(TITLE)

IMPROVEMENT OF A PEDAL OPERATED PORTABLE SHELLING MACHINE FOR

CORN (Zea mays L.)

FRANK ADRIAN V. VILLANUEVA

CHAPTER 1

INTRODUCTION

Nature and Importance of the Study

Corn (Zea maysL.) is a cereal crop that has been cultivated as a food crop since ancient

times. Itis native to Central and South America.It has a variety of usessuch as food

consumption,flour, oil, fuel in the form of ethanol or for livestock feed. The corn plant is an

efficient factory for converting large amounts of radiantenergy from the sun into a stable form of

chemical energy stored as cellulose, oil andstarch. It has proven to be a very versatile grain

(Davis.,2001).

Maize (corn) is one of the most important staple crops in the world. In Kenya, for

example, 45% of the population considers Ugali (maize meal) to be their survival food, making it

the most consumed food of the country. Maize also accounts for 43% of the Latin American diet.

In Asia, maize production is over 200 billion kilograms a year and it is expected that the total

maize production in developing countries will eventually overtake production in industrialized

countries(D-Lab Corn Sheller Background Copyright © Massachusetts Institute of Technology

.Accessed on July 30, 2014).

In many developing nations, simple agricultural tasks can require huge amounts of labor

due to a lack of appropriate technology. One such task is shelling maize kernels from the cob for

storage purposes. Also in some rural areas of developing countries, the maize kernels are

removed from the cob by hand in a process called “shelling”. Shelling the annual maize harvest

by hand typically takes weeks and may pull children out of school, since processing food for

survival takes priority over education in subsistence farming households. The hardened, dry

maize can also be painful to shell and lead to hand injuries(D-Lab Corn Sheller Background

Copyright © Massachusetts Institute of Technology. Accessed on July 30, 2014).

Another option is a simple tool that makes it possible to shell maize several times faster

than by hand. The device has the additional advantages of being robust, portable, transparent to

users and only a fraction of the cost of other alternatives commonly on the market. One of those

alternatives is the pedal operated “Degraining /Shelling machine” ( Marroquin et.al., 2010).

Objectives of the Study

The main objective of the study was to improve a pedal operated portable shelling

machine for corn. Specifically it aimed to:

1. Evaluate the technical performance of the pedal operated shelling machine such as the

shelling efficiency and the percent shelling recovery; and

2. Determine the economic performances of the pedal-operated corn sheller.

Scope and Limitation of the Study

This study focused only on the improvement of the pedal operated portable shelling

machine with the considerations on certain parameters such as operation and fabrication costs,

capacity of the pedal operated portable shelling machine, amount and quality of corn kernels

removed from the cob, and the efficiency of the machine.

Time and Place of the Study

This study will be conducted at the _______________, Department of Agricultural

Engineering, Visayas State University, Baybay City form _______ to ___________.

REVIEW OF LITERATURE

CORN (Zea mays L.)

Maize (corn) is one of the most important staple crops in the world. In Kenya, for

example, 45% of the population considers Ugali (maize meal) to be their survival food, making it

the most consumed food of the country. Maize also accounts for 43% of the Latin American diet.

In Asia, maize production is over 200 billion kilograms a year and it is expected that the total

maize production in developing countries will eventually overtake production in industrialized

countries ((D-Lab Corn Sheller Background Copyright © Massachusetts Institute of Technology.

Accessed on July 30, 2014).

Threshing or Shelling

de Lucia et. al., (1994), threshing or shelling is the process of separating the grains, or the

shells in the case of groundnuts, from the portion of the plant that holds them. This separation,

done by hand or machine, is obtained by threshing, by friction or by shaking the products; the

difficulty of the process depends on the varieties grown, and on the moisture content and the

degree of maturity of the grain. Threshing or shelling operations follow the harvest and whatever

pre-drying of the crop is undertaken. These operations may be carried out in the field or on the

farm, by hand or with the help of animals or machines.

According to PAES 208: 2000. Agricultural Machinery: Power-Operated Corn Sheller –

Specifications, for better understanding about the shelling process of corn, the following

important terminologies were defined:

a. corn cob- part of the ear corn where the kernels are attached.

b. corn ear- pistillate inflorescence of the plant Zea mays L., enclosed with a leaf-like

protective covering known as husk.

c. kernel-dry and indehiscent seed developed from the ovary of the ear corn.

d. kernel-ear corn ratio- ratio of the weight of the corn kernel present in the ear corn to

the weight of the ear corn

e. mechanically damaged kernels- kernels that were broken and/or scratched as a

result of shelling operation

f. net cracked kernel- difference between the percent cracked sample taken before and

after the shelling operation.

g. purity- ratio of the weight of clean corn kernels, to the total weight of unclean corn

kernels sample, expressed in percent.

