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FINAL YEAR PROJECT REPORT
UNIVERSITY OF NAIROBI
DEPARTMENT OF MECHANICAL AND MANUFACTURING
ENGINEERING
PROJECT NO. DMM.02/2016
PROJECT REPORT TITLE: DESIGN OF A BAR SOAP MAKING
MACHINE FOR LOCAL SOAP INDUSTRY
This project report is submitted in partial fulfillment of the requirement for the
award of the degree of Bachelor of Science in Mechanical and Manufacturing
Engineering.
Submitted by: JULIUS CASEY KILILIKU F18/40222/2011
KILONZO STEPHEN WAMBUA F18/41129/2011
KIBICHII FREDRICK BITOK F18/40325/2011
Project supervisor: DAVID MUNYASI
MAY 2016
ii
DECLARATION
The content of this document is the original work based on our own research and to the best of our knowledge it has not been presented elsewhere for academic purposes. JULIUS CASEY KILILIKU F18/40222/2011
Signed…………………………………. Date: …………………………… KILONZO STEPHEN WAMBUA F18/41129/2011
Signed…………………………………..Date:……………………………… KIBICHII FREDRICK BITOK F18/40325/2011 Signed…………………………………… Date: …………………………. This project is submitted as part of the Examiners Board requirement for the award of the degree of Bachelor of Science in Mechanical and Manufacturing Engineering from the University of Nairobi. Project supervisor: Eng. David Munyasi Signed …………………………………. Date: ……………………………….
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DEDICATION
We dedicate this project to our parents whose love and understanding always empowers us.
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ACKNOWLEGEMENT
We would like first to give our sincere gratitude to the Almighty God for guiding us through this
project.
We also thank our families and friends who gave us physical, financial and emotional assistance
in our project.
We appreciate the University of Nairobi through the Department of Mechanical and
Manufacturing Engineering for the material resources availed unto us throughout our project.
Our special thanks go to our project supervisor Eng. David Munyasi for allowing us to undertake
this project and for the professional and technical advice willingly accorded to us.
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Table of Contents
DECLARATION .......................................................................................................................................... ii
DEDICATION ............................................................................................................................................. iii
ACKNOWLEGEMENT .............................................................................................................................. iv
LIST OF FIGURES ................................................................................................................................... viii
LIST OF CHARTS ...................................................................................................................................... ix
LIST OF ABBREVIATIONS AND SYMBOLS ......................................................................................... x
ABSTRACT ................................................................................................................................................ xii
CHAPTER 1 ................................................................................................................................................. 1
INTRODUCTION ........................................................................................................................................ 1
1.1. SOAP ................................................................................................................................................. 1
1.2 SOAP MAKING ................................................................................................................................. 1
1.3. BAR SOAP MAKING MACHINE ................................................................................................... 1
1.4. PROBLEM STATEMENT ................................................................................................................ 2
1.5. STUDY OBJECTIVES ...................................................................................................................... 2
CHAPTER 2 ................................................................................................................................................. 3
LITERATURE REVIEW ............................................................................................................................. 3
2.1. DEFINATION ................................................................................................................................... 3
2.2. BACKGROUND ............................................................................................................................... 3
2.3. APPLICATIONS OF BAR SOAP ..................................................................................................... 3
2.4. CLASSIFICATIONS OF BAR SOAP .............................................................................................. 4
2.5. DESIGN ............................................................................................................................................. 5
2.6. RAW MATERIALS .......................................................................................................................... 5
2.7. THE FUTURE ................................................................................................................................... 5
CHAPTER 3 ................................................................................................................................................. 6
METHODOLOGY ....................................................................................................................................... 6
3.1. INTRODUCTION ............................................................................................................................. 6
3.2. A SURVEY OF BAR SOAP MAKING MACHINES CURRENTLY BEING USED IN KENYA 6
3.3. CURRENT BAR SOAP MAKING MACHINE DESIGNS .............................................................. 7
3.5. BAR SOAP MAKING MACHINE FROM ITALY .......................................................................... 8
3.5.1. Small Soap Finishing Line .......................................................................................................... 8
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3.5.2. Small soap extruder ..................................................................................................................... 9
CHAPTER 4 ............................................................................................................................................... 12
DESIGN OF BAR SOAP MAKING MACHINE ...................................................................................... 12
4.1. SELECTION OF MATERIALS ...................................................................................................... 12
4.1.1. Pulley material .......................................................................................................................... 13
4.1.2. Toothed belt material ................................................................................................................ 13
4.1.3. Extrusion shaft .......................................................................................................................... 13
4.1.4. Materials of Hopper, Stand, Mixing tank and Extrusion shaft housing .................................... 14
4.1.5. Fastener Materials ..................................................................................................................... 15
4.2. SELECTION OF MANUFACTURING METHODS FOR PARTS ............................................... 15
4.3.1. THE POWER SYSTEM ........................................................................................................... 16
4.3.2 THE FEEDING SYSTEM ......................................................................................................... 25
4.3.3 THE EXTRUSION SYSTEM ................................................................................................... 27
4.3.4. COOLING AND HEATING SYSTEM.................................................................................... 34
4.3.5. BAR SOAP EXIT SYSTEM .................................................................................................... 35
4.4. WORKING PRINCIPLE OF THE BAR SOAP MAKING MACHINE ......................................... 38
DETERMINATION OF TECHNICAL AND ECONOMIC VIABILITY ................................................. 39
5.1.1. Performance .............................................................................................................................. 39
5.1.2. Environment .............................................................................................................................. 39
5.1.3. Maintenance .............................................................................................................................. 39
5.1.4. Aesthetics .................................................................................................................................. 40
5.1.5. Safety ........................................................................................................................................ 40
5.2. ECONOMIC VIABILITY OF THE BAR SOAP MAKING MACHINE ....................................... 40
6.1. CONCLUSION ................................................................................................................................ 41
6.2. RECOMMENDATIONS ................................................................................................................. 42
REFERENCES ........................................................................................................................................... 43
APPENDIX 1: COST EVALUATION OF THE BAR SOAP MAKING MACHINE ............................. 44
APPENDIX 2: DRAWINGS ...................................................................................................................... 46
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LIST OF TABLES
Table 4.1: Mechanical properties of different grades of carbon steel ………………………..….14
Table 4.2: Mechanical properties of steel …………………………………………………….....14
Table 4.3: Measurements of the screw thread …………………………………………….…….32
Table 4.4: Inclination factor .………………..…………………………………………….…….34
Table 4.5: Properties of die materials …………………………………………………………...36
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LIST OF FIGURES Figure 3.1: Bar soap making machine from Germany ……………………………………………7
Figure 3.2: Bar soap making machine front view …………………………………………….......9
Figure 3.3: Small soap extruder …................................................................................................10
Figure 3.4: Small soap mixer …………………………………………………………………....10
Figure 4.1: Bolt and nut …………………………………………………………………….…...15
Figure 4.2: 3-phase AC motor ….……………………………………………………………….17
Figure 4.3: Timing belt………… ………………………………………………………….........18
Figure 4.4: Timing pulley system..........................................................................................…....18
Figure 4.5: Pulley and belt free body diagram....................……………………………………...19
Figure 4.6: Variable frequency working principle ………………………………………...…….21
Figure 4.7: Connection of variable speed drive to motor ….........................................................22
Figure 4.8: Small variable speed drive…………………………………………………..............23
Figure 4.9: Paddle mixer ……………………………………………...........................................24
Figure 4.10: Bearing …………………………………………………………………………….25
Figure 4.11: Hopper …………………………………………………………………………..…26
Figure 4.12: Free body diagram of a hopper .................................................................................26
Figure 4.13: Screw thread free body diagram ……….………………………………………......29
Figure 4.14: Screw thread………………………………………………………………………..32
Figure 4.15: Square tube …………………………………………………………………….......38
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LIST OF CHARTS Chart 4.1: S-N curve …………………………………………………………………………….37
x
LIST OF ABBREVIATIONS AND SYMBOLS
Kshs – Kenyan shillings
m – Meter
C – Degrees centigrade
% - Percent
$ - Dollar
ft. – Foot
kg – Kilogram
g – Grammes
in – Inch
Hg – Mercury
F – Fahrenheit
psi – pound per square inch
kpi – kip per square inch
hr – Hour
cm - Centimeter
mm – Millimeter
rpm – Revolutions per minute
lbs – Pounds
kW – Kilo-watts
Hp – Horsepower
V – Volts
Hz – Hertz
cm3 – Cubic centimeter
GPa – Giga Pascal
MPa – Mega Pascal
C – Carbon
VFD – Variable frequency drive
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AC – Alternating current
DC – Direct current
- Degree
Π – Pie
Be – Beryllium
Cr – Chromium
W – Tungsten
N – Newton
Eng. – Engineer
Fig. - Figure
Ө – Theta
USA – United States of America
US – United States
AD – anno Domini
BC – Before Christ
TM – Trade mark
Co – Cooperation
Inc. – Incorporation
L – Length
W – Width
H – Height
A – Area
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ABSTRACT
The objective of the research was to design a bar soap making machine that is cost effective, to
prepare a computer simulation model of the designed bar soap making machine and to determine
the technical and economic viability of the machine.
