYMBOLS                                                    UNITS

N – Factor of safety                            Kilogram

M – Mass                                                        Kilogram

Dia – Diameter                                                Meters

M – Bending moment                         Meters

T – Torque                                                       Newton Meter

V – Velocity                                       Newton-second

T – Time                                                          Seconds

I – Moment of Initial                          Kilogram (meter)

g – Acceleration due to gravity                      Newton (meter)

G – Modulus of Rigidity                                Newton (meter)

P – Pressure                                                     Newton (meter)

P – Power                                                        Kilowatts

F – Force                                                         Newton’s

H – Height                                                      Meter

Rpm – Revolution per minute                        

R – Radius                                                      Meter

V – Volume                                                    Meter

Wt – Weight                                       Newton’s

D – Density                                                     Kilogram-meter3

Pc – Critical load                                             Newton

L – Length                                                      Meter

W – Width                                                      Meter

d - Bending stress                                           Newton

y – Torsional stress                              Newton/meter




1.1              Purpose of construction                                 

1.2              Importance and Specification of the project             

12.1          Barrels

12.2          Hopper                       

12.3          Receptacle                                                      

12.4          Spikes                                     

12.5          Cobs Outlets                          

12.6          Conveyors                                          

12.7          Discharge chamber

12.8          Collector/Outlet                                 

12.9          Inlet                                                    

12.10      Spinning Vane                                               


LITERATURE REVIEW                 

2.1              Hand shelling method                        

2.2              Direct linkages and its limitation                   

2.3              Refined Design and its specification                         

2.3.1        Functionability                                               

2.3.2        Reliability                                           

2.3.3        Durability                                                       

2.3.4        Simplicity                                                                               

2.3.5        Portability and space                                      

2.3.6        Operational Procedures                                                          

2.3.7        Power supplies                                                           

2.3.8        Material and labour needs                  

2.3.9        Maintenance                                                   


MATERIAL SELECTION                                                   

3.1       Material selection and Design of Shaft                                 

3.2       Selection and Location of Bearings                           

3.2.1    Bearing Lubrication                                       

3.2.2    Bearing Housing                                                        

3.3       Electric Motor Selection                    

3.4       Selection of Pulley Material               


THE SHELLING UNIT                                                       

4.1              The frame                                           

4.2              The spinning shaft                                          

4.2.1        Determination of axial stress due to axial load of the shaft

4.2.2        Determination of Torsional Moment             

4.2.3        Determination of Torsional stress                  

4.2.4        Determination of Maximum Bending stress due to bending load

4.2.5        Determination of Maximum Bending Moment         

4.2.6        Determination of safety factor                                  

4.3              Belt Drive                                                      

4.3.1        Advantage of the Belt Drive                                     

4.3.2        Belt Calculations: Determination of Driving Power              



5.1              Metal Hopper                                                             

5.2              T he shelling unit                                                                    

5.3              Outlet                                                                                     

5.4              Barrel                                                                         

5.5              Perforated metal                                

5.6              Significance of Assembly                              

5.7              Operation of the corn shelling Machine and its efficiency    

5.8              Conclusion                                                     

5.9              Recommendation                                           

5.9.1        Cost Analysis Table                                       





            We have participated indeed in mass shelling of corn using the most primitive, cumbersome, and difficult method of hand shelling which encourages rime consuming and human stressfulness.  Corn otherwise known as “Oka” in Igbo tribe is mostly sued seed across all the tribe in this country today.  It is widely used in homes, hotels, and schools for eating and seedling process (when dried).  It is therefore very rare to see any Nigerian who has not tested it in one way or the other.

            Now, since it is very imperative for dieting inclusively, it can be refined to form varieties of food supplementary diet such as making of Akamu (pap), Semovita corn pounded, corn mill etc. Today, in our industrial sectors such as ceramics and biscuit industry, it is widely used for making of biscuit, flouring for bakery of the bread, and corn mill.  Infact to summarize all this, junked food that are baked in supermarket today are mostly involves corn in making them.

            In the light of this as technology advance forward, an introduction of this machine (sheller) made manifest and come into existence which is more stressless, easy to operate, low costing, and time reduction with high degree of production volume and efficiency.  Modifications have also made it possible to be manually and electro-mechanical operated type depending on the choice of design and the speed of shaft required.

            Today, with the aid of this, it has created availability of corn sheller (shelling machine) even in the market which indeed removes our difficulties and impossibilities when using and engaging with modern method of design.


            This project is meant to achieve the following purposes.

(1)               To design and construct a corn sheller which is easy to operate with high degree of efficiency.

(2)               To design and construct a machine (corn sheller) that would save time and cost, with high degree of production volume.

(3)               To design and construct a corn sheller that would not have much breaking effect of grains, leaving the cobs intact during the process.

(4)               To design and construct a corn sheller that is economic and have little or no complication in maintenance

(5)               To design and construct a corn sheller with high percentage of local technology.

(6)               To design and construct a machine that is cost effective manual stress reduction.


The importance attached to this design is the facilitation and the production of voluminous corn shelling without much time and without encountering much breakage of the grains of the corn in shortest possible time.

The specification was obtained considering the items or component used and the hopper and barrel dimensions put into consideration as well.  The design parameter for corn sheller machine are:

1.2.1        BARREL

(a)        Outer barrel:-            This barrel do not rotates with the shaft rather stands on itself inside the shelling chambers.  It is a half of glindrical shaped perforated below to enable shelled corn to rush out to the conveyor to the outlet basin.  It is weld and tight at ges at the end for the location of the bearings for the shaft.  At the lower end of one is an open segments serving as outlet for the cobs and a hood is built covering it.

            Below is a complete drawing of the outer barrel shown.


(B)       Inner barrel:- This cylindrical barrel rotates with the shaft support by  end to end bearings.  The diameter of the shaft is and for the inner barrel’s diameter is, having number of spikes measuring from the barrel surface and also wounded vanes that does the shelling process.

            Diameter of inner barrel is and its length is and consequently the diameter of the shaft and having a length of.

            Below is the diagram of the inner barrel










1.2.2        HOPPER

This is similar to a port but the difference is that it is bigger and not covered like the port.  It is eight rapezoid or rectangular in shape, each shape chose have its advantage and disadvantages.  It has an entry through which the corn enters the shelling chamber and the inner engulfing the shaft.  It is obtained after cutting a mild steel and welding it with gauge 12 electrode and it’s dimension is.

The diagram is shown below.











1.2.3        RECEPTACLE

This is the outer funnel that collects the shelled corn from the conveyor to the outside.

1.2.4        SPIKES

This is the rod attached to the surface of inner barrel which does the shelling process with the inner barrel and the spring vanes.  It is to 27 in number and measured vertically up from the barrels surface each.

1.2.5        COB OUTLET

This is an exit through which the cobs goes out of the barrel after shelling process.

1.2.6        CONVEYOR

This is the carriers that conveys/carry's the cobs out of the barrel after shelling process.


These are the holes perforated below the outer barrel through which the shelled grain corn falls out to the conveyor.


This is curved mild steel welded below the perforated outer barrel inclined to enable the falling out of the shelled corn to the receptacle.

1.2.9        INLET

This is the particular place in the hopper through which the corn enters the shelling unit/chamber for shelling process it is measured as. SPINNING VANES

            This is made up of flat tiny metal welded round the inner barrel together it the spikes.  It is the part of the machine where the corn is being shelled.  It is also placed horizontally wounded around the inner barrel and should be capable of withstanding impact from corn and posses good chemical resistance, high working temperature (100%) and tensile strength.  Dimensionally, it is measured 30mm from the surface of the inner barrel wounded horizontally.


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