h. scattering loss- ratio of the weight of corn kernels that fell out from the machine

during shelling operation to the weight of the total corn kernel input of the sheller,

expressed in percent

i. separation loss- ratio of the weight of corn kernels that come out of the shelling

chamber with the cobs at the cob outlet, to the weight of the total corn kernel input of

the sheller, expressed in percent

j. shelled kernels- whole and damaged corn kernels separated from the cob after

shelling

k. shelling efficiency- ratio of the weight of the shelled corn kernels collected at all

outlets, to the total corn kernel input of the sheller, expressed in percent

l. shelling recovery- ratio of the weight of the shelled corn kernels collected at the

main outlet, to the total weight of the corn kernel input of the sheller, expressed in

percent.

m. moisture content- amount of moisture in the kernel expressed as percentage of the

total weight of the sample, dry basis

Calculated as:

Moisture Content, % d.b. = [(Mo – M1)/ M1] x 100

Where:

Mo = initial mass in grams of the test portion

M1 = mass in grams of the dry test portion

Moisture Content.

de Lucia et. al., (1994), the amount of moisture present in a corn plays a vital rule in

shelling process. The higher the moisture content, the lesser the possibilities of removing the

kernels from the corn cob and causing more damage to the corn. On the other hand, the lower

moisture content i.e., the corn is too dry will eventually cause the corn kernels to crack that will

result to increase in losses.

Manual Shelling of Corn

The easiest traditional system for shelling maize is to press the thumbs on the grains in

order to detach them from the ears. Another simple and common shelling method is to rub two

ears of maize against other. These methods require a lot of labor, however. It is calculated that a

worker can hand-shell only a few kilograms an hour (de Lucia et. al., 1994). Also in some rural

areas of developing countries, the maize kernels are removed from the cob by hand in a process

called “shelling”. Shelling the annual maize harvest by hand typically takes weeks and may pull

children out of school, since processing food for survival takes priority over education in

subsistence farming households. The hardened, dry maize can also be painful to shell and lead to

hand injuries (D-Lab Corn Sheller Background Copyright © Massachusetts Institute of

Technology. Accessed on July 30, 2014).

Pedal Operated Degraining /Shelling machine

Another option is a simple tool that makes it possible to shell maize several times faster than

by hand. The device has the additional advantages of being robust, portable, transparent to users

and only a fraction of the cost of other alternatives commonly on the market. One of those

alternatives is the pedal operated “Degraining /Shelling machine”. Pedal power can be harnessed

for countless applications which would otherwise require electricity (which may not be

available) or hand power (which is far more effort). They can be built using locally available

materials and can be easily adapted to suit the needs of local people. They free the user from

rising energy costs, can be used anywhere, produce no pollution and provide healthy exercise.

The pedal motion is aided by a flywheelmade from a bicycle wheel weighted withconcrete.

The wheel itself is adapted to acceptdrive sprockets on both sides of thehub.The main frame is

made from steel and asection cut from an old bicycle frame incorporatesthe crankset. Derailleurs

keep the chain intension as well as providing a method to changegear.The machine is easy to

operate, easy to maintain andreasonably portable. It can be used anywhere by virtually anyone.

It’s also a simple matter to switch from degraining to milling by unbolting one appliance

andattaching the other ( Marroquin et.al.,2010).

According to PAES 209:2000- Agricultural Machinery: Power-Operated Corn Sheller-

Methods of Tests. These are the Formulas Used for Calculations and Testing of the Corn Sheller.

1. Kernel-ear corn ratio (Re)

Re = Wk / We

where:

Wk is the weight of kernel, g

We is the weight of the ear corn, g

2. Capacity

a) Actual capacity (Ca), kg/h

Ca = Wc / To

where:

Wc is the weight of shelled kernel, kg

To is the duration of operation, h

b) Corrected capacity (CC), kg/h (at 100% purity, 20% moisture content)

Cc =

x P x Co

where:

Cc is the corrected capacity, kg/h

Co is the actual capacity, kg/h

MCo is the observed moisture content, %

MCm is the kernel moisture content, at 20%

P is the kernel purity, %

3. Purity (P), %

P =

x 100

where:

Wu is the weight of uncleaned kernel, g

WC is the weight of cleaned kernel, g

4. Separation Loss (S1)

a) Amount

Sl =

b) Percentage

Sl , % =

5. Unshelled Loss (U1)

a) Amount

Ul, kg =

b) Percentage

Ul , % =

6. Scattering loss (SC l), %

Ul , % =

7. Shelling Efficiency (Se) , %

Se ,% =

or = 100% - Unshelled loss (%)

8. Shelling Recovery (Sr), %

Sr % =

9. Cracked kernel (Cg), %

Cg =

10. Mechanically damaged kernel (Dg), %

Dg =