New feature of semi-automatic injera making machine consists batter delivery, polishing, batter dispensing, cutting and rolling mechanism. The connecting rod pushes the cover downward direc-tion, as a result the rotating plate inside the cover polishes the pan. The previous injera making machine were huge and very expensive but this product reduces cost and size of the previous automatic machines.

1. ADDIS ABABA UNIVERSITY
ADDIS ABABA INSTITUTE OF TECHNOLOGY
SCHOOL OF MECHANICAL AND INDUSTRIAL ENGINEERING
Prepared by: Milion Workineh----------ATE/3564/09
Inst: Dr. Haileleoul Sahle.
January 28, 2022
Product Design and Development (Meng-4342)
Semi-automatic Injera Baking, Rolling & Cutting Machine

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Contents
Chapter 1...................................................................................................................................... 6
1.1. Introduction......................................................................................................................... 6
1.2. Statement of the Problem..................................................................................................... 7
1.3. New Features of Semi-Automatic Injera Making Machine.................................................. 8
1.4. Mission statement ................................................................................................................. 8
Description of the product .................................................................................................. 8
Key business goal ............................................................................................................... 9
Target market...................................................................................................................... 9
Primary market ................................................................................................................... 9
Secondary market ............................................................................................................... 9
Assumptions and constraints .............................................................................................. 9
Stakeholders........................................................................................................................ 9
Chapter 2.................................................................................................................................... 10
Identifying Customer Needs ...................................................................................................... 10
2.1. Introduction......................................................................................................................... 10
2.2. Identification Of Customer Need........................................................................................ 15
2.2.1. Gather raw data from the customer ........................................................................ 15
2.2.2. Interpreted customer need....................................................................................... 15
1) Identification of need: ........................................................................................................... 16
a) Needs the development of this product missed ..................................................................... 16
b) Why weren’t these needs met?.............................................................................................. 17
c) Did the developers deliberately ignore these needs? ............................................................. 17
Chapter 3.................................................................................................................................... 18
Product Specifications ............................................................................................................... 18
Introduction................................................................................................................................ 18
3.1. Need Statement.......................................................................................................... 18
3.2. Prepare the list of metrics ....................................................................................... 20

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3.3. Collect competitive benchmarking information. ....................................................... 21
3.4. Ideal and marginally acceptable target values. ......................................................... 28
Chapter 4.................................................................................................................................... 29
Concept Generation ................................................................................................................... 29
4.1. Clarification of the problem................................................................................................ 30
4.2. Search Externally................................................................................................................ 31
4.2.1. Interview lead users ................................................................................................ 31
4.2.2. Patent search........................................................................................................... 31
4.3.1. Brainstorming ......................................................................................................... 32
4.3.2. Graphical and physical media................................................................................. 32
4.4. Exploring systematically .................................................................................................... 32
4.5. Concept Decomposition...................................................................................................... 33
Chapter 5.................................................................................................................................... 35
Concept Selection...................................................................................................................... 35
Introduction................................................................................................................................ 35
Concept screening...................................................................................................................... 35
1. Prepare the selection matrix.......................................................................................... 35
2. Rate the concepts .......................................................................................................... 35
3. Rank the concepts ......................................................................................................... 35
4. Combine and improve the concepts.............................................................................. 36
5. Selection one or more concepts .................................................................................... 36
6. Reflect on the results and the process........................................................................... 36
i. Ranking for baking mechanism................................................................................ 38
ii. Ranking for rolling mechanism.................................................................................... 40
iii. Ranking for cutting mechanism .................................................................................. 41
Chapter 6.................................................................................................................................... 43
Concept Testing......................................................................................................................... 43
Chapter 7.................................................................................................................................... 44

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Product Architecture.................................................................................................................. 44
Introduction................................................................................................................................ 44
Step 1: Creating a schematic of the product .............................................................................. 45
Step 2: cluster the elements of the schematic ............................................................................ 45
Step 3: Create a rough geometric layout.................................................................................... 45
Step 4: Identify the fundamental and incidental interactions .................................................... 45
Design concept........................................................................................................................... 46
Design For Manufacturing......................................................................................................... 50
Economic Analysis .................................................................................................................... 52
Bill of material.................................................................................................................. 52
Conclusion................................................................................................................................. 54
Acknowledgement ..................................................................................................................... 55
Reference ................................................................................................................................... 56
List of tables
Table 1:Customer need identification1 ............................................................................................. 12
Table 2:Customer need identification 2 ............................................................................................ 12
Table 3:Customer need identification 3 ............................................................................................ 13
Table 4: Customer need identification from operator ....................................................................... 14
Table 5:Customer data template filled in with sample customer statements & interpreted need. .... 16
Table 6: Level of performance.......................................................................................................... 18
Table 7: Level of importance in association to for the customer needs. ........................................... 19
Table 8:List of matrixes for Sem- automated injera baking machine............................................... 20
Table 9:The needs-metrics matrix..................................................................................................... 20
Table 10; Competition of bench mark............................................................................................... 28
Table 11: Ideal and marginally acceptable target values. ................................................................. 29
Table 12: Weight for each selection criteria out of 100%................................................................. 37
Table 13: Performance rating............................................................................................................ 37
Table 14: Concept scoring for semi-automatic injera making machine............................................ 38
Table 15: Weight of performance ..................................................................................................... 39

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Table 16: Concept scoring for semi-automatic injera making machine/ ranking of rolling mechanism
................................................................................................................................................................ 40
Table 17: Concept scoring for semi-automatic injera making machine/ ranking of cutting mechanism
................................................................................................................................................................ 41
Table 18: Quality function deployment ............................................................................................ 42
Table 19: Bill of material .................................................................................................................. 53

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List of figures
Figure 1: Wass injera mitad .............................................................................................................. 21
Figure 2: Automatic mitad for small scale (Wassei Mulugeta injera baking machine) .................... 22
Figure 3: Shega mitad ....................................................................................................................... 22
Figure 4: Gel good fully automatic injera baking machine............................................................... 22
Figure 5: Zelalem semi- automatic injera baking machine............................................................... 23
Figure 6; The Injerama machine ....................................................................................................... 23
Figure 7: Conventional (Traditional) electric mitad ......................................................................... 24
Figure 8: Conventional (Mirt mitad (lakech) .................................................................................... 24
Figure 9: Five step methods of concept generation........................................................................... 30
Figure 10: Concept classification tree power of source .................................................................... 32
Figure 11: Concept classification tree of cutting mechanism ........................................................... 32
Figure 12: Concept classification tree of rolling mechanism............................................................ 32
Figure 13: (a) black box, (b) functional decomposition of semi-automatic injera machine. ............ 33
Figure 14:Functional decomposition diagram for the rolling and cutting injera machine................ 34
Figure 15: Concept generation of baking machine ........................................................................... 34
Figure 16: sketch of Injera baking system in design concept ........................................................... 48
Figure 17: the top view of design concept by auto cad ..................................................................... 48
Figure 18: 2D semi- automated injera baking machine design by auto cad ..................................... 49
Figure 19:collecting system using fast return mechanism ................................................................ 49
Figure 20:Solid model of single part of semi-automatic Injera baking machine. ............................. 49
Figure 21: Break even analysis for semi-automatic injera baking machine graph ........................... 53