A survey of bar soap making machines currently used in the local industry was carried out to
establish how much they cost and their source. This was to give an overview on the need to have
a cheaper design which is simple and cost effective. This involved collection of resources from
different sources, visits to various industries to obtain important data for the project and having a
guideline on the steps involved in the design. Among the sources of information looked at is the
internet, reference books from the library and consultant engineers in the industry.
From the survey, it was found out that the soap making machines currently in use in the country
are very few and were imported mainly from USA, China or India and they came at a cost of
between Kshs.300, 000 and Kshs.500, 000. For this reason, they are only purchased by well
established companies.
A design of bar soap making machine was then made using the AutoCAD design software. A
technical and economic evaluation of the design was carried out in terms of performance,
environmental factors, maintenance, aesthetics/ergonomics, size and weight, safety and cost.
The designed bar soap making machine costs about Kshs.80, 000 to produce.
From this project, it was shown that it is economical to manufacture the new design of bar soap
making machine locally since the Kshs.80, 000 is much lower than the imported machines that
cost more than Kshs.300, 000
1
CHAPTER 1
INTRODUCTION
1.1. SOAP
Soap is a water soluble compound made by the reaction between sodium hydroxide with animal
and/or vegetable fats (oils) by a process called saponification. Soap has surface active properties
to wet a greasy surface and suspend the grease in the water for rinsing off. Other types of soaps
called detergents are made from petroleum-based products .Consumers mainly use soap for
washing, bathing and cleaning.
1.2. SOAP MAKING
There are various ways of bar soap making. These include kettle process, continuous process and
cold making process. The most popular bar soap making process is the continuous process. The
continuous process involves:
a) Splitting
The first step of the continuous process splits natural fat into fatty acids and glycerin. The
equipment used is a vertical stainless steel column (24m tall) with the diameter of the barrel
called a hydrolyzer. Molten fat is pumped into one end of the column while at the other end
water at high temperature (130°C) is introduced. This splits the fat into its two components
which are pumped out continuously as more fat and water enter. The fatty acids are then distilled
for purification.
b) Mixing
The purified fatty acids are next mixed with a precise amount of alkali, abrasives and perfume to
form soap.
c) Cooling and finishing
The soap is poured into molds and allowed to harden into a large slab. It may also be cooled in a
special freezer. The slab is cut into smaller pieces of bar size, which are then stamped and
wrapped.
1.3. BAR SOAP MAKING MACHINE
The soap making machine is made up of two main parts namely
a) The mixer
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b) The soap plodder that is made up of various components namely the extrusion shaft,
motor, pulley system, electrical heater with a thermostat, variant connected to the motor,
cooling system and stands. The machine is made of mild steel because mild steel is
cheaper and has good properties such as toughness, has good tensile strength. However
the machine has to be painted to prevent rusting since mild steel has weak resistance to
corrosion.
1.4. PROBLEM STATEMENT
Bar soap used for laundry is by far one of the most used consumer commodity in Kenya. The
market for bar soap in the country is under-utilized because by now less than ten manufacturers
are enjoying this vast market. Some of the most popular bar soap brands in Kenya are Menengai,
Whitestar, Sunlight and Jamaa. BIDCO and Pwani life are some of the major manufacturers of
soap who enjoy the monopoly. (https://cosmeticskenya.wordpress.com/2014/09/16/bar-soap-
business-in-kenya-2/)
Posted on September 16, 2014 at 6:31 pm by cosmetic Kenya limited
Imported bar soap making machines come at a high price ranging from Kshs300, 000 – 500,000.
This has led to the following problems:
(i) Locking out potential players in the bar soap making industry.
(ii) High cost of imported soaps.
With the design and development of a bar soap making machine which can be manufactured
locally, the above problems will be eliminated. This will be a major plus in the achievement of
industrialization as stipulated in the vision 2030.
1.5. STUDY OBJECTIVES
The objectives of the project are:
i) To carry out a survey of bar soap making machines currently used in the local soap
making industry.
ii) To design a bar soap making machine that is cost effective.
iii) To prepare a computer simulation model of the designed soap making machine.
iv) To determine the technical and economic viability of the bar soap making machine
3
CHAPTER 2
LITERATURE REVIEW
2.1. DEFINATION
Soap is a water soluble compound mainly used for washing, textile spinning and is an important
component for lubricants. Soaps for cleansing are obtained by treating vegetable or animal oils
and fats with a strongly alkaline solution. Soaps are key components of most lubricating greases,
which are usually emulsions of calcium soap or lithium soap and mineral oil. Soap can exist in
three forms namely bar, powder and liquid form.
2.2. BACKGROUND
The exact origins of soap are unknown though Roman sources claim it dates back to at least 600
B.C. when Phoenicians prepared it from goat's tallow and wood ash. Soap was also made by the
Celts, ancient inhabitants of Britain. Soap was used widely throughout the Roman Empire,
primarily as a medicine. Mention of soap as a cleanser does not appear until the second century
A.D. By the eighth century, soap was common in France, Italy, and Spain but it was rarely used
in the rest of Europe until as late as the 17th century.
Early soap manufacturers simply boiled a solution of wood ash and animal fat. A foam substance
formed at the top of the pot. When cooled, it hardened into soap. Around 1790, French soap
maker Nicolas Leblanc developed a method of extracting sodium hydroxide from sodium
chloride, replacing the wood ash element of soap. French chemist Eugene-Michel Chevreul put
saponification into concrete chemical terms in 1823. In saponification, the animal fat, which is
chemically neutral, splits into fatty acids, which react with alkali carbonates to form soap. Soap
was made with industrial processes by the end of the 19th century.
