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Project Proposal & Feasibility Study 9 December 2005

Team 3:

Jeff Blech Joshua Cypher Steve Krueger

Joyce Vander Weide Kayt Vincent

Advisor: Professor J. Aubrey Sykes

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Abstract: Team “Got Juice?” will design, test, and build two machines. These machines will improve two

steps of a process currently used in Uganda to process cassava into Gari. The steps in the current process include harvesting, peeling, washing, grinding, pressing, drying, and storing. Got Juice will design one machine to improve the grinding step and one machine to improve the pressing step. The grinding machine will produce cassava particles with a diameter of 0.1 to 2 mm. The second machine will employ a press to squeeze the ground cassava and separate the solids from the liquid. The solid and liquid products will be collected separately and processed further according to the current process. The moisture content of the squeezed cassava will be below 15% (by weight) after the pressing stage is complete. The two machines will be safe, durable, lightweight and human-powered.

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Table of Contents 1. Introduction…………………………………………………………..…..1 2. Scope ………………………………………………………………...…..1

2.1 Objectives 2.2 Project Requirements 2.3 Deliverables

3. Design Considerations………………………………………………..…..2 3.1 Ethical Considerations

3.1.1 Caring 3.1.2 Stewardship 3.1.3 Cultural Appropriateness

3.2 Food Product Considerations 3.3 Physical Considerations

3.3.1 Materials Used 3.3.2 Power Sources 3.3.3 Ease of Use 3.3.4 Reparability

4. Research ……………………………………………………………….…4 4.1 Cassava 4.2 Gari 4.3 Alternative Mechanisms

4.3.1 Grinding 4.3.1.1 Spinning blade 4.3.1.2 Motorized motor and pestle 4.3.1.3 Hammer mill 4.3.1.4 Spinning Cylinder 4.3.1.5 Spinning disk with teeth 4.3.1.6 Grinding Design Matrix

4.3.2 Juice Extraction 4.3.2.1 Large rollers 4.3.2.2 Centrifuge 4.3.2.3 Screw press 4.3.2.4 Vacuum chamber 4.3.2.5 Hydraulic press 4.3.2.6 Juice Extraction Design Matrix

4.3.3 Mechanism to transport cassava between stages 4.3.3.1 Conveyor 4.3.3.2 Air to blow cassava 4.3.3.3 Gravity 4.3.3.4 Burlap Sacks

5. Feasibility Analysis……………………………………………….…….12 5.1 Availability 5.2 Cassava Processing

5.2.1 Grinding Feasibility 5.2.2 Pressing Feasibility 5.2.3 Drying Feasibility

5.3 Quality Assessment 5.4 Funding / Material Gathering

6. Project Management………………………………………………….....15 6.1 Team Organization

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6.2 Document Organization 6.3 Schedule 6.4 Budget 6.5 Website 6.6 Procurement

7. Design…...……………………………………………………….……..17 7.1 Grinder Design 7.2 Juice Extraction Design

8. Conclusions…………………………………………………………….17 9. References……………………………………………………………...19 10. Appendices……………………………………………………………..20

List of Figures Figure 3.1: Taxonomy of Design Considerations………………………………...2 Figure 4.1: Nutritional Facts for cassava and potato……………………………...4 Figure 4.2: The Current Process for making Gari………………………………...5 Figure 4.3: Spinning Blade………………………………………………………..5 Figure 4.4: A Traditional Mortar & Pestle ……………………………………….6 Figure 4.5: The blades of a hammer mill…………………………………………6 Figure 4.6: The Current Cylinder ………………………………………………...7 Figure 4.7: The proposed spinning disk…………………………………………..7 Figure 4.8: Large Rollers………………………………………………………….8 Figure 4.9: Screw Press…………………………………………………………....9 Figure 4.10: A Burlap Sack……………………………………………………...12 Figure 5.1: Growing cassava……………………………………………………..13 Figure 5.2: Juice extraction over time……………………………………………14 Figure 5.3: Gari size……………………………………………………………...15 Figure 7.1: Grinding Device……………………………………………………..17 Figure 7.2: Pressing Device……………………………………………………...17 List of Tables Table 4.1: Design Matrix for Grinding stage……………………………………..8 Table 4.2: Design Matrix for Juice Extraction stage…………………………….11 Table 6.4.4: Budget………………………………………………………………16

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1. Introduction The idea of designing machinery to improve the process of making Gari from cassava was

introduced by the Christian Reformed World Relief Committee (CRWRC). The CRWRC is undertaking the creation of a cassava farm in northern Uganda, which will allow Ugandans to produce large quantities of Gari made from locally grown cassava.