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Chapter 1
1.1. Introduction
In Ethiopia, since one of the most popular foods is injera, the average people eat it two to three times
a day. It is perhaps consumed by over 50 million people, the majority people, on a daily basis in virtually
every household. So, it is an issue that should be raised to improve the day-to-day life style of the people.
[Van Buskirk, R., Haile,T. and Ezana,N. “The Effect of Clay and Iron Cooking Plates on Mogogo
Efficiency and Energy Use: Experimental Results”] Preparing injera requires considerable time,
resource and material. In the ancient time, Ethiopians used stone to bake muffin and bread which is the
most wanted food. It was made from stone before the discovery of clay sand pan. Gradually the clay pan
is developed and modified its material and shape as the time past. Later on, Injera could be baked using
black clay plate of diameter 50-60 cm called Mitad in (in Amharic) or Mogogo (in Tigrinya) which is
placed over a three stone or on specialized electric stove.
To make this injera they are used a variety of cooking procedures. When a fermented dough poured
on a hot clay pan and stayed until the boiling temperature reached; bubbles, from the surface of uncooked
injera, escape forming thousands of tiny craters (eyes) that give the peculiar Injera texture.
Before the invention of electric ‘mitad’, Ethiopians use biomass, including fire wood, cow dung
(locally called kubet), leaves, crop residues, saw dust etc., As a source of energy to make ‘injera’, still
in rural areas people use them, especially wood, which are time consuming and weakening. Injera baking
practice is the most energy intensive activity in Ethiopia and is similar all over the country with a slight
difference in pan dimension and stove efficiency. Injera baking requires over 50 % of the primary energy
consumption and over 75 % Households’ energy consumption. This intensive biomass utilization is
accounted for deforestation, expensive fire wood price and poor kitchen environment. [World Bank
report, Household Cook stoves, Environment, Health, and Climate Change a new look at an old problem,
2011].
The baking process is the same with the traditional way of baking except the source it uses is electric,
but still, it has no change on the production. That is, if there is sufficient amount of electric power the
production time will be the same with traditional time. Otherwise, it is too slow.
These all were/are being done within a lot of energy consumption, high labor cost, time, low production.
So, as an engineering point of view or perspective these drawbacks should be minimized.
Then, the aim of this paper is to design and analyze the performance characteristics and efficiency of
the electric Injera baking pan /mitad/, and to increase the production with the same time required per
Injer and minimum running production cost using electric source i.e., new and improved with low energy
and high production rate, Injera making mitad, which we, the designers, call it SEMI-AUTOMATIC
INJERA BAKING MACHINE.

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1.2. Statement of the Problem
Ethiopia is one and only country that mostly make injera and exports it to foreign countries, as a
result it is easy to understand the role of injera making machine. Especially traditional mitad which are
widely used having clay soil are used to bring loads and consume electricity. Due to this it is very
important to manufacture highly competitive and convenient machine to our country. The advantage of
using automated ‘injera’ making machine is not only reducing workers load but also saves time,
minimizing electric consumption. Unfortunately, there are no companies or individual that produce
automated injera making mitad in Ethiopia. Accordingly, to overcome this problem and to maximize
and preserve the above-mentioned advantages we must produce automated mitad with better quality and
performance. Therefore, we choose to analyze the design, material selection and manufacturing process
of locally manufactured electric mitad, in order to identify problems related with domestically
manufactured mitad and to come out with possible recommendation and that is going to be highly useful
for our country in the future.
Electric ‘mitad’ we are using now a days consumes more electric power and time, and as such it needs
to be modified to a newer version that goes with the world’s current technology and development, “save
time save energy!”. In the making of Ethiopian ‘injera’ somebody must stand by the electric ‘mitad’ all
the time to bake and to take out the cooked ‘injera’, both needs a special skill, which could be more time
consuming and it can lead to major discomfort and weakening to the person working on it.
Time loss is occurred due to time gap between successive operations such as between spraying the
batter and the batter on the mitad until it is sealed over, between uncovering the mitad for temperature
drop and taking it out the cooked injera, between sweeping the mitad and spraying the batter to the mitad
and so on have delay of time.
Energy loss is the main loss formed in the baking process of injera. Much amount of electrical energy
might be lost because of the absence of temperature sensor, heat loss in thw form of steam during
uncovering, energy lose due to a proper coating.
For only one injera mitad one operator who is skilled at baking (like at rotating, temperature leveling,
timing and taking out) is required. So, for many injera mitads in production area many specific operators
are also needed with expected tiredness for more production.
Consequently; summing up all problems listed above will increase running cost of injera. ‘injera’
making process that is more efficient and productive will be required for personal or industrial use to
improve time and energy usage. In order to do this, a mechanism and energy saving system is
recommended to be included into the electric ‘mitad’. Generally, these main problems (time loss, energy
loss, excess electric power usage and the danger for the person operating from electric shock or worst
and his/her tiredness) are to be minimized. And my design can minimize these problems and greatly

9. 8 | P a g e
assist our local or foreign community in providing semi-automatic injera baking machine that will ease
the manual injera baking system.
1.3. New Features of Semi-Automatic Injera Making Machine
New feature of semi-automatic injera making machine consists batter delivery, polishing, batter
dispensing, cutting and rolling mechanism. The connecting rod pushes the cover downward
direction, as a result the rotating plate inside the cover polishes the pan. When the cover further
pushes the pan, the spring under the pan stores energy and when released, the spring creates
vibration. So that the batter delivered over the pan will be dispensed. The bottle which is located
over the cover uses gravity to deliver the batter through solenoid valve which is located inside the
cover.
Unlike others this design uses indirect method to spread the batter over the pan rather than using
direct contact method like rotating plate over the pan. So that this helps to produce quality injera
with its bubble texture on top side. The previous injera making machine were huge and very
expensive but this product reduces cost and size of the previous automatic machines.
1.4. Mission statement
In order to provide guidance for the development team, the mission statement for semi-automatic injera
making machine is formulated as follow:
In the mission statement we will discuss the following points;
 Description of the product
 Key business goal
 Target markets
 Assumption and constraints
 Stakeholder
Description of the product
Semi-automatic injera making machine with batter delivery and dispensing mechanism.
Now adays people are focusing on making an automatic machine that produce injera, that is without the
needs of people. But all of them needed a human labor at the packing stage. IN this product design, It
will be implemented at the end of the baking machine and will roll and dice it into packable sizes. Even
a packing machine can be continued next to the roller, this will make it fully automatic without need of
labor.

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Key business goal
 To minimize the overall running cost of injera,
 To analyse the performance characteristics and efficiency of the electric Injera baking pan
/mitad/,
 To increase the rate of production of injera per time,
 To minimize running production cost
 To discuss the past, present and resent situation of injera baking technology and alternative
practices in Ethiopia,
 To make the injera baking process safer from hygienichealth point of view,
 To make design and analysis for components that would be incorporated in the generalized
system of the selected injera baking machine,
Target market
Primary market
 Organization that masses product injera.
 family households.
Secondary market
 Hotel and restaurants
 Organization that exports injera.
 Campus student cafe
Assumptions and constraints
 Easy to use and maintain
 Eco-friendly to environment
 Efficient and effective
 Manufactured using simple/local resource
Stakeholders
 Product designers and developers.
 Organization that product machine.
 Organization that product injera.
 user, shareholder, manufacturer, distributer and reseller.

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Chapter 2
Identifying Customer Needs
2.1. Introduction
The design of a product is focuses mainly on customer needs. One of the necessary procedures of design
of a product is the customer need identification.
1. Raw data gathering from customers
Direct observation of the product in use
We have been able to notice the following limitations on the existing semi-automatic Injera making
machine and Injera rolling /cutting machine;
Name: --------------------- occupation:
Address: ---------------- telephone No.
Customer need identification guide line Response
1 Are there semi-automatic Injera making machine user in you organization?
2 How many semi-automatic Injera making machine are needed per annual?
3 How to get semi-automatic Injera making machine?
4 Simple for cleaning?
5 Manual control (is it a limitation)?
6 Have fixed on the automatic injera making machine or portable?
Part II: questionary conduct by written
Instruction; you are sincerely requested to fill the below Likert scale type questions by circling the choice
found in front of each question.
For semiautomatic Injera making machine
1. Prefer choice
A. Rolled B. Flat
2. If rolled, should it be
A. Single B. two pcs c. 4 pcs
3. If flat, should it be
A. Folded B. flat
4. Preferred shape
A. Traditional / circular
B. Rectangular
5. Packing
A. Single
B. Double

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C. Half dozen
6. For multiple packaging
A. Transparent plastic (flexible)
B. Hard plastic with transparent window
C. Opaque hard package (card board) /carton
7. Size preference
A. Small (40 cm) B. Medium (50 cm) C. Large (60 cm)
8. Colour preference
A. White B. Red C. Black
9. Contain
A. Pure teff
B. With rice
C. Wit barley
10. Test preference
A. Lightly sour
B. Sour
C. Nor sour
11. Thickness
A. Very thin (1mm)
B. Thin (2mm)
C. Thick (4mm)
12. Do you prefer to buy from?
A. Supermarket
B. Suq
13. Do you prefer to buy Injera backed?
A. One day ago
B. Two days ago
C. Three days ago
14. Buying location preference if you are buying from supermarket or suq it is because
A. Freshness
B. Price
C. Quality
D. Trustable
15. Demand of dirkosh do you prefers to
A. Make your own