(http://www.madehow.com/Volume-2/Soap.html)
2.3. APPLICATIONS OF BAR SOAP
Soap can not only be used for cleaning but also for other uses as stated below;
1. Drive nails easier with less risk of splitting the wood by first rubbing it on the nail shank. .
2. Remove wallpaper glue by mixing with warm water and sponging it on the walls.
3. Lubricate the metal rails of sticking desk drawers.
4
4. Clean dirty windowsills by running the wet edge of a bar along them.
2.4. CLASSIFICATIONS OF BAR SOAP
Bar soap can be classified according to the difference in manufacturing and ingredients and also
the type of skin they are applied on.
a) Difference in Manufacturing and Ingredients
i) Common bar soaps - The commonly found basic bar soaps have in them the most
aggressive surfactants. As such, they clean dirt and from skin very well but they
themselves do not go away completely when washed. They also have a high pH
levels which make them irritating to the skin.
ii) Superfatted soap bars - When manufacturing bar soaps the process of
saponification is left incomplete, it results into bar soaps that have extra fats than
the ordinary bar soaps. Superfatting improves the moisturization of the soap and
makes it less irritating.
iii) Transparent soap bars - When glycerin is added to the ordinary bar soap, it
becomes transparent soap. However, it is still irritating to skin when compared to
the super fatted bar soaps.
(http://www.detergentsandsoaps.com/articles/bar-soap.html) (August 27 2010)
b) Bar Soap Types for Different Skin
i) Soap types for sensitive skin - People who are prone to skin allergies must
use organic soaps that come in form of bar soaps too. These soaps have
natural ingredients that are friendly to skin. Some of the bar soaps also have
herbs suitable to their sensitive skin.
ii) Soap types for dry skin - Mildest soaps are best for people with dry skin.
Look for such ingredients such as aloe Vera, vitamin E, cocoa butter or olive
oil in bar soaps for dry skin.
5
2.5. DESIGN
The design of the bar soap is determined by the shape of the die. In most cases the die is
rectangular.
2.6. RAW MATERIALS
Soap requires two major raw materials: fat and alkali. The alkali most commonly used today is
sodium hydroxide. Animal fat in the past was obtained directly from a slaughterhouse. Modern
soap makers use fat that has been processed into fatty acids. Additives are used to enhance the
color, texture and scent of soap. Perfumes are added to the soap mixture to cover the odor of dirt
and to leave behind a fresh-smelling scent. Abrasives to enhance the texture of soap include talc,
silica and marble.
2.7. THE FUTURE
The demand bar soap is dependent on the fluctuations in population, which varies with the
economy. Demand for this soap is also subject to competition from foreign manufacturers,
further reducing profits. In Kenya, bar soap production has not been embraced as the soap
making machine is unaffordable. With the growth of the population, demand for cleanliness is
increasing and this consequently leads to an increase in demand for soaps. locally manufactured
soap plodders are therefore required in large numbers.
Desirable features these soap plodders include:
i) Smooth operation
ii) Less wear and tear
iii) Low maintenance cost
6
CHAPTER 3
METHODOLOGY
3.1. INTRODUCTION
The mission of this project was to design a cheap and affordable bar soap making machine for
local use. With the completion of this project we hope that our bar soap making machine design
will be used widely throughout this great nation. We also hope that by domestically
manufacturing the bar soap making machine, the price of the machine will be drastically reduced
and this will allow creation of job opportunities within the sector in addition to contributing
towards the realization of the vision 2030.
Initially, we made a factory visit to some bar soap making industries in Kenya such as BIDCO in
Thika and Kapa Oil industries in Athi River where we found that the existing machines had been
imported mainly from India. We also visited KIRDI (Kenya Industrial Research and
Development Institute) located in South C who have a similar design. We also gathered literature
from a number of resources regarding existing machine designs from other countries that
manufacture them such as China, USA and India.
With this knowledge, we established what made a reliable soap plodder and which features and
mechanisms we would modify in order to come up with an affordable machine. We thereafter
prepared drawings using AUTO CAD and solid works.
The objective of this project was achieved through the subsequent completion of the goals
including analysis of existing soap plodder designs and determining which one can easily be
fabricated using the locally available materials.
3.2. A SURVEY OF BAR SOAP MAKING MACHINES CURRENTLY BEING USED IN
KENYA
Today’s technology offers many different bar soap making machine designs available for
purchase by the manufacturing industry. These machines are produced overseas by a wide
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variety of companies in countries like India, China and USA. The different available machines
are designed for production of different bar soap designs.
3.3. CURRENT BAR SOAP MAKING MACHINE DESIGNS
The first step to evaluating bar soap making machine design was to find out what products were
currently available in the industry. We started our research by visiting BIDCO industries to view
the machines they had. We met the engineer in charge who gave us a history of how the
company makes bar soaps using machines imported from India and China. He demonstrated the
bar soap making process to us. He said they were some of the most expensive machines
approximating at about US $ 8,000 and together with the shipping costs and taxes it would come
to over US $ 10,000.
He said that it was due to this that only a few companies could afford the machine but still with
the very high cost it would only follow that the bar soaps are manufactured and sold at a high
cost. This, he said, was the reason for the unfair competition from other bar soap importers as
they make their products cheaper which led to them not being able to work on a full capacity as
the demand was lower for locally manufactured bar soaps. We then did an online research for bar
soap making machines that are currently being imported mainly from India, China, Germany,
Italy and USA. Some of the designs are:
3.4. BAR SOAP MAKING MACHINE FROM GERMANY
Fig. 3.1: Bar soap making machine from Germany
This machine type in figure 3.1 SSP-130™ is manufactured using Superior German Technology
by Express Marine Engineering Corporation. It features:
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Physical Features
1. Size: Length 122cm, Width 61cm, Height 91cm
2. Weight: Approximately 150kg.
Technical Features
1. Inter-cooled Log Processor
2. Power Source: Single and Three Phase option
3. High pressure soap extruder of 105mHg at 00C
4. Production capacity of 50kg per hour.
5. Customized name and logo automatic roller stamping unit.
It is different from the locally fabricated one because:
1. It produces super refined high quality bar soaps
2. It produces soaps with Uniform Standard Weight
3. It has a very low maintenance cost
The machine has high extrusion pressure of 14MPa at 00C ensuring that the soap is super refined.
The circulating coolant in the cooler system allows powerful temperature control enhancements
in the plodder barrel for better soap processing. The machine is sold and serviced throughout
East and West Africa by Cosmetics & Detergents Kenya Ltd. It costs between Kshs 190,000 to
300,000.
3.5. BAR SOAP MAKING MACHINE FROM ITALY
3.5.1. Small Soap Finishing Line
They have a complete small soap finishing line as well as single small soap machines for small
companies and artisans which are affordable. These lines and machines are studied to work with
soap noodles. The standard small soap finishing line in figure 3.2 is composed by an automatic
9
mixer able to mix up to 15 kg of soap noodles with perfume and colors per batch, a simplex
plodder to refine and extrude the soap and a manual soap press.