Cassava is a root crop native to Central America, but now widely grown throughout Africa and parts of Southeast Asia. Cassava is a variety of tuber, similar to a potato, in both physical and nutritional characteristics. Unlike a potato, however, cassava has a thick, coarse skin. Cassava is drought resistant and grows well in poor soils; making the crop ideal for both wet and dry climates.

A negative characteristic of cassava is the tendency to spoil rapidly once exposed to air. Spoilage begins within 48 hours of air exposure1. To avoid spoilage, cassava is often processed into Gari, an excellent solution to the spoilage problem because the product can be stored for up to two years if kept dry. The specific characteristics of Gari are discussed in detail in section 4.2. Gari is produced throughout Africa using various processing methods. This project deals with only one of the possible methods of Gari production. The Gari making process "Got Juice?" will improve uses a series of steps that take a total of 2-3 days. First, the cassava is peeled and washed. Next, the cassava is ground to a pulp. This pulp is placed in burlap sacks and placed in a screw press overnight to squeeze out the juice which soaks into the ground and is not collected. After most of the juice has been removed, the pressed cassava is placed on large metal trays and dried over an open fire. The cassava is stirred constantly for about thirty minutes to facilitate even drying. Finally, the product, now called Gari, is removed from the trays and packaged for sale and consumption. The product can be eaten plain, mixed with liquid, or made into flat bread2. 2. Scope 2.1 Objective

Improving the grinding and pressing steps of the Gari making process will be the focus of this project. The main goal is to create functional cassava grinding and pressing machines. The grinder must grind the cassava into very small particles between 0.1 and 2 mm in diameter. The pressing step must save the juice removed from the cassava which can be used to make industrial starch, wood glue, and industrial alcohol.

2.2 Project Requirements

The machine requirements are: • Human-powered with option for motor • Produce cassava particles between 0.1 mm and 2 mm in diameter. • Remove 80% of the moisture from ground cassava • Improve upon the 13.2% cassava loss of the current process3 • Transportable by bicycle • Easy maintenance in rural locations • Durable • Inexpensive • Easy to clean • Defined by drawings so the machine can be manufactured • Protective coverings on all moving parts

1 Taiwo, 90. 2 Ogwok, Jacob. E-mail to the author. 24 Oct. 2005. 3 Taiwo, 90.

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2.3 Deliverables At the end of the first semester an initial prototype will be constructed for both the grinding and

pressing stages. The prototypes will identify significant construction obstacles and any improvements that are required. Along with the prototypes, a feasibility analysis will be completed on the project which is included in this document.

At the end of the second semester, a functional model will be completed and tested. The machines will be sent to Uganda along with manufacturing plans. The plans will allow Ugandans to build the machines locally. 3. Design Considerations

There are many different facets that must be considered in the design process, as shown in Figure 3.1.

3.1 Ethical Considerations

Design norms are helpful guidelines that assist in design selection. For this project, cultural appropriateness, caring, and stewardship were chosen as the most important design norms. 3.1.1 Caring

The design norm of caring applies to designing a machine to produce cassava for several reasons. First of all, food is a necessity of life, yet there are many places around the world that lack this resource. Designing a machine that increases the production of a staple food for less cost demonstrates caring for the people who will benefit from the product.

Additionally, there are many safety concerns with the current cassava production process. As a method of caring for the men and women operating the machines, safety will be taken into consideration when choosing a final design.

3.1.2 Stewardship

Stewardship is another applicable design norm. This project provides an excellent opportunity to use a few resources to produce a vital product for many people. Creating a machine that facilitates the production of food is creating a way for many people to act in fulfillment of the mandate given in Proverbs 3:27, “Do not withhold good from those who deserve it, when it is in your power to act” (NIV).