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B. Buy packed.
Part III: questionary conduct by interview
1.
Table 1:customer need identification1
Table 2:Customer need identification 2
Name: ___________________ Occupation:
Address: _______________ Telephone No:
Customer need identification guidelines Response
1. What problem do you observe the current semi-
automatic Injera baking machine?
 Difficult to use specially for those
whose mass production/high
production mix
 High energy consumption
 Limited function, one function
(only for baking)
 Not automated
2. What kind of improvement do you recommend on
current semi-automatic Injera making machine?
 it can rotate
 Cost wise
 Easy to use
 occupies small space
 maintainability
 reliability
 durability
 easy to manufacture
Name: __________________ Occupation:
Address: _________________ Phone No:
Customer need identification guidelines Responses
1. What problem do you face current semi-
automatic Injera making machine?
 Similar height for long and short person
 Used only for baking
 Not automated
 Energy consumption is high
2. What kind of improvement do you suggest on
current semi-automatic Injera making
machine?
 move up and down and it can rotate
 Safe to use
 Simplify the operation
 Easy to maintenance

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Table 3:Customer need identification 3
Name: _________________ occupation: ______________________
Address: ________________________ Phone No: ______________
No. Customer need identification guidelines Response
1. What kind of feature do you want the semi-
automatic Injera making machine to
provide?
 I need less energy consumption of
baking machine
 I want to automated baking machine
 I Need high quality of baking
machine
 I need strong product customization
of baking machine
 I need low time-to-market
2. What do you like about current/existing
semi-automatic Injera making machine?
 I like it to be use less weight
 I like it to be manufactured in
different shape and size for
advantage of ….
 I like it easy to maintain
3. What problem do you face about current
semi-automatic Injera making machine?  Not comfortable respect to???
 low time-to-market
 prices
4. What kind of improvement do you want on
current/existing semi-automatic Injera
making machine?
 high product modularity
 flexible Automation/ automated
 integrated production systems and
new technologies
 can rotate
 can easy and safe to use/ will be
comfortable
 flexible manufacturing systems
 product development techniques

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Interview
In the interview we considered occupation, and variety of users and the responses are the most
frequently answered by different interviewees.
This interview was held by going at our customers working places. For each type of customer, we
prepared questioners that fit to his/her working condition. We interviewed our customer one to one so
that they can express their ideas freely as a result we can get reliable information.
Table 4: Customer need identification from operator
Name: ________________ occupation: machine operator
Address: marcato
No. Customer need identification guide line Response
1 What machine do you usually
manufacture?
Crasher
Thresher
Biogas electrical mitad
Semi-automated Injera baking machine
2 Do you think can you manufacture a
semi-automated Injera making machine?
Yes, possible
3 What kind of manufacturing process do
you follow?
Sketch
Layout and bench work
Sheet metal work
Drilling
Turning
Milling
Welding
Soldering
Grinding
Assembly
Coating
4 What kind of machine tool do you use? Sheet metal folding and cutting machine
Lathe machine
Milling machine
Shaper machine
Grinding machine
Soldering gun
Welding machine
Power hacksaw
Compressor for paint
5 What kinds of material do you use? Tubular aluminium
Alloy steel
Advanced material, plastic, composite
Aluminum sheet
Electric wire

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2.2. Identification Of Customer Need
Identifying the customer need is the most important task in developing a new product. Identification
of customer need for semiautomatic injera making machine follows the following steps:
1. gather raw data from the customer
2. Interpret raw data in terms of customer need
3. Organize the need into hierarchy
4. Establish the relative importance of the need
5. Reflect on the result and the process
2.2.1. Gather raw data from the customer
I have gathered the raw data through direct observation of the existing product and through randomly
carried out interviews with the users of the existing product i.e., Injera rolling machine for an
Automatic Injera Baking Machine at different locations. Moreover, in the interviewee selection we
considered occupation and social status variations aiming to get a wider and relevant information
that can be useful in the subsequent processes.
In this stage a lots of customer needs were identified through the following ways:
2.2.1.1. Interview
The designer discusses with 30 to 40 customers about the product in the customer environment in one-
to-one basis.
2.2.1.2. Focus group
In the focus group session, a group of 10 customers discuss about the product and revealed a lot of
important information including the strength and weakness of the existing machine.
2.2.1.3. Observation
Observing customers in their use environment while using the product. During observation the designer
observes some customers using the product to bake foods other than injera like bread.
2.2.2. Interpreted customer need
Primary needs:
Automation
Ergonomic design
Low energy usage
Easy to maintain
Secondary needs
Cost effective
Compacted
Flexible use
It has less weight

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Question/prompt Customer statement Interpreted
need
Typical uses I used to bake different foods other than injera
like bread
Flexible use
Likes I like user friendly height of conventional mitad Ergonomic
design
Cost effective Cost effective
It has small size Compacted
it can be repaired locally Easy to maintain
Dislikes Fatigue automation
I spent a lot in electric bill Low energy
usage
Suggestion improvements Would be better if it weighs less It has less weight
Table 5:Customer data template filled in with sample customer statements & interpreted need.
1) Identification of need:
a) Needs the development of this product missed
The normal trend that Injera is sold is folded. And this creates crease, if it is stored for 2 or 3 days the
injera will lose its moisture and this will make the injera tear at the creases. And instead of a circular
injera we will have several triangular ones.
Plus, now adays people are focusing on making an automatic machine that produce injera, that is without
the needs of people. In the last few years a few designs were patented and lots of designs were popping
everywhere. But all of them needed a human labor at the packing stage.
This proposal will solve this problem. It will be implemented at the end of the baking machine and will
roll and dice it into packable sizes. Even a packing machine can be continued next to the roller, this will
make it fully automatic without need of labor.

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b) Why weren’t these needs met?
This is simply because all of the injera, that are on the market even at the export level, are baked
manually. And in order to implement this system an automatic machine is needed to feed it, which are
currently drawing the attention of a lot of firms and individuals.
c) Did the developers deliberately ignore these needs?
To put it simply NO.
This has not been done because all of the developers (Designers) are focused on solving how to bake it
first, because even the baking machine hasn’t been developed yet.
My intention is to be ready before the developers have come up with their design in order to merge my
design with their product. Which, in my opinion, will complete their product (Machine).

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Chapter 3
Product Specifications
Introduction
Product specification means the precise description of what the product has to do and refer to design
variable of the product. It can provide little specific guidance about how to design and engineer the
product and leave too much margin for subjective interpretation. Product specification expresses
measurable detail about the product with satisfying customer need.
I had spent a great deal of time identifying customer needs. In addition, the members of the team had
interviewed lead users and manufacture of semi-automated Injera baking machine, and also had spent
time working with dealers in their stores. As a result of this process, they had assembled a list of
customer needs.
There is specification that states the product in measurable and subjective way. The following four steps
are considered to establish the product specification.
1. Need Statement
2. Prepare the list of metrics
3. Collect competitive benchmarking information.
4. Set ideal and marginally acceptable target values.
3.1. Need Statement
At this stage, the project group meets, translates and deploys every customer need in one or more
technical performance measures or functions performed by the product. For each need, one or more
technical performances are identified. Needs are established starting from the previous chapter built. To
be well defined, each performance measurement should be characterized in the following ways:
- The unit of measure (the metric) must be defined
- The direction of goodness must be defined (more the better, less the better, target is best)
- Avoid excessive details
- For each feature find target value
The establishment of the relative importance on needs is based on the following decision criteria that
are decided by all the team members and assigned to each of the critical need of the customer.
No. Decision criteria Level of importance out of 5
Feature is undesirable 1
Feature is not important 2
Feature would be nice to have 3
Feature is highly desirable 4
Feature is critical 5
Table 6: level of performance

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Based on the above stated scale, the team score the level of importance in association to for the customer
needs.
No. Need Imp.
1.
Sem-Automated
Injera
making
and
rolling
/cutting
machine
is ergonomically good 5
2. is easy to manufacture 4
3. Is Durable (last long) 4
4. Can be Easy to maintenance 5
5. Is easy to use and operate 4
6. Can be Cost effective 3
7. Uses other power source than human power 2
8. Occupies small space/ compacted 3
9. Flexible use/Can be used for many purposes (i.e.,
make Ethiopian injera, spring roll wrapper, lumpia
sheet, pancake skin, egg skin, bread, etc.,)
2
10. Become Safe to use 5
11. Is Semi-automated 3
12. Is Reliable 4
13. low energy usage 5
14. It has less weight 3
Table 7: level of importance in association to for the customer needs.

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3.2. Prepare the list of metrics
The most useful metrics are those that reflect as directly as possible the degree to which the product
satisfies the customer needs. The relationship between needs and metrics is central to the entire concept
of specifications. The working assumption is that a translation from customer needs to a set of precise,
measurable specifications is possible and that meeting specifications will therefore lead to satisfaction
of the associated customer needs.
List of matrixes for Sem- automated injera baking machine.
Table 8:List of matrixes for Sem- automated injera baking machine
Metric
no.
Need no. Metric Imp Unit
1 3,12 Durability 4 Year
2 3,6,8,9,12,13,14 Maximum load capacity 5 Kg/
3 2,4,5,6 Time to manufacture 4 Hr
4 5,10, 11, 12 operational Speed 3 rpm
5 3,9,11,12 Impact strength (impact load) for
circular rotating convers
3 J/m
6 1,8,9,12 Area to use 5 M2
7 8,9,11 Height to move up and down
level, can rotate
2 M
8 8,9,11 Angle to rotate level 2 Revolution, rad
9 10,11 The resistance to electric current 3 Ohm
10 8, 13 Power source 1 Kwh
11 6,7,9,10, 14 Weight of baking machine 4 N
12 6,7, 11, 13, Capacity of baking 2 #/sec
13 3,6,11,12 Thermal insulation 2 w/m2. K
14 2,4,5,6 Time to assemble 4 Hr
Table 9:The needs-metrics matrix

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3.3. Collect competitive benchmarking information.
The information is gathered from internet, so we become list the competitive benchmarks as bellow:
A. WASS Injera mitad
WASS electronic services, patented, USA, has designed and produced non clay based Injera Mitad of
16‖ size named WASS Mitad grill shown in Figure 1 below. The product is in the North American
market.
The WASS Electronics Mitad 16″ Grill is ready for the rigors of your home or restaurant kitchen. Tested
to endure extended cooking times, you’ll find this heavily researched grill perfect for all your home and
restaurant needs. Whether you’re cooking Injera in an Ethiopian Restaurant, Flatbread Chapatis in a
Mexican Restaurant the WASS Electronics Mitad will meet your quality needs, ensuring that your guests
and family will be delighted by the consistency of your cooking.
Figure 1: Wass injera mitad
B. Automatic Mitad for small scale (Wassie Mulugeta’s injera machine)
Wassie Mulugeta, who owns the successful Wass Ethiopian Restaurant in Hamilton, Ontario,
has “been working the last 12 years to make a fundamental development change in the way we
cook in Ethiopia.” In 2007, he invented a mitad for making injera at home the old-fashioned
way, one piece at a time. He didn’t have the money to market it at the time, but his restaurant
was successful, and now his mitad is for sale. His Rotary Baking System and Method for making
injera received a patent in 2011, but so far he hasn’t built one to mass produce injera.
Wassie’s effort to build an injera machine began in 1999 with a conveyor belt system that didn’t
work well, so he put the project aside for a while. He tackled it again in 2006, and again in 2008,
Weight 14 lbs
Dimensions 23 × 18 × 8 in
Power 220v

23. 22 | P a g e
finally creating a machine that worked. But he didn’t have the capital to build it, so he opened
his restaurant instead. He tested his injera machine again in 2010, and he says it now works well.
He just has to find the money to build the factory to go with it.
Figure 2: Automatic mitad for small scale (Wassei Mulugeta injera baking machine)
C. Shega mitad
Figure 3: Shega mitad
D. GELGOOD FULLY AUTOMATIC INJERA MAKING MACHINE
Figure 4: Gel good fully automatic injera baking machine
E. Zelalem semiautomatic Injera baking machine
Designed and manufactured non clay based ZELALEM Injera Machine, by Dr. Wudneh
Admassuan, an Ethiopian-born professor of chemical engineering at university of Idaho. It is

24. 23 | P a g e
Automated Injera Machine for large scale production. The machine produces injera for the
North American market. [https: Ethiopianfood.wordpress.com]
Figure 5: Zelalem semi- automatic injera baking machine
F. The Injerama Machine.
Sisay Shimeles, who has degrees in structural engineering and international finance, where he’s
worked with Pennsylvania State University’s Learning Factory in the School of Engineering to make
an injera machine for use in Ethiopia. After nearly five years of work, and with the help of
California-based designer Michael Ma, Sisay’s first Injerama machine, patented in 2012, arrived
from the manufacturer on July 11. He’s now working to get it to Ethiopia and begin making injera.
But it won’t be just your average injera: Sisay says the bread will be nutritionally fortified to improve
the health of the people who eat it – and who rarely get three meals a day. “This project is
about health, environment and job creation,” Sisay says.
When his first plant is in full operation, Sisay wants to have 10 machines side by side. The process
begins, of course, with the milling of the teff and the mixing and fermenting of the batter: As Sisay
describes it, there’s a milling center, a mixing chamber, a kneading chamber, a re-mixing chamber,
several days of batter fermentation, and then the final re-mixing chamber. Finally, he says, “pumps
take the batter from the final re-mix room directly to the machine ready to spread out to the batter
deposit chamber. You can imagine the number of mixers and fermentation tanks the batter has to
pass through before it reaches the processing machine.”
Figure 6; the Injerama machine

25. 24 | P a g e
G. Conventional mitad (Traditional injera baking machine)
i. ii.
Figure 7: Conventional (Traditional) electric mitad
Figure 8: conventional (Mirt mitad (lakech)
i. In urban areas people do not use wood, but electricity. The injera is also baked on clay with a
cover, but no wood is used. An electric wire runs through the clay. Because of the electric resistance
heat is generated. This spirally shaped wire will also heat the clay equally. The baking method is the
same as the traditional method. The surface of both an electrical and traditional platter is slightly
rounded.
- It does not use wood,
- It can bake in the traditional way,
- It does not produce any smoke,
- It uses electricity which is also very expensive,
- A lot of rural people do not have access to the electricity network, and
- Buying one of these is too expensive for rural people.
ii. “Mirt” is an enclosed Injera stove designed by the former Ethiopian Energy studies and Research
center of the Ministry of Mines and Energy. The name “Mirt” means best. The basic design of “Mirt”
is adopted from those of the Ambo and Burayu enclosed Injera stoves by optimizing to handle different
types of fuels. The stove has six parts. Four arcs which fit together to form the circular combustion
chamber & Two-U-shapes that form circular pot rest. The four arcs of the combustion champers enable
the stoves to avoid cracks due to thermal stresses & also help to handle & transport the stove easily. The
U-shape part is used for pot rest & chimney purposes. The raw materials used for construction of the
“Mirt” stove are cement and pumice. In the areas where pumice is not available, scoria (red ash) or river
sand can be used alternatively. Pumice binds well with cement and is a good insulator. Two grain sizes
of pumice are used. The fine size: 3 mm and coarse grain: 5mm. These two-grain sizes will be mixed in
3 parts fine & 1-part coarse grains. Four parts of these pumice grains will again be mixed with cement
and water. When compared to the three stones stove, Mirt stove has many advantages such as: it is more
efficient than three stones stove and hence reduces fuel consumption which again decreases the rate of
deforestation and desertification; it is less smoky, thus vulnerability of cooks to different respiratory,

26. 25 | P a g e
eye diseases decrease; it is much comfortable than three stones stove during cooking; it reduces fuel
expenditure costs of the household.
The relationship of the new product to competitive products is paramount in determining commercial
success. While the team will have entered the product development process with some idea of how it
wishes to compete in the marketplace, the target specifications are the language the team uses to discuss
and agree on the detailed positioning of its product relative to existing products, both its own and
competitors’. Information on competing products must be gathered to support these positioning
decisions.

27. 26 | P a g e
Need
Metric
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Durability
Maximum
load
capacity
Time
to
manufacture
Operational
Speed
Impact
strength
(impact
load)
for
circular
rotating
conveyer
Area
to
use
Height
to
move
up
and
down
level,
rotate
Angle
to
rotate
seat
level
The
resistance
to
current
Power
source
(dc,
ac
motor
&
electric
or
biogas
Weight
of
baking
machine
Capacity
of
baking
Thermal
insulation
Time
to
assemble
1 Is ergonomically good 
2 Is easy to manufacture  
3 Is durable (last long)    
4 Can be easy to maintenance  
5 Is easy to use and operate   
6 Can be cost effective      
7 Uses other power source   
8 Occupies small space    
9 Can be used for many purposes
(i.e., make Ethiopian injera, spring
roll wrapper, lumpia sheet,
pancake skin, egg skin, bread, etc)
  

 
10 Become Safe to use/ Is
Comfortable
   
11 Is Semi-automated     
12 Is Reliable     
13 Low energy usage    
14 It has less weight  

28. 27 | P a g e
Me
tric
no.
Need no. Metric Im
p.
Unit Automatic
mitad for small
scale (Wassie
Mulugeta’s
injera machine)
Was injera
mitad
Conventio
nal Injera
Mitad
1 3,14 Durability 5 Year 4 5 3.5
2 1,10, 16 Maximum load capacity 5 Kgf 136.1 6.35 136.1
3 2,5,6,7 Time to manufacture 4 Hr 48 22-27 56
4 6,11, 12,
15, 17
operational Speed 3 m/s - - -
5 3,14 Impact strength 3 J/m 345 325 360
6 1,4,9,10,
13
Area to use/ Occupies
space
5 m2 25-30 1.88 34-38
7 4 Height to move up and
down level, can rotate
2 M 0.7-1 0.78 1

29. 28 | P a g e
8 4 Angle to rotate level 2 Revolu
tion,
rad
- - -
9 11 The resistance to
electrical current
3 Ohm ∞ ∞ ∞
10 8, 15 Power source 1 Kwh 220V 220V 220V
11 6,7,9,10,
16
Weight of baking
machine
4 Kg 11.7 6.35 15.9
12 4 Size of mitad 5 In 16 16 40
13 2,3,7,8 Cost 0f Machine 4 $ 1199.5 99-225 2680
14 2,5,9,15 Number of per
revolution
pcs/Rev 12 1 30
15 2,5,9,15 Times to made per
revolution
min/rev 12 1 30
16 2,5,6,7 Time to assemble 4 Hr 2 6 8
Table 10; competition of bench mark
3.4. Ideal and marginally acceptable target values.
In this step, I try to synthesize the available information in order to actually set the target values for
the metrics. I hope that the product will meet some of the idea targets but is confident that a product
can be commercially viable even if it exhibits one or more marginally acceptable characteristics.
Note that these specifications are preliminary because until a product concept is chosen and some of
the designs are worked out, many of the extra trade-offs are uncertain.
Met
ric
no.
Need no. Metric Im
p.
Unit Marginal
value
Accepted
value
1 3,14 Durability 5 Year 5 5
2 1,10, 16 Maximum load capacity 4 Kgf 30 24
3 2,5,6,7 Time to manufacture 3 Hr 64 64
4 6,11, 12, 15,
17
operational Speed 3 m/s
5 3,14 Impact strength 5 J/m
6 1,4,9,10,13 Area to use/ Occupies
space
2 M2 9 9
7 4 Height to move up and
down level, can rotate
2 Revoluti
on, rad
1rev N*rev
8 4 Angle to rotate level 3 Ohm -
9 11 The resistance to electrical
current
1 Kwh - -

30. 29 | P a g e
10 8, 15 Power source 4 W
11 6,7,9,10, 16 Weight of baking machine 5 Kg
12 4 Size of mitad 4 In 16 16
13 2,3,7,8 Cost 0f Machine 3 $ 2680 2680
14 2,5,9,15 Number of per revolution 2 Pcs/rev 30 30
15 2,5,9,15 Product to made per
revolution
2 min/rev 10 10
3 2,5,6,7 Time to assemble 3 Hr 8 8
Table 11: Ideal and marginally acceptable target values.
Chapter 4
Concept Generation
A product design concept is an approximate description of the technology, working principle, and
form of the product. It is a concise description of how the product will satisfy the customer needs. A
concept is usually expressed as a sketch or a rough three-dimensional model and is often accompanied
by a brief textual description.
After the design requirements has been establish, the next step in product design and development is
to generate concepts which satisfy customer requirements.
There is a five-step concept generation method. The method is used to break a complex problem in
sub problems. For our concept generation process of semi -automated Injera baking machine I have
followed these steps to come up with more efficient and effective solution for the problems.
Generally,

31. 30 | P a g e
Figure 9: Five step methods of concept generation
4.1. Clarification of the problem
Functional decomposition is only one of several possible ways to divide a problem into simpler sub-
problems. The two approaches are:
i. Decomposition by sequence of user actions: is often useful for product with very simple
technical function involving a lot of user interaction.
ii. Key customer need decomposition.
The main propose of this step is to clarify the problem consists of developing a general understanding
and then breaking the problem down into sub-problem
 Start with customer need analysis and functional specs as input
 It has limit and scope
Energy
Motion
Signal
(Switch on)
We select decomposition by user action to clarify our problem
 Power source
 Dispenser mechanism
 Polisher mechanism
 Remover mechanism
 Rolling mechanism (Roller: with pins, with clipping, Weight with roller, rolling straw with
needle, rolling straw with guide channel)
 Cutting mechanism (Circular blade rolling, Linear blade chopping, Laser, Saw oscillating)
 Type of semi-automated injera baking
Semi-automated Injera
baking, rolling and
cutting

32. 31 | P a g e
 Control mechanism (Solenoid valve, Positive displacement pump, Induction, Resistor)
4.2. Search Externally
External search is intended to finding existing solution to both the overall problem and the sub-
problem identified during the problem clarification step.
The way of gathering information from external source is benchmark related product. It is the study
of existing products functionality similar to that of the product under development.
External search is information gathering process to find the possible existing solution for the sub
problems of the product. The required time and resources can be minimized by using expand and focus
strategy. The existed Information for semi-automatic injera making machine is gathered through the
following ways:
4.2.1. Interview lead users
Household families are the main lead users for semi-automatic injera making machine. And they
describe about the strength and weakness as well as the likely changes to be made in the existing
products.
4.2.2. Patent search
In the patent search, a lot of invention and technics related to the sub problems have been found.
Publication number US 7,063,008 B2, discuss about using air-based spreader to dispense the batter.
Another invention Publication number US 2018/0035676 A1, uses rotating inline nozzles to dispense
batter over the cooking pan.
4.2.3. Related product benchmarking
For benchmarking purpose, automatic pancake, bread and other related or unrelated machines have
been studied in some detail and many important concepts considered.
4.3. Search internally
Internal search is the use of personal and team knowledge and creativity to generate solution concepts.
There are four guidelines that improve both individual and group searching.
 Suspended judgment.
 Generate a lot of ideas.
 Welcome ideas that may seem infeasible.
 Use graphical and physical media.
Internal search involves using of the capacity of a person or the team to generate a lot of alternative
solutions. The organized team use the following method to develop suitable solutions for semi-automatic
injera making machine.

33. 32 | P a g e
4.3.1. Brainstorming
The team attend both individual and group session for generating concepts. First, all team members
generate concepts individually for few days and then gathered to discuss and refine concepts generated
during individual brainstorming session.
4.3.2. Graphical and physical media
All generated concepts displayed on the wall of the roam by using cardboard and projector to help
the team to deeply understand the concepts.
4.4. Exploring systematically
Concept classification tree enables the team to divide possible solution fragments into independent
categories. Concept classification tree for semi-automatic injera making machine is shown in figure 3.
Concept classification tree: - is used divide the entire space of possibility solution into several
distinct classes which will facilitate comparison and pruning.
Biogas
Store Batter
Power source Electrical
Solar
Figure 10: Concept classification tree power of source
Circular blade rolling
Linear blade chopping
Cutting mechanism
Laser
Saw oscillating
Figure 11: Concept classification tree of cutting mechanism
Roller with pins
Roller with clipping
Rolling mechanism weight with roller
Rolling straw with needle
Rolling straw with guide channel
Figure 12: Concept classification tree of rolling mechanism

34. 33 | P a g e
4.5. Concept Decomposition
In order to simplify the problem semi-automatic injera making machine decomposed into sub problems
as shown below.
Figure 13: (a) black box, (b) functional decomposition of semi-automatic injera machine.
Accept
energy
Convert energy
to rotation
Convert energy to
translation
Belt
conveyor
Delivery
motion
Cooling
system
(Fan)
Batter Store battery Delivery
battery
Pick
Injera
Rolling
Injera
Energy
Mechanic
al energy