Manual soap mixer can be used for a small capacity while the automatic mixer, about 30kg in
weight is used when there is the necessity to amalgamate additional components that are required
for more mixing time. The soap noodles, perfume and colors are mixed inside the soap mixer for
a variable time of 8-15 minutes, depending on the coloring intensity. After the mixing, the soap
base is ready to be refined and is extruded by means of the soap extruder. The extruded soap is
cut into required sizes. The cut bar soaps are ready to be stamped using manual soap press. Its
total cost is about Kshs. 200,000.
Fig. 3.2: Bar soap making machine front view
3.5.2. Small soap extruder
The soap making machine shown in figure 3.3 is also from Italy and is designed for a double
function. The first one is to mix the soap noodles, perfume and the color while the second one is
to extrude. The soap extruder gets a cooling system which allows it to work continuously without
a decrease in capacity. Standard model has a capacity of up to 100 kg/hr. at maximum output and
a diameter of 60 mm.
10
It has 2 options which are;
a) Adjustable screw speed (Electrical panel with frequency inverter to adjust the speed of the
screw from 10 to 35 rpm)
b) Special big cone. This special cone which has a maximum output of diameter 90mm was
studied to produce big soap bars.
Fig. 3.3: Small soap extruder
3.5.3. Small Soap Mixer
Fig. 3.4: Small soap mixer
11
The small soap mixer in figure 3.4 is designed to amalgamate soap noodles with colors and
perfume. The batch time can vary from 8 to 15 minutes depending on the color intensity of your
soap. The blades are designed with the same shape used in industrial soap manufacture.
There are 3 models: one manual 5kg batch soap mixer and two electric soap mixers for 15kg and
30kg batches
Small soap mixers technical data
Manual Soap mixer
Capacity: 5 kg/batch
Tank manufactured in stainless steel
Soap Mixers 15kg & 30kg
15kg model: Capacity: 15 kg/batch
15kg model: Installed Power: 0.75 kW
30kg model: Capacity: 30 kg/batch
30kg model: Installed Power: 1.1 kW
Tank manufactured in stainless steel
Industrial Gearbox with motor
Electrical panel with push buttons
Safety cover on the hopper with micro switch
Discharge by means of reverse tank
Electrical supply: 200/230/400V, 50/60 Hz
The cost of this mixer is Kshs 300,000
12
CHAPTER 4
DESIGN OF BAR SOAP MAKING MACHINE
4.1. SELECTION OF MATERIALS
When selecting the materials from which the different components of the bar soap making
machine is to be made, we first defined the requirements that are associated with its performance
when in service and with its manipulation into the shape of the product. The machine will work
at a speed of approximately 60rpm having been stepped down from the motor speed of 1400rpm.
The overall weight of the machine is optimum. This requires that the stands be able to hold that
weight for a long period.
Secondly, we obtained a balance between these requirements and the properties and other
characteristics of the materials that are available with regard to the economic considerations as
per the project objectives. The extrusion shaft, for example, could be made from carbon fiber
material but this is not used in this design due to the availability and cost of those materials.
Manufacturing methods contribute to the cost of the machine so while designing, we considered
parts that are easily and cheaply machined.
The main material chosen for the bar soap making machine is mild steel also known as plain-
carbon steel. It is the most common type of steel because its price is relatively small while it
provides material properties that are acceptable for many applications. Mild steel is used for the
housing and frame structures. It has the following properties:-
i) In mild steel composition, other than mild maximum limit of 0.02 carbons in the
manufacture of carbon steel, the proportions of copper and silicon are fixed while the
proportions of cobalt and chromium are not.
ii) A high amount of carbon makes steel different from other types of steel. Carbon
makes mild steel stronger and stiffer.
iii) Carbon atoms get affixed in the interstitial sites of the iron lattice and make it
stronger.
iv) Density is 7850kg/m3
v) Young's modulus is 207 GPa
These factors make steel be suitable as the main material of the bar soap making machine.
13
4.1.1. Pulley material
For the pulleys, the most preferred material is cast iron. This is chosen due to the following
properties,
i) Tensile strength – this is about 483Mpa.
ii) High resistance to deformation.
4.1.2. Toothed belt material
It is also known as timing belt. It is basically a flat belt with evenly spaced teeth in its inner
circumference. The teeth provide the advantage that a gear or chain drive possesses – positive
transmission of rotation and power. The timing belt consists of:
i) Steel wire or the tension member – This is usually a wire that takes up the load and
provides the reinforcement to the belt. The various materials that are used for the tension
member are steel wire and glass fibers.
ii) Base material (neoprene) – A good coat of neoprene is provided to the tension member in
order to prevent any damage to it by oil and moisture. It also acts as a wear resistor.
iii) Nylon coating – A film of nylon fabric coating is provided on the external layers of the
belt which provides a low co-efficient of friction for the surfaces that wear out quickly.
4.1.3. Extrusion shaft
The extrusion shaft is the main connection from the pulley to the die hence it should have the
following properties for it to work well;
i) High strength
ii) Good machinability
iii) Low notch sensitivity factor
iv) High wear resistant properties
For ordinary shafts, the material used is carbon steel of grades 40C 8 (selected), 45C 8, 50C 4
and 50C 12. The mechanical properties of these grades of carbon steel are given in the table 4.1
below:
14
British standard
designation
Ultimate tensile
strength, MPa
Yield Strength,
MPa
40C 8 560-760 320
45C 8 610-700 350
50C 4 640-760 370
Table 4.1: Mechanical properties of different grades of carbon steel
4.1.4. Materials of Hopper, Stand, Mixing tank and Extrusion shaft housing
All the above parts are made from mild steel of ultimate tensile strength of 44MPa and other
properties are tabulated in table 4.2
Mechanical Properties Metric
Hardness, Brinell( Kg/mm2) 126
Hardness, Knoop (Converted from Brinell hardness) (kg/mm2) 145
Hardness, Rockwell B (Converted from Brinell hardness) (kg/mm2) 71
Hardness, Vickers (Converted from Brinell hardness) (kg/mm2) 131
Tensile Strength, Ultimate 440 MPa
Tensile Strength, Yield 370 MPa
Elongation at Break 15.0 %
Reduction of Area 40.0 %
Modulus of Elasticity (Typical for steel) 205 GPa
Bulk Modulus (Typical for steel) 140 GPa
Poisson’s Ratio (Typical For Steel) 0.290
Machinability (Based on AISI 1212 steel. as 100% machinability) 70 %
Shear Modulus (Typical for steel) 80.0 GPa
Table 4.2: Mechanical properties of steel
15
4.1.5. Fastener Materials
Bolts and nuts in figure 4.1 for the bar soap making machine are made from carbon steel. Carbon
steel is the cheapest and most common bolt material. Most hardware stores sell carbon steel bolts
which are usually zinc plated to resist corrosion. The typical ultimate strength of this bolt
material is 379Mpa.
Fig. 4.1: Bolt and nut
4.2. SELECTION OF MANUFACTURING METHODS FOR PARTS
During the selection, we considered the size, shape of the components, required strength and the
material from which it is to be made. In addition to this, we looked at the economics of quantity
and cost, time allowed to manufacture the product and the locally and easily available
manufacturing tools and machines. Putting all the above into consideration led us into selecting
the best manufacturing method for each component.
The frames and mountings of the machine made from L-channels and square pipes and blocks
are simply machined. In this case, a power saw can be used to cut the parts into the required sizes
and shapes. This method is cheap and fast especially given the number of parts that are supposed
to be cut.
16
The extrusion shaft will be difficult to machine, time consuming and also a lot of wastage of
material from the parent material. Hence, the most preferred method of manufacturing will be
welding of shaft screw threads.
The extrusion shaft will be protected by a housing made of flat plate mild steel which is rolled
and welded together. The hopper is also welded to the housing to provide the feeding mechanism
to the extrusion shaft. The housing is also bolted and fastened to the extruder which also has its
own housing.
The die block could also be manufactured by casting. Various small components are held
together by welding since most of them cannot be made as a single component. This would make
the cost of fabrication by this method lower than that of casting. The motor and the variable
speed drive are bought.
4.3. DESCRIPTION OF PARTS OF DESIGNED BAR SOAP MAKING MACHINE
The design of the bar soap making machine has five major systems:
i) The power system
ii) Feeding system
iii) Extrusion system
iv) Cooling and Heating system
v) Soap exit systems
4.3.1. THE POWER SYSTEM
This provides the driving force for all the components of the machine. This system is composed
of the motor, pulley system and the variable speed drive.
4.3.1.1. Motor
The machine uses an AC motor with the following specifications:
i) 2 Hp
ii) 240 V
17
iii) 50 Hz
iv) 1400 rpm
Motors as shown in figure 4.2 can mostly be found in large supermarkets, electrical shops
and large hardware in the country.
Fig. 4.2: 3-phase AC Motor
4.3.1.2. Pulley system
This is composed of the belt drive and two pulleys. The rotary motion of the motor is transferred
to the extrusion shaft through the timing belt and two pulleys of the same diameter as shown in
figure 4.3 and 4.4, one at the motor shaft and the other at the extrusion shaft .The timing belt is
suited for the soap making machine for the following three main reasons:
i) Eliminates Slippage
Positive grip of belt teeth with "timing pulley" grooves eliminates slippage and speed
variation. There's neither initial stretch nor elongation to require belt take up because of
high modulus tension member.
ii) Less Bearing Load
Since the positive drive belt does not rely on friction; there is no need for high initial
tension. Thus, overhung bearing loads are reduced to minimum.
18
iii) Less Space
Small timing pulleys, short centers, narrow belts and high capacity can be combined to
reduce space requirements. Center distance can be permanently established.
Fig. 4.3: Timing belt
Fig. 4.4: Timing pulley system
19
The calculations on the timing belt and pulley are shown below
Total length of timing belt
� ℎ = � + + + −
Where − = 0
Fig. 4.5: Pulley and belt drive free body diagram
D1 – diameter of the driver pulley = 20cm
D2 – diameter of the driven pulley =20cm
L – Total length of the belt.
C - Distance between the center of pulley 1 and 2 = 35cm
� ℎ = � + +
= � + + ×
= 132.83 cm.
20
The thickness of the belt is 30mm as seen in the drawing of the pulley in the appendix. The
number of teeth as from the technical manual rubber timing drive table is 96.
(www.ageraab.se/uploads/categories81.pdf).
The number of teeth on each pulley is given by
Diameter of pulley = in 8�
Where n = number of teeth,
p = pitch = 0.03m
Diameter of pulley = 0.2m
= sin− . .
= 21 teeth.
4.3.1.3 Variable frequency drive
A variable frequency drive is a type of adjustable speed drive used in electro-mechanical drive
systems to control AC motor speed and torque by varying motor input frequency and voltage.
While there are a number of variations in variable frequency drive design; they all offer the same
basic functionality which is to convert the incoming electrical supply of fixed frequency and
voltage into a variable frequency and variable voltage that is output to the motor with a
corresponding change in the motor speed and torque. The motor speed can be varied from zero
rpm through to typically 100-120% of its full rated speed whilst up to 150% rated torque can be
achieved at reduced speed.
21
Fig. 4.6: Variable frequency working principle
The basic design consists of four elements as seen in figure 4.4 and explained below:
Rectifier: the working principle of rectifier is changing the incoming alternating current
supply to direct current.
Intermediate circuit: the rectified DC supply is then conditioned in the intermediate
circuit, normally by a combination of inductors and capacitors. It is used to smoothen the
pulsation included in the DC.
Inverter: the inverter converts the rectified and conditioned DC back into an AC supply
of variable frequency and voltage. This is normally achieved by generating a high
frequency pulse width modulated signal of variable frequency and effective voltage.
Control unit: the control unit controls the whole operation of the variable frequency
drive; it monitors and controls the rectifier, the intermediate circuit and the inverter to
deliver the correct output in response to an external control signal.
This variable frequency drive is typically 92-98% efficient with 2-8% losses being due to
additional heat dissipation caused by the high-frequency electrical switching and the additional
power required by the electronic components.
22
Equally motors connected to variable frequency drives experience some additional losses due to
heating caused by the high frequency electrical switching.
Electrically, a variable frequency drive is installed in series between the mains electrical supply
and the motor as in figure 4.7.
Fig 4.7 Connection of variable frequency drive to motor
The motor in use is a three phase synchronous with specification (2 Hp, 4 poles ). The required
frequency is set on the variable frequency drive vie a knob, it can be calculated using the
formulae; � =
Where N = speed required in rpm, f = frequency in Hertz
P = number of poles
To find the frequency, = � where p = 4 poles
= ×
= ��
23
Fig. 4.8: Small variable speed drive
The following are process control benefits are provided by the variable frequency drive:
Smoother operation
Acceleration control
Different operating speed for each process
Allow slow operation for setup purposes
Adjust the rate of production
4.3.1.4. The Mixer
There are a number of mixers available: handheld and machine type mixer. We will consider the
hand held paddle mixer as shown in figure 4.9 here as it is the economical, takes a small space
and is easy to control and clean up. Although a stand mixer can be used, it is more expensive and
hard to clean up.
Hand-held mixers generally consist of a metal shaft with paddles on one end that attaches to a
heavy-duty drill. Some manufacturers make shafts specifically for their driver while others offer
shafts that can be attached to a drill of the operator's choosing. Shafts are usually made of high-
strength steel and paddles are available in different shapes and sizes.
24
In mixing of the ingredients a paddle mixer is used whereby it is placed in a tank which houses
the mixing process. The prime object of this mixing operation is to coat each chip or noodle with
a small amount of the additives. Dispersal of the additives is effected by the noodles tumbling
and rubbing against each other so one with a high concentration of additives transfers it
to one with a lesser concentration. Over mixing will result in the breakup of the noodles and the
addition of too much liquid will cause clogging and inhibit the free movement of the noodles.
Fig. 4.9: Paddle mixer
4.3.1.5 Bearing
The bearing is located between the hopper and the belt drive to maintain separation between the
two components. This serves to reduce frictional resistance due to relative motion between
contact surfaces.
The standard dimensions of the diameters of the bearing in figure 4.12 used are: the outer
diameter is 20cm and the inner diameter is 8.05cm. The housing of the bearing is fixed to the
extrusion shaft housing through welding.
25
Fig. 4.10: Bearing
It should be lubricated in order to reduce friction and wear between the sliding parts. The
lubrication process forms part of the regular maintenance measures and oil or light grease is used
for this purpose.
4.3.2 THE FEEDING SYSTEM
4.3.2.1 Hopper
A hopper is a large pyramidal shaped container used in industrial processes to hold particulate
matter as shown in figure 4.13. Hoppers are usually installed in groups to allow for a greater
quantity collection. Most hoppers are made of steel.
However, in this design we are using a hopper for the collections of soap noodles from the
mixing tank. The hopper receives soap noodle from the mixing tank and it is positioned at 33
centimeters from the belt drive. The hopper is made of mild steel and has a total volume of
8860.3692 cm3.
26
Fig. 4.11: Hopper
Fig. 4.12: Free body diagram of a hopper
� = � = =
Tan � = � ; = �an �
27
X = an ° = 12.988 cm
b = 36 – (12.988 × 2) = 10.024cm
a = 30 – (12.988 × 2) = 4.024cm
Volume of the hopper, V = � (� + � + √� × � )
A1 = L × W
= 1080 cm2
A2 = ×
= 40.3366cm2
Thus; V = ( + . + √ × . )
= 8860.3692cm3
4.3.3 THE EXTRUSION SYSTEM
The soap extruder is designed for a double function. The first one is to homogenize the mixture
of soap noodles, perfume and color coming while the second one is to extrude the ready to cut
soap. It is a definite advantage to have a variable speed facility for the extruding operation both
to influence the finished appearance of the extruded soap and to control the rate of production.
Extruding plodders can be provided with refining heads which can be inter-changed with the
extruding head so that only a single plodder is required for the two operations.
An extrusion process for the production of a solid soap product comprises feeding a soap
composition into an extruder having a housing with an inlet and an outlet and a screw thread
28
traversing the extruder, wherein at least a portion of the housing from the inlet to the outlet of the
housing is tapered to form a portion of the housing with a reduced cross-sectional area and the
screw thread extends at least partly into the tapered portion of the extruder where the screw
thread ends and extruding the soap composition through the extruder.
As the soap noodles move through the extrusion shaft, a torque is generated due to the forces
incurred. This torque is calculated as:
T = � �� �
Where: power=1492watts (1 horse power=746 watts)
T = torque (N. m) ɷ=angular speed (rad/s)
= × × �
= 237.4 Nm
(http://www.pumpsandsystems.com/topics/motors/relationship-torque-and-shaft-size.)
29
The extrusion shaft is made up of a mild steel solid shaft with spiral screw all over its length and
a cone on its rear end. The geometry of a double-flighted screw and its nomenclature are
presented in the figure below.
ϴ(r)
Fig. 4.13: Screw thread free body diagram
Several of the screw geometric parameters are easily obtained by observation and measurement
including the number of flight starts, inside barrel diameter, channel depth, lead length, flight
width and flight clearance. The number of flight starts, n, for the geometry in Fig. 4.15 is two.
The inner diameter of the barrel is represented by Db, and the local distance from the screw root
to the barrel is H. The diameter of the screw core is represented by Dc. The mechanical clearance
between the land of the screw flight and the barrel is λ. The mechanical clearance is typically
very small compared to depth of the channel. The lead length, L, is the axial distance of one full
turn of one of the screw flight starts. This is constant in each section of the screw. The flight
width at the tip of the screw and perpendicular to the flight edge is e.
Dc
B b
L �
H
Db
30
The remaining geometrical parameters are easily derived from the measured parameters
presented above. Several of the screw parameters are functions of the screw radius. They include
the perpendicular distance from flight to flight, W(r), the width of the flights in the axial
direction, b(r) and the helix angle, θ(r), the angle produced by the flight and a plane normal to
the screw axis. At the barrel wall these parameters are subscripted with a b. The helix angle at
the barrel wall is θb and is calculated using Eq. 1.1. The helix angle at the barrel wall for a
square-pitched screw is 17.7°.
tan ϴb = ��� thus ϴb = arctan =
���
Eq.1.1
= �
= 20°
The relationship between the width of the channel perpendicular to the flight at the barrel
(housing) interface, Wb, and the axial distance between the flight edges at the barrel interface,
Bb, is as follows:
Wb = Bb cos ϴb = � − �b =
� � − e
e = bb cos ϴb
The geometric parameters are a function of the radial position (r) of the screw. It includes the
helix angle and the channel widths. The length of an arc for one full turn at the barrel surface is
πDb. At the screw surface the length of the arc for one turn is π (Db – 2H). The lead length,
however, remains the same. This leads to a larger helix angle at the screw root than at the barrel
surface.
31
The helix angle and the channel widths at the screw core or root are designated with a subscript
c, and they are calculated as follows: tan � = �� �− � = ���
Thus � = tan− ��� ;
= 32.38 °
Thus the screw has a narrower normal distance between flights at the screw root because the
helix angle is larger while the lead remains the same.
Wc = Bc cos � = �� − cos � =
�� cos � −
e = bc cos �
= 6.7485 - 0.9397 = 5.8088cm
The average channel width is used for many of the calculations. This average channel width is
represented as simply W here and is calculated using Eq. 1.1.
W = +
= . + .
= . cm
The 3-dimensional view of the soild shaft screw conveyor is shown below in figure 4.16.
32
Fig. 4.14: Screw thread
Parameter Values
Barrel diameter, Db 14cm
Core diameter, Dc 8cm
Lead length, L 16cm
Meter channel depth, H 3cm
Flight width, e 0.9397cm
Flight start, n 2
Helix angle at the barrel, �b 20°
Helix angle at the screw core, �c 32.5°
Channel width at the barrel, Wb 6.5778cm
Channel width at the core, Wc 5.8088cm
Average channel width, W 6.1933cm
Channel aspect ratio, H/W 0.4844
Table 4.3: Measurements of the screw thread
33
The capacity of a screw conveyor depends on the screw diameter, screw pitch, speed of the
screw and the loading efficiency of the cross sectional area of the screw. The capacity of a screw
conveyor with a continuous screw:
Q = V * ρ
Q = 60 * (π/4) * D2 * S * N * ψ * ρ * C
Where,
Q = capacity of a screw conveyor
V = Volumetric capacity in m3/hr.
ρ = Bulk density of the material, kg/m3
D = Nominal diameter of Screw in m
S = Screw pitch in m
N = rpm of screw
Ψ = Loading efficiency of the screw
C = Factor to take into account the inclination of the conveyor
Parameters
Screw Pitch:
The screw pitch taken is equal to the diameter of the screw, D.
Rpm of Screw:
The usual range of rpm of screw is 10 to 165. It depends on the diameter of screw and the type of
material.
Loading efficiency:
The value of loading efficiency should be taken large for materials which are free flowing and
nonabrasive while for materials which are not free flowing and or abrasive in nature the value
should be taken low.
Ψ = 0.12 to 0.15 for abrasive material
= 0.25 to 0.3 for mildly abrasive material
= 0.4 to 0.45 for nonabrasive free flowing materials.
34
Inclination Factor:
The inclination factor C is determined by the angle of screw conveyor with the horizontal and is
given in the table below.
Table 4.4: Inclination factor
Therefore the value of;
D = 0.14 m
S = 0.08m
N = 60 rpm
Ψ = 0.12
ρ = 880 kg/m3
C = 0.65
� = × � × . × . × × . × × .
= 304 kg/hr.
Therefore the machine design has an output of 304 kg/hr.
4.3.4. COOLING AND HEATING SYSTEM
4.3.4.1. Cooling system
The cooling system is basically water around the mid-section of the extrusion shaft. A water bath
is fitted around the extrusion shaft but without it coming into contact with the shaft or the soap.
Water is contained in a cylinder with inlet and outlet pipes where cold water from a tank
(reservoir) placed at a higher level enters and warm water leaves through the exist pipe fixed at
the bottom of the container.
Heat generated by the operation of the shaft (extrusion) is conducted to the cold water since the
material making the housing of the extrusion shaft is mild steel which has good thermal
Angle of the screw with the horizontal
0°
5°
10°
15°
20°
Value of factor C
1
0.9
0.8
0.7
0.65
35
conductivity properties and then transferred out. For normal operation, the screw ought to
operate at an optimum temperature of 38− C .Therefore the circulating water during operation
maintains this range of temperature. If the temperature goes beyond optimum, then the shaft will
be hindered by thermal fatigue. Most failures of extrusion shaft results from this. High
temperatures also activate corrosion in the extrusion shaft housing.
4.3.4.2. Heating system
Heating system is fixed around the tip of the extrusion shaft cone. An immersion electric heater
is fitted inside the barrel (water jacket) where water is heated to make the soap smooth and
compact before it is extruded.
The immersion heater is automated by a thermostat which controls the temperature to optimum.
The electrical heater has an electrical device that converts electrical current to heat. The heating
element inside the heater is an electrical resistor. The set point temp is usually ℃ − ℃ .
The thermostat operates by switching the immersion heater off/on when temp falls below
optimum.
4.3.5. BAR SOAP EXIT SYSTEM
This system is composed of a rectangular die block. This makes the soap to be rectangular taking
the shape of the die. The die block is firmly fitted at one end immediately after the edge of the
extrusion shaft. Surrounding it is a bath of warm water which warms and softens the exiting bar
soap.
4.3.5.1. Properties of the die block material
The die material must have certain properties in order to withstand the stresses during operation.
These properties include thermal expansion and modulus of elasticity, mechanical properties,
resistance to thermal fatigue and chemical stress of die.
4.3.5.2. Thermal expansion and modulus of elasticity
At smaller thermal expansion and modulus of elasticity, the stress at a certain thermal impact is
smaller. It depends on modulus of elasticity of elementary metal that is only a little changed by
alloying.
36
Table 4.5: Properties of materials (https://en.wikipedia.org/wiki/Die_casting)
The selected material is low alloy heat treated steel due to its desirable properties. It is also easy
to cast in the workshop and affordable.
4.3.5.3. Die life
Die life is a major concern for the bar soap making industry. Die cracking and wear are the major
setbacks. Improving die life by avoiding premature die failure due to cracking is one of the
dominating challenges that die and forging engineers face.
Die life can be significantly improved by pre-shape produced in the blocker stage. This is
achieved by removing excess material. When the soap is passing through the die, high tensile
stresses are experienced by the die material.
The life span of the steel made die can be described by cyclic loading (S-N) curves. These curves
are obtained by plotting the magnitude of the cyclic stress(S) against logarithmic scale of cycles
to failure (N). The soap plodder operates under low stresses hence the material can withstand an
infinite number of loads that is, the stresses will always be below the endurance (fatigue) limit at
about one million load cycles.
Material Addition Modulus
of
elasticity
(MPa)
Coefficient of
thermal
expansion
(×10-6
)m/mK
Thermal
conductivity
W/mK
Hardness
kg/mm2
Resistance
against
melting
Copper - 105000 16.5 0.383 60 excellent
Beryllium 0.5 Be 110000 11.5 0.0836 400 Excellent
Heat treated
soft steel
0.4 C
220000
11.7
0.0627
8
Excellent
Low alloy
treated steel
0.3 C
215000
10.5
0.0418
350
excellent
High alloy
treated steel
0.3 C, Cr,
W
210000
13
0.0188
400
excellent
37
Chart 4.1: S-N curve
4.3.5.4. Die dimensions
The die dimensions will determine the dimensions of the bar soap, i.e. breath (B) and height (H).
The standard size of most bar soaps is B=6cm and H=3cm. The die should have similar
dimensions but with smaller tolerance (allowance). For tolerance of +0.05cm, B=6.05cm and
H=3.05cm. The tolerance allows the soap to have exact dimensions as per the given standards.
The length of the bar depends on the wish of the customer. Most of the bar soaps in the market
are approximately 0.5mand weigh between 800-1000g.
4.3.6 MACHINE FIXTURE SYSTEM
This comprises of the mountings and stands made of mild steel to hold the machine in position.
It should also be able to hold against the vibrations that occur during the process of extrusion.
Figure 4.16 shows stands that are made of square tubes to minimize the weight.
38
Fig. 4.15: Square tube
4.4. WORKING PRINCIPLE OF THE BAR SOAP MAKING MACHINE
The bar soap making machine uses a motor which when started rotates the extrusion shaft
connected to it through a toothed timing belt and a pulley drive. This motor is connected
electrically to a variable speed drive which steps down its speed from 1400 rpm to the required
speed of 60 rpm. The extrusion shaft has bearing at its rear end to ensure that it is always in line
and minimize friction. The extrusion shaft has spiral screws with lead length of 16cm.
The soap noodles are made in a separate tank by mixing the various ingredients and chemicals
using a mixer. The noodles at a high temperature therefore you have to give them time to cool
and dry .Once the noodles are ready you pour them into the hopper directly above the extrusion
shaft at the rear end (near the pulley system). As the extrusion shaft rotates, it pushes the soap
noodles towards the die block. The soap noodles get into the space between the spiral screws
where they are compressed as they rotate to make them compact before reaching the exit system.
Apart from the opening for the hopper, the rest of the extrusion shaft is enclosed in a mild steel
housing. This housing has a heater that has a thermostat placed just before the die block to heat
the water jacket.
After being compressed up to the right compactness, the soap exits the bar soap making machine
through the die block. The bock has width of 6.05cm and height of 3.05cm in order to produce a
bar soap of the standard measurement of 6cm by 3cm. A table is placed in line below the die
block. The bar soap slides on this table where it is cut into the required length. The standard
length is usually 50cm. The size of the bar soap produced can be altered by changing the
dimensions of the die block.
39
CHAPTER 5
DETERMINATION OF TECHNICAL AND ECONOMIC VIABILITY
5.1. TECHNICAL VIABILITY OF BAR SOAP MAKING MACHINE
In the analysis of the bar soap making machine in terms of technical viability, we took into
account factors such as performance, environmental factors, maintenance, aesthetics/ergonomics,
size and weight and safety. These are outlined below:
5.1.1. Performance
In Kenya, electrical power is supplied at a rating of 240V, 50Hz. The bar soap making machine
will use a motor of 2Hp and 1400rpm. From this and a variant for speed reduction, the machine
will operate at a rate of 60 revolutions per minute to produce 304kg of soap per hour.
The bar soap making machine is designed to run continually for 12 hours. The bearing is well
lubricated to reduce friction. With adequate lubrication, there is minimal friction on the
components leading to minimum heat generation. The bar soap making machine is designed to
produce a rectangular shaped soap whose standard length is 50cm.
5.1.2. Environment
The bar soap making machine can operate indoors and outdoors under normal working
conditions. A motor insulation and protection is required to ensure that there is no sparking or
arcing during operation due to the vibrations that are experienced during the operation of the bar
soap making machine.
5.1.3. Maintenance
Frequent lubrication of the bar soap making machine should be carried out. In addition to this
general observation should be made to ensure that all the joints, bolts and nuts are well secured.
For the above bar soap making machine innovation, maintenance takes a short time since it is
smaller and most parts can be easily accessed.
40
5.1.4. Aesthetics
The bar soap making machine is painted in blue to give it a fine finish. The color can also change
according to customer specification.
5.1.5. Safety
A guard is installed around the pulley system to prevent any injury that may arise. All metal
edges are also blunted out to prevent cuts and bruises.
5.2. ECONOMIC VIABILITY OF THE BAR SOAP MAKING MACHINE
With the objective of designing a bar soap making machine suitable for the soap industry in
Kenya, it is of paramount importance to get a machine which can be fabricated locally. From the
available materials and manufacturing methods, we chose cheap but appropriate combinations in
order to get the most economically viable design.
Considerations put in place in the design and choice of materials for the various parts of the bar
soap making machine included the type, direction and operating speed, machinability and
castability of the part material, cost of material and fabrication, material property and aesthetics.
With the above total cost of manufacture of the bar soap making machine, it would be affordable
for the soap industry as opposed to the imported machines. It would in turn lead to a reduction of
bar soap retail prices which would improve the competition from imported bar soaps.
Mass production of this machine would further lead in the lowering of the cost of production due
to the benefit of economies of scale.
41
CHAPTER 6
CONCLUSION AND RECOMMENDATIONS
6.1. CONCLUSION
The current design of the bar soap making machine has overall dimensions of 1350mm length,
500mm width and the total height 920mm. Focus is laid on the reduction of the bulk and overall
price of the machine without compromising on the quality of the bar soap produced.
To achieve this, the working mechanism of the bar soap making machine is designed so that the
total number of moving parts is reduced to a necessary few. All motion of the bar soap plodder is
conveyed from the motor to the extrusion shaft through a pulley system. This modification aided
by sufficient lubrication of the machine has also rendered the machine to be adequately water
cooled.
Careful selection of materials observed while considering their availability without
compromising on the durability of the bar soap making machine once it is fabricated. On the
subsequent implementation of the above design, the cottage industry will tend to develop having
introduced a business opportunity. This is a blue ocean venture that will enable not only the
creation of jobs but will also, in line with vision 2030, boost the Kenyan economy. This would
also come by way of reducing the cost of bar soap.
This project is also aimed at cutting down the prices of bar soap making machines which are
imported. By introducing this cheap and economical bar soap making machine into the Kenyan
market, there would be competition with the imported machines and this would eventually lead
to the reduction of bar soap prices. As is evident from the cost analysis of the bar soap making
machine, it is much cheaper than the existing bar soap making machines and can be
manufactured locally from the available materials.
Operation of the machine is possible under normal conditions as experienced in workshops.
Ingress of dust should be avoided by maintaining a clean working environment. This gives
longer service life for the motor and eventual reduction in the cost of production. This bar soap
making machine is found out to be economically viable as analyzed above. Its implementation
42
has the potential of promoting the manufacturing industry in Kenya along with the creation of
employment opportunities for the Kenyan people.
6.2. RECOMMENDATIONS
The bar soap making machine innovation can produce bar soap of between 6cm by 3cm and 8cm
by 4cm. There is, however, a need for bar soap of other different sizes so there should be an
innovation to this effect.
43
REFERENCES
1. Khurmi, R. S. (2004). A Textbook of Machine Design (14th Edition) Eurasia Publishing House
(PVT) LTD.
2. Micheal Ashby, Hugh Sherdiff and David Ceba (2007) Material Engineering Science
Processing and design.
3. George E. Dieter, (1988) .Mechanical Metallurgy SI Metric Edition. McGraw-Hill Book
Company
4. William D. Callister, Jr and David G.Rethwisch, (2010) Materials Science and Engineering an
Introduction – 8th edition. John Wiley & Sons. Inc
5. Cavitch, Susan M. The Natural Soap Book (1995): Making Herbal and Vegetable-Based
Soaps. Storey Communications.
6. Maine, Sandy. (1995) the Soap Book: Simple Herbal Recipes. Interweave Press
7. http://www.madehow.com/Volume-2/Soap.html#ixzz3xmlMbeb7
8. https://cosmeticskenya.wordpress.com/2014/09/16/bar-soap-business-in-kenya-2/
9. http://www.madehow.com/Volume-2/Soap.html
10. http://www.detergentsandsoaps.com/articles/bar-soap.html
11. www.ageraab.se/uploads/categories81.pdf
12. http://www.pumpsandsystems.com/topics/motors/relationship-torque-and-shaft-size
13. www.hanserpublications.com/.../9781569904480_SAMPLE%20C..
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APPENDICES
APPENDIX 1: COST EVALUATION OF THE BAR SOAP MAKING MACHINE
No.
ITEM
MATERIAL
QUANTITY
COST PER
(Kshs)
TOTAL COST
(Kshs)
Kg
Unit
1. Motor 1 10,000 10,000
2. Pulley Cast Iron 2 500 1,000
3. Pulley Guard Mild steel 1 500 500
4. Variable Speed
drive
1 6,000 6,000
5. Mixer 1 10,000 10,000
6. Bearings Aluminum 1 100 100
7. Hopper Mild Steel 1 700 700
8. Extrusion shaft Mild Steel 1 12,900 12,900
9. Extrusion Shaft
housing
Mild steel 1 1,000 1,000
10. Frame
Mounting
Mild steel 20 400 8,000
11. Mixing tank Mild Steel 1 7,000 7,000
12. Die Block Cast Iron 1 7,500 7,500
13. Bolts and Nuts Alloy Steel 15 70 1,050
14. Timing Belt Rubber 1 1,200 1,200
15. Immersion
Heater
1 3,500 3,500
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16. Fatty Acid 5kg 1,000 5,000 5,000
17. Perfume 50grams 500 500 500
18. Distilled water 15liters 250 3,750 3,750
19. Oil soluble 5liters 80 400 400
20. Sodium silicate 10kgs 200 2,000 2,000
21. Kaolin Powder 6kgs 1,000 6,000 6,000
22. Sodium
hydroxide
10kgs 500 5,000 5,000
23 Paints 5litres 200 1,000 1,000
24. Brush 2 100 200 200
25. Labor 16,000 16,000
26. Miscellaneous 5,000 5,000
TOTAL 115,300
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APPENDIX 2: DRAWINGS
BLOCK DIAGRAM OF THE HOUSING AND HOPPER
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THE HOPPER
48
BLOCK DIAGRAM OF BAR SOAP MAKING MACHINE
SIDE VIEW
49
FRONT VIEW
50
TOP VIEW
51
HOUSING AND PLODDER
52
DIFFERENT VIEWS OF THE HOUSING AND HOPPER
53
SCREW CONVEYOR AND ITS DIMENSIONS
54
DIFFERENT VIEWS OF THE TIMING PULLEY
55
TIMING PULLEY BLOCK DIAGRAM
56
BEARING
57
SOAP PLODDER FROM KIRDI
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SOAP PLODDER FROM Kenya Industrial Research & Development Institute (KIRDI)