3.1.3 Cultural Appropriateness

Cultural appropriateness also applies to the design of a food processing machine for third world countries. Because the societal structure in most parts of rural Africa differs significantly from American structure the design must consider several key differences. The most important difference is the machine operator. Based on the experience and observations of team members and others who have spent time in developing countries, women are likely to be the primary operators of these machines, therefore, female

Figure 3.1: Taxonomy of Design Considerations

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preferences must be a considerations in the design. Similarly, the tendencies not to repair broken machines, and for unattached parts to be stolen must be take into consideration. Additionally, the design must be simple enough to manufacture in Uganda which means that both machines must use resources available in eastern Africa in construction.

3.2 Food Product Considerations

The quality and quantity of Gari produced are also important considerations for the process. To meet the demands of the people, the chosen design will increase the current production rate of Gari. Currently the process can take 12 hours or more to complete the grinding and pressing stage. Additionally, Gari has a specific size for the individual grains. Changing the grinding mechanism should not affect this size, referred to as the quality. This is discussed more in the feasibility section of this report.

3.3 Physical Considerations An additional set of design considerations are the materials used, the power sources, ease of use, and reparability. 3.3.1 Materials Used

Among the physical considerations for the design is choosing the materials from which the machine will be constructed. The most important material consideration is the availability of the materials in Uganda. The machine will be designed so that most of the parts can be manufactured in Uganda, thus using materials that are readily available in that environment is an important consideration.

The durability of the machine is another important physical design consideration. The operating environment has the potential to be harsh, with extreme heat and humidity. These conditions necessitate choosing materials that are corrosion resistant. Additionally, the machine will be used for many years by many different operators, so the materials of machine must withstand prolonged heavy use.

The weight of the final product is another design consideration directly influenced by the chosen materials. Due to the potential need to transport the machine between locations, the machine should be designed to be broken down into light weight, easily transportable components.

3.3.2 Power Sources

Another consideration for the design is the power sources readily available in eastern Africa. Because the cost of fuel is increasing dramatically, the importance of not depending on an expendable resource is evident. The possibility that this machine might be used in locations that do not have easy access to a hydrocarbon fuel is also significant. For this reason the machine should have the option of being powered by a renewable source, such as human-power.

3.3.3 Ease of Use

Ease of use is another essential physical consideration. The machines must be designed to be used easily by various types of operators. Also, the machines should be designed to make the new process similar to the current process. 3.3.4 Reparability

The reparability of the final machine is also significant considerations in the design process. This issue is closely linked with the cultural appropriateness consideration addressed in the ethics section. To counter the cultural tendency to not repair machines, a physical design consideration is creating a machine that is easy to repair locally.

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4. Research During the design process, a number of areas have been researched. Three areas of research are highlighted in this section, cassava, Gari, and alternative design solutions. 4.1 Cassava Cassava is a tuber similar to a potato in texture and nutritional value. One key difference is that cassava has a thick, course skin. Cassava has a moisture ratio in excess of 60 %wt.4 Cassava's principle disadvantage is that cassava is extremely perishable. Cassava will begin to deteriorate in 24-48 hours once exposed to air5. Fortunately, cassava can be left in the ground prior to harvesting for up to 2 years. This allows cassava to be harvested in small amounts according to the amount that can be processed each day. Nutritionally cassava is frequently compared to a potato. The two tubers have similar physical characteristics, with potatoes having a water content of approximately 80%, and similar nutritional characteristics, as shown in Figure 4.1. Similar foods can be made from potatoes and cassavas as well including cassava chips and fries.4 Neither of these has become popular in North America; however they are eaten in many places around the world. Cassava can also be boiled, fried, or ground into flour.

Nutrition Facts for Potato7 serving size 1 potato (138g)

Amount Per Serving

Calories 128 Calories from Fat

2 % Daily Value*Total Fat 0g 0%Sodium 14mg 1%Total Carbs 29g 10% Fiber 3g 12%Protein 3g Vitamin A 0%Vitamin C 22%Calcium 2%Iron 8%

* Percent Daily Value based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.