35. 34 | P a g e
Figure 14:Functional decomposition diagram for the rolling and cutting injera machine
Figure 15: Concept generation of baking machine
Cutting Injera
Pick to
packing
Packing
Pick to
store

36. 35 | P a g e
Chapter 5
Concept Selection
Introduction
Concept selection is the process of evaluating concept that is found in concept generation
with respect to customer needs and other criteria, comparing the relative strength and
weakness of the concepts, and selecting one or more concept s for further investigation,
testing, or development. Concept selection is often performed in two stages as way to manage
the complexity of evaluating dozens of product concept. The two stages are concept scoring
and concept screening. Both stages follow a six-step process. The steps are:
1. Prepare the selection matrix
2. Rate the concepts
3. Rank the concepts
4. Combine and improve the concepts
5. Selection one or more concepts
6. Reflect on the results and the process
Concept screening
Concept screening is a quick, approximate evaluation aimed at producing a few viable alternatives.
During concept screening, rough initial concepts are evaluated relative to a common reference
concept using the screening matrix.
1. Prepare the selection matrix
Matrix is prepared from short list of criteria for their selection process. These criteria are chosen based
on the customer needs the team has identified, as well as on the needs of the enterprise such as low
manufacturing cost or minimum risk of product liability.
2. Rate the concepts
For rating concepts, it is generally advisable to rate every concept on one criterion before moving to
the next criterion. However, with a large number of concepts, it is faster to use the opposite approach,
to rate each concept completely before moving on to the next concept. According to our rating of the
concepts, its looks like the matrix shown in the table below.
3. Rank the concepts
After rating all the concepts, we sum the numbers of “level of imp” multiply with “%of criteria”
scores and enters the sum for each category, then we calculated the net score by summation of
number. After the summation is done, we have rank-order the concepts. According to the results, the
concepts listed at the numbers 1,2,3 &4 gets the first place.

37. 36 | P a g e
4. Combine and improve the concepts
After rating and ranking the concepts, we have verified the results make sense and then we considered
if there are ways to combine and improve certain concepts.
5. Selection one or more concepts
Once we understand each concept and the relative quality, we decided which concepts are to be
selected for further refinement and analysis. Therefore, according to the results we found, we have
selected the concept listed at the number 1.
6. Reflect on the results and the process
This is a system of selecting good alternative among different model solutions for a particular
problem. There are different types of design matrices that are used to make systematic decisions on
choosing best alternatives of given two or more alternative designs. The following method is selected
so that to help reach at the best decision.
I am happy with the results I found by performing the concept screening matrix of evaluating my
concepts. I think that I don’t need further evaluation activity like see the concept scoring technique of
evaluation concepts for our concept selection, because we have already selected our concepts by using
the concept screening method.
Selection Criteria Weights Based on Relative Importance
Ergonomic
s
Reliability
Maintainabilit
y
Easy
to
use
Cost
wise
Easy
to
manufacture
Durability
Light
weight
Easy
to
move
(sped)
Sum
Weighted
value
(%)
Ergonomic 0 0 1 1 1 0 0 5
12.8
Reliability 1 1 1 0 0 0 0 4
10.3
Maintainability 1 0 1 1 1 0 0 5
12.8
Easy to use 0 1 0 0 0 0 1 4
10.3
Cost wise 0 0 0 1 1 2
5.13
Easy to
manufacture
0 1 0 1 0 1 0 4
10.3
Durability 1 0 1 1 0 1 o 4
10.3
Light weight 1 0 1 0 0 1 0 3
7.69
Easy to move
(speed)
0 0 1 0 0 1 0 0 2
5.13

38. 37 | P a g e
TOTAL
33 100
Table 12: Weight for each selection criteria out of 100%
In the previous sections, customer needs are identified and a lot of concepts has been generated to
satisfy those needs. The next step in product design and development is that to the select the promising
concept among the generated concepts and this process is called concept selection process. The concept
scoring for semi-automatic injera making machine is shown in figure 12.
Relative performance Rating
Much worth than reference 1
Worse than reference 2
Same as reference 3
Better than reference 4
Much better than reference 5
Table 13: Performance rating
For injera making machine
Dispenser
A Solenoid valve E
Polisher
B Induction F
Remover
C Resistor G
Positive displacement
pump
D

39. 38 | P a g e
i. Ranking for baking mechanism
Selection criteria Weight
(%)
concepts
A B C D E F G
Dispens
er
Polishe
r
Remove
r
Positive
pump
displacemen
t
solenoi
d
inducti
on
resista
nce
R WR R WR R WR R WR R WR R WR R W
R
Easy to use 20 4 .8 4 .8 4 .8 4 .8 4 .8 4 .8 4 .8
Easy to move 15 3 .45 3 .45 2 .3 2 .3 4 .6 4 .6 4 .6
Low cost 25 3 .75 2 .5 1 .25 1 .25 3 .75 3 .75 4 1
Ergonomic design 2 4 .08 4 .08 4 .08 4 .08 4 .08 4 .08 4 .0
8
compacted 10 3 .3 4 .4 1 .1 3 .3 4 .4 3 .3 3 .3
automatic 20 5 1 4 .8 4 .8 4 .8 4 .8 4 .8 4 .8
Maintainability 8 4 .32 3 .24 2 .16 3 .24 4 .32 3 .24 4 .3
2
Total score 3.7 3.27 2.49 2.77 3.75 3.65 3.9
Rank 3 5 7 6 2 4 1
Continue Yes Yes No No Yes Yes Yes
Table 14: Concept scoring for semi-automatic injera making machine
In order to generate a concept, I have identified the processed involved, which are rolling and
slicing. So, I tried to come up with a mechanism for both processes. I have a brainstorming
session with a friend so that more ideas can be generated. Here are the ideas we came up with:
For rolling and cutting mechanism
Rolling Cutting
Roller with pins A Circular blade rolling F
Roller with clipping B Linear blade chopping G
Weight with roller C Laser H
Rolling straw with needle D Saw oscillating I

40. 39 | P a g e
Rolling straw with guide
channel
E
Criteria for ranking is selected based on hygiene, production efficiency, investment cost and
availability. Based on these factors we came up with six selection criteria which are listed below:
Selection Criteria
Ease of manufacturability
Ease of maintenance
Durability
Cost of Dev.’s & production
Precision (Reliability)
Cleanability
Ease of manufacturability determines the technology availability to produce it and Cost of
development and production will determine the initial investment cost. These two will have a
little weight because the item will not be produced in mass there will be only few productions.
Whereas ease of maintenance, durability and precision will have higher weight because they are
related to operation of the system, which will determine how efficiently will the system function
rather than how it produced.
Cleanability will have the highest ranking because of hygiene and health issues.
Based on these factors a weight percentage is assigned to every criterion as shown below:
Selection Criteria Weight
Ease of manufacturability 5%
Ease of maintenance 25%
Durability 15%
Cost of Dev’t & production 5%
Precision (Reliability) 20%
Cleanability 30%
Table 15: weight of performance

41. 40 | P a g e
ii. Ranking for rolling mechanism
Concepts for rolling
Roller with
pins
Roller with
clips
Weight with
roller
Rolling straw
with needle
Rolling straw
with guide
channel
Selection Criteria
weight
rating Weight
scored
rating Weight
scored
rating Weight
scored
rating Weight
scored
rating Weight
scored
Ease of
manufacturability
5% 2 0.1 3 .15 4 .2 1 .05 4
.2
Ease of
maintenance
25% 2 .5 4 1 4 1 0 0 3
.75
Durability 15% 1 .15 2 .3 4 .6 2 .3 4
.6
Cost of Dev’t &
production
5% 2 .1 3 .15 4 .2 0 0 1
.05
Precision
(Reliability)
20% 4 .8 3 .6 1 .2 4 .8 3
.6
Cleanability 30% 1 .3 2 .6 4 1.2 0 0 3 .9
Total score
1.95 2.8 3.4 1.15 3.1
Ranking
4 3 1 5 2
Continue
No No Yes No Yes
Table 16: Concept scoring for semi-automatic injera making machine/ ranking of rolling mechanism
Based on the above ranking of the concept’s roller with weight and straw with guide
have a closer score. The differences are on the cost of development & production and
precision, with concept E having higher score on precision, it is harder to dismiss it.
Therefore, I have decided to go with prototype for both concepts C and E.