Figure 4.1: Nutritional Facts for cassava and potato 4.2 Gari Gari is cassava that has been ground and then dried until the moisture ratio is below 14% (by weight).8 The full process of producing Gari from harvested cassava includes steps of peeling, washing, grinding, pressing, and drying, as shown in Figure 4.2.

4 Oje, 53. 5 Taiwo, 90. 6 Yuca Root by Melissa's. Advertisement. 2005. 7 Nutrition Data. 8 Taiwo, 90.

Nutrition Facts for Cassava6 serving size 2/3 cup (85g)

Amount Per Serving

Calories 120 Calories from Fat

4 % Daily Value*Total Fat 0g 0%Sodium 10mg 0%Total Carbs 27g 9% Fiber 2g 10%Protein 13g Vitamin A 0%Vitamin C 80%Calcium 8%Iron 20%

* Percent Daily Value based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.

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After processing, Gari will stay good for up to 2 years, if stored in a dry, protected place. 9

Currently, the processed Gari is placed in cloth bags and stored in a dry hut until shipping or use. Traditionally there are many ways to eat Gari. Frequently the pieces are eaten plain and dry. They

can also be mixed with a liquid, generally milk or water. Because of the slightly bitter taste, Gari is often mixed with a sweetener, usually sugar, which can be eaten like oatmeal, either warm or cold. If the consistency of the mixture is dough-like, the dough can be formed into cakes and baked or fried.

The juice removed from the cassava during the pressing stage also has uses. These applications include mixing the liquid with animal feed to provide a higher starch diet for the animals. As a result of the high starch content, the juice extracted from cassava can be used to make many industrial products including acetone, alcohol and wood glue.10

4.3 Alternative Mechanisms

“Got Juice” will focus on two steps of the Gari making process outlined in Figure 4.2: grinding, juice extraction, with attention also given to the transport mechanism between the two steps. 4.3.1 Grinding

In the first step, peeled and washed cassava is ground into small particles, roughly the size of corn meal. Five alternative solutions have been identified for this process including a spinning blade, a motorized mortar and pestle, a hammer mill, spinning cylinder and a spinning disk.

4.3.1.1 Spinning Blade

The cassava could be chopped using a spinning blade, similar to the one shown in Figure 4.3. This is the concept used in many domestic food processors, where the food is thrown around in the container by the blade until the final product is well chopped. Some of the advantages and disadvantages for this mechanism are listed below.

Using a standard spinning blade food processor, some experiments were completed and revealed that maintaining a constant partial size was very

9 Taiwo, 90. 10 Okigbo.

Washing Peeling Harvest

Grinding Juice Extraction Drying/Roasting

Figure 4.3: Spinning Blade

Figure 4.2: The Current Process for making Gari

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difficult. Additionally, there are numerous safety concerns with a spinning blade. These two factors eliminated the spinning blade as a usable option.

Advantages Disadvantages

• Proven effective in food processing • Can handle large feed rates

• Safety concerns with a large spinning blade

• Can vary Gari size easily • Efficient

• Possible loss of cassava during processing

• Must replace or sharpen blades when broken or dull

4.3.1.2 Motorized Mortar and Pestle

Alternatively, the cassava could be mashed using a mortar and pestle, similar to the one showed in Figure 4.4. The concept of a mortar and pestle has been used in many food applications around the world. Common large scale applications include grinding corn and other grains. The device is more commonly used on a small scale, having traditionally been used by apothecaries during the Renaissance to grind herbs.11 The proposed device would use a motorized linkage, similar to a robotic arm, to crush the cassava. The mortar and pestle was not pursued due to the amount of time and force required to grind the cassava to a suitable consistency for making Gari. Previous experience grinding potato with a mortar and pestle show the process to be very slow and the ground potato was too coarse. Other advantages and disadvantages are listed below.

Advantages Disadvantages • Has been used by hand to mash cassava

into Gari • Complicated design of motorized

mechanism • Can grind cassava at various angles to

produce Gari with desired size • Quantity restrictions • Speed restrictions

• Might be able to combine with pressing process

• Unknown force to properly mash cassava

• Can reduce lost Gari during processing 4.3.1.3 Hammer mill

Another option considered to grind the cassava was a hammer mill, similar to the one showed in Figure 4.5. The hammer mill uses a screen and spinning cylinder that has blades. The blades would grind the cassava until the pieces are small enough to fit through the screen.