42. 41 | P a g e
iii. Ranking for cutting mechanism
Concepts for cutting
Circular blade
rolling
Linear blade
chopping
Laser Saw
oscillating
Selection
Criteria
weight
Rating Weight
scored
Rating Weight
scored
Rating Weight
scored
rating Weight
scored
Ease of
manufacturability
5% 4 0.2 4 0.2 1 0.05 2
0.1
Ease of
maintenance
25% 2 0.5 3 0.75 4 1 1
0.25
Durability 15% 4 0.6 4 0.6 3 0.45 2 0.3
Cost of Dev’t &
production
5% 4 0.2 4 0.2 2 0.1 3
0.15
Precision
(Reliability)
20% 3 0.6 2 0.4 4 0.8 1
0.2
Cleanability 30% 3 0.9 2 0.6 4 1.2 0 0
Total score
3 2.75 3.6
1
Ranking
2 3 1
4
Continue
No No Yes
No
Table 17: Concept scoring for semi-automatic injera makingmachine/ ranking of cutting mechanism
Based on the above ranking of the concepts cutting with laser has a highest score. Even if it has
higher cost of initial investment, it outweighs the others on precision and cleanability which have
high weight. Therefore, the chosen concept to proceed to prototyping for cutting mechanism will
be concept H laser, if prototype didn’t perform well the runner (concept F circular blade) will be
tested.

43. 42 | P a g e
Table 18: Quality function deployment

44. 43 | P a g e
Chapter 6
Concept Testing
Concept testing is closely related to concept selection in that both activities aim to further narrow the
set of concepts under consideration. However, concept testing is distinct in that it is based on data
gathered directly from potential customer and relies to a lesser degree on judgments made by the
development team. The reason that concept testing generally follows concept selection is that a team
cannot feasibly test more than a few concepts directly with the potential customer. As a result, a team
must first narrow a set of alternatives under consideration to very few.
Concept testing is also closely related to prototyping, because concept testing invariably involves some
kind of representation of the product concept, of a prototype. A team may choose not to do any concept
testing at all if the time required to test the concept is large relative to the product life cycles in the
product category, or if the cost of testing is large relative to the cost of actually launching the product.
There are seven steps for testing product concepts.
1. Define the purpose of the concept test.
2. Choose a survey population.
3. Choose a survey format.
4. Communicate the concept.
5. Measure customer response.
6. Interpret the result.
7. Reflect on the results and the purpose.
Most of the steps for testing concepts of a product design are based on experimental activities, if we
start with the first step which is:
1. Defining the purpose of the concept test: it is essentially an experimental activity, and as with any
experiment, knowing the purpose of the experiment is essential to designing an effective experimental
method. This step is closely analogous to “defining the purpose” in prototyping.
2. Choose a survey population: An assumption underlying the concept test is that the population of
potential customers surveyed reflects that of the target market for the product.
3. Choose a survey format: the following formats are commonly used in concept testing:
i. Face-to-face interaction
ii. Telephone
iii. Postal mail
iv. Electronic mail
v. Internet
Each of these formats presents risks of sample bias. From the above formats “face- to-face interaction”
when presenting multiple concept alternatives or when soliciting ideas for improving a concept.
4. Communicate the concept
5. Measure customer response
6. Interpret the results
7. Reflect the results and the process.

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As I can understand, concept testing is more of experimental or practical activities and also most of the
methodological steps of concept testing require a direct contact with the potential customers, and it needs
a serious survey on the potential customers. I would be pleased if we got the time and the required
resources to conduct the concept testing but I are sorry that we couldn’t conduct it.
Chapter 7
Product Architecture
Introduction
Product architecture is the arrangement of the physical elements of a product to carry out its required
functions. A product’s architecture is selected to establish the best system for functional success once a
design concept has been chosen. It can be thought of in both functional and physical terms. The
functional elements of a product are the individual operations and transformations that contribute to the
overall performance of the product. Functional elements are usually described in schematic form before
they are reduced to specific technologies, components, or physical working principles.
The physical elements of a product are the parts, components, and subassemblies that ultimately
implement the product’s functions. The physical elements become more defined as development
progresses. Some physical elements are dictated by the product concept, and others become defined
during the detail phase. The physical elements of a typically organized into several major physical
building blocks, which we call it chunks. Each chunk is then made up of a collection of components that
implement the functions of the product. The architecture of a product is the scheme by which the
functional elements of the product are arranged into physical chunks and by which the chunks interact.
Establishing the architecture
There is a four-step method to structure the decision process:
1. Create a schematic of the product.
2. Cluster the elements of the schematic.
3. Create a rough geometric layout.
4. Identify the fundamental and incidental interactions.

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Step 1: Creating a schematic of the product
A schematic is a diagram representing the team’s understanding of the constituent elements of the
product. The schematic created will not be unique. The specific choices made in creating the schematic,
such as the choice of functional elements and their arrangement, partly defined the product architecture.
The following schematic representation shows the schematic of semi-automated Injer baking, rolling
and cutting.
Step 2: cluster the elements of the schematic
On this step we’ll assign each of the schematic to a chunk. One possible assignment of elements to
chunks is shown in the exhibit 16 which consisting of 8 chunks. One procedure for managing the
complexity of the alternatives is begin with assumption that each element of the schematic will be
assigned to its own chunk, and then successively cluster elements were advantageous. To determine
when there are advantages to clustering, there are factors which echo the implications.
• Geometric integration and precision
• Function sharing
• Capabilities of vendors
• Similarity of design or production technology
• Localization of change
• Accommodating variety
• Enabling standardization
• Portability of the interfaces
Step 3: Create a rough geometric layout
A geometric layout can be created in two or three dimensions, using drawings, computer models or
physical models (of cardboard or foam, for example). Exhibit 3 shows a geometric layout of the SIBM,
positioning the major chunks described before.
Step 4: Identify the fundamental and incidental interactions
There are two categories of interactions between chunks. First, fundamental interactions are those
corresponding to the lines on the schematic that connect the chunks to one another. Second, incidental
interactions are those that arise because of particular physical implementation of functional elements or
because of the geometric arrangement of the chunks.
While the fundamental interactions are explicitly represented by the schematic showing the clustering
of the elements into chunks, the incidental interactions must be documented in some other way. Exhibit
18 shows a possible incidental interaction graph for the SIBM.

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Fig-3: Concept ca tree
Design concept
1. The first design concept uses a rectangular bar with a constant diameter hole to pour the batter from
the reservoir placed above it, only with a gravitational force, on to the circular clay plate. A servo
motor controlled by an Arduino is used to give the batter a circular shape. Another rectangular bar
facing directly above the holes of the other bar, is used to close them after 180° revolution of the
servo motor. Only 180° revolution is needed because the bar we are using to pour the batter have
holes through its length and the servo motor is placed at the middle of it. One side of the bar pours
half of the injera and the remaining half is poured by the other side giving the batter a circular shape.
After two or three minutes of cooking time the take out starts automatically with a plate going under
the baked injera using a rotational motion and while doing so it opens up the cover by a cylindrical
cam and a roller follower attached to the cover. Then again, the cam and follower close the cover
when the plate reaches its original place. These processes repeat themselves until the batter reservoir
is empty.

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In this design concept the baked injera is collected in the rotating circular collector that have a
constant speed with the conveyor and each receiver is capable of holding up to 30 injera. A spring is
attached to each receiver for balancing mechanism and the collected injera is pushed away automatically
from the collector when the receiver reaches its limit. This is done by a hydraulic piston.
2. This design concept uses a pump to pour the injera batter, which is enough to bake one injera at a time,
from the first reservoir to the second or temporary reservoir through a hose. From the temporary
reservoir the batter is poured on the rotating circular clay plate. A DC motor is used to rotate a hollow
shaft with bearing found at the canter of the cooking system and a beam transferring this motion to the
cooking frame causing the clay plate along with its frame, containing the resistance heating coil, to
rotate. Two levers, where their motion is controlled by a disc cam, one for each, enables the two lever
followers to move back and forth closing and opening the opening that found on the temporary
reservoir. This motion of the two symmetric levers gives the batter a circular shape when reaching the
rotating clay plate. After two or three minutes of baking time through non-rotating cover the baked
injera reaches a conveyor belt, with a cooling system, where it leaves the cooking plate and taken to
the collecting system. After the baked injera is taken out from the clay plate and before reaching the
temporary reservoir the clay part is cleaned by a rotating cleaner having a separate motor attached to
the hollow shaft by a connecting rod. And these processes continue simultaneously.
After the baking process takes place the injera will passes through the conveyor and collected in the
collector which is placed next to the conveyor for packaging system. We have two alternative designs
of collecting mechanism for the system of good packaging and storing.
Main part an7d component of baking machine design manufacturing: -
1. Batter spray part
 Batter pump
 Pump hose
 Temporary reservoir
 Slide bar linkage
 Roller (follower)
 Cam lobe (eccentric)
 Motor
 Return spring
 Frame
2. Mitad (clay) part
 Frame stands with roller
 Heater and heater frame
 Clay and clay frame
 Clay cover
 Hollow shaft
 Clay frame and hollow shaft connector (motion transmitter)
 Bearing

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 Motor
 Gear/belt
3. Cleaner
 Motor
 Frame structure
 Cleaner
4. Vacuum pump
5. Conveyor
 Motor
 Belt conveyor (mesh type)
 Fan
 Bearing
 Shaft
6. Collecting Mechanism
7. Rolling and cutting mechanism
8. Packing mechanism
I have some ideas about 6,7,8 and I’ll talk about it next.
Figure 16: sketch of Injera baking system in design concept
Figure 17: the top view of design concept by auto cad

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Figure 18: 2D semi- automated injera baking machine design by auto cad
This design concept uses a fast return collecting mechanism.
Figure 19:collecting system using fast return mechanism
Figure 20:Solid model of single part of semi-automatic Injera baking machine.

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Design For Manufacturing
To fill the gap between customers and design specifications, the approach of design for “X” is used.
From these approaches, design for manufacturing is one of the most important approaches to be
considered.
It directly addresses cost producing the component parts and economic success of the product. It
needs experience of the designer in sketching the components, ability to find alternative design for a
specific part or sub assembly, a detail knowledge about the production and assembly processes,
estimation of part production and assembly costs.
Design for Manufacturing is the most common
 it directly addresses manufacturing costs.
 economic success of the product DFM utilize
 Sketches, drawings, product specification and design alternative
 a detail understanding of production and assembly processes
 estimation of manufacturing costs, production volumes and ramp-up timing
Design for manufacturing process (DFMP)
We can express DFM process in the following block diagram.
Manufacturing cost is the sum of all of the expenditures for
 the inputs of the system and
 for disposal of the waste produced by the system.
Equipment Information Tooling
Waste
Energy Supplies Services
Manufacturing cost is the sum of all of the expenditures for
 the inputs of the system and
 for disposal of the waste produced by the
Way of categorizing cost of element for manufacturing
Manufacturing System
Purchased components
Labor
Raw
Finished Goods

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Elements of manufacturing cost of product
1. Component costs
2. Assembly costs
3. Overhead costs
Generally, costs can be classified as fixed or variable costs.
Fixed costs- are costs that do not increase or decrease with the number of parts produced.
Variable costs- are costs that increase or decrease with amount of part produced.
There are steps to follow for estimating manufacturing costs. These are;
 Estimate the cost of standard elements
 Estimating the cost of custom products
 Estimating cost of assembly
 Estimate the overhead costs
1. Reduce the cost of components
The cost of components is a major cost in design and needs consideration. To reduce the cost of the
components, we are going to follow the following principles.
 Understand the process constraints and cost drivers.
 Redesign components to eliminate processing steps
 Choose appropriate economic scale for the part process.
 Standardize components and processes.
2. Reduce the cost of assembly
Manufacturing Cost
Components Assembly Overhead
Standard Custom Labour Equipment
and Tooling
Support Indirect
Allocation
Raw
Material
Processing Tooling

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Cost of assembly can be minimized by using integrated parts. That means reducing the number of
parts to be assembled. In doing so, the advantages and disadvantages must be considered, and the
customer preference must also be considered.
Design for assembly index
DFA index= theoretical minimum number of parts*(3 second)
Estimated total assembly time
Reduce the cost of supporting production
In production and during assembling operations, the cost must be reduced as much as possible. To
reduce such kinds of costs, we can take the following measures.
a) Minimize systemic complexity by using smart design decisions.
b) Error proofing-by anticipating possible failure modes, take appropriate corrective measure the
early stages. The other choice is to use a color coding for parts that look like the same.
Economic Analysis
Economic analysis is essential part of product development for a company launching a new product. Bill
of material and breakeven point analysis has been done for semi-automatic injera making machine.
Bill of material
The bill of material comprises assemblies, sub-assemblies, and parts of the product. The bill of material
for semi-automatic injera making machine is shown below in table 4.
Item
no.
Part name Qty Unit cost Total cost
1. Mitad (clay) 1 350 350
2. Cover 1 150 150
3. AFBMA220.1-48.20-18, SI,
NC,1868
2 150 300
4. Shaft 1 100 100
5. Connecting rod 1 100 100
6. Bottle 1 130 130
7. Pan 1 80 80
8. Spring 1 400 400
9. B18,6,7M-M3.5X0.6X16
Indented HFMS--16N
2 150 300
10. DIN EN 28734-5X12-A-st 3 5 15
11. Polishing plate 1 5 5

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12. motor 1 1 1200 120
13. motor 2 1 1600 1600
14. Solenoid valve 1 250 250
15. Thermostat 1 300 300
16. Resistor 1 250 250
Total 4055
Table 19: bill of material
Break-evenpoint analysis
Break-even point is the point at which the total cost (total fixed + total variable cost) equals total revenue
(number of products to be sold* unit price). Break-even point analysis determines the number of
products the company need to sell to cover the cost of doing business.
The fixed cost needed for the start of the manufacturing of semi-automatic injera making machine is
found to be 1 million birrs. From bill of material the unit cost of the machine is 4055 birrs. And revenue
per machine is 4500 birrs. Let, Y= number of products to be sold.
Thus, the break-even point can be calculated by
Total cost = Total revenue
1000000 + 4055*Y = Y*4500, Y=2248 units
Therefore, it is showed that the break-even point of semi-automatic injera making machine is 2248 units.
The graph of breakeven point analysis is shown in figure blow.
Figure 21: Break even analysis for semi-automatic injera baking machine graph

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Conclusion
In this project, the customer need for semi-automatic injera making machine is identified and
interpreted. Concepts generated to satisfy the customer requirement and promising concepts selected
through concept scoring method.
I have tried to discuss about the design and development of adjustable and semi- automated Injer
Baking, rolling and cutting machine. From chapter one through chapter seven I have included all main
procedures and other so many subs procedural steps to get a well designed and developed Injer baking
machine, those are the mission statement; customer need identification; product specification; concept
generation; concept selection and product architecture are the main. From the beginning of the project
to the end the design I tied to follow each step of the generic phase of product development. At first, the
I stated the problem, set objectives and limit the scope of the project. By the end of the project the I
reached the major objectives of the project. The mission statements defined used as a guide line for
development. Although it was difficult to get data from the customer, the I get about 5 types customer
interviews and assess those customer needs. On the basis of the design team knowledge level and
capacity of majority of the customers, the product is designed to reach the basic needs of the customers.
In general, the project was a very supportive incident for developing our knowledge of product design
and development; we found it very helpful for our future work life.

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Acknowledgement
First of all, I thank Dr. Haileleoul Sahle for teaching me important courses and providing the
necessary materials. And also, am grateful to all individuals and friends who participate in data
collection and brainstorming session.

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Reference
[1] Product design and development; Karl T. Ulrich and Steven D. Eppinger; third edition.
[2] Dave Sood, “Injera Electric Baking energy use impacts in Addis Ababa, Ethiopia, A World
Bank-funded Study’’, Consultant, USA, 2010.
[3] Jan Carel et al., “The Development of an Energy Efficient Electric Mitad for Baking Injeras in
Ethiopia’’, 25th Domestic Use of Energy Conference, 2017.
[4] K. T. Ulrich and S. D. Eppinger, “Product Design and Development,” 5th Edition, McGraw-
Hill, New York, 2012.
[5] Melkamu Yayeh “Integration of Scheffler Concentrator and Thermal Storage Device for Indoor
Injera Baking’’, Addis Ababa University, 2013.
[6] Project document on “Electric Injera Mitad Energy Efficiency Standards and Labeling”, Danas
Electrical Engineering, 2015.
[7] Yousef Haik et al. Engineering Design Process, 2nd edition, Global Engineering: Christopher
M. Shortt, US, 2011.