Research into the hammer mill showed that the machine is heavy and requires a large amount of power to operate. In addition to these difficulties, a hammer mill involves many blades that swing around a shaft, each one similar to the spinning blade discussed previously. Using this device would be costly to manufacture and difficult to use safely. Other advantages and disadvantages are shown

11 GourmetSleuth.

Figure 4.4: A Traditional Mortar & Pestle

Figure 4.5: The blades of a hammer mill

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below.

Advantages Disadvantages • Prove effective in food processing • Not easy to transport • Can vary size of Gari easily • Cleaning screen might be difficult • Can be design to handle large loads • Efficient

4.3.1.4 Spinning Cylinders

A different option for the grinding process is to use one or two spinning cylinders with teeth to grind the cassava (see Figure 4.6). The teeth would be small enough and spaced evenly to cut the cassava into the desired size. This is the process currently be used in Uganda.

The cylinder can be replaced as necessary, though such an operation tends to be extensive due to the complicated nature of the part. A list of advantages and disadvantages of the spinning cylinder follows:

Advantages Disadvantages • Currently used in existing Gari producing

machine • More mass than spinning blade (more

upfront cost / more energy to run) • Proven effective in grinding large

quantities of wood • Might be more powerful than necessary • Difficult to manufacture cylinder

• Long lasting • Simple design


• Might have potential to press while grinding

4.3.1.5 Spinning Disk with Teeth

The cassava could also be ground using a disk with teeth, similar to the spinning cylinder that is currently in use. This disk would have teeth on the flat surface and would rotate so that the teeth grind the

cassava, as shown in Figure 4.7. These teeth would be small enough to cut the cassava into the desired size on the flat surface, and would be positioned to allow the cassava to spin off the disk once the piece was ground to the appropriate size.

To test if the proposed spinning disk was a valid option, two simple experiments were completed. The first experiment, using a household juicer, tested the concept of a spinning disk. This experiment produced ground cassava that was much finer than the minimum standard. The small size resulted from the small teeth on the disk of the machine used. For details of this experiment see Appendix A. To test the hypothesis that tooth size controls the size of the cassava

pieces, a second experiment was then done using coarse wood files. The fact that the size of the teeth will control the final size of the Gari was proven using different file sizes. The results of this experiment are shown in Appendix B. Through these two experiments, the spinning disk with teeth was chosen as the final design. The advantages and disadvantages of this system are listed below.

Figure 4.6: The Current Cylinder

Figure 4.7: The proposed spinning disk

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Advantages Disadvantages • Simple design • Long lasting


• The disk will spin the cassava to the sides of the disk, making room for more cassava to be ground

• Difficult to manufacture disk

4.3.1.6 Grinding Design Matrix

To make a decision on which grinding mechanism would be best suited to our application a design matrix,12 shown in Table 4.1, was created. Table 4.1: Design Matrix for Grinding stage

Weighting Spinning

Blade Cylinder Hammer

Mill Spinning

Disk Quality of GARI 9 4 7 9 7 Durability 8 6 8 9 4 Cost 7 8 5 2 7 Safety 6 3 7 5 7 Size/Weight 6 8 6 5 8 Quantity of GARI 5 8 7 8 6 Amount of Power Required 5 8 6 4 7 Ease of Assembly 4 8 7 4 8 Ease of Maintenance 3 8 7 7 8 Weighted Total 342 354 324 355

The spinning cylinder and the spinning disk received almost identical scores after the weighting process. Because the disk scored slightly higher this design was researched more in-depth and chosen for the design. 4.3.2 Juice Extraction:

Juice extraction is the next operation that will be performed on the cassava. In this stage, the goal is to remove the majority of the moisture in a short time. The amount of juice that remains after the pressing operation directly impacts the drying stage. Common practice is to remove approximately 80% of the moisture from the cassava in the pressing stage. Five possible solutions were identified for this stage: large rollers, a centrifuge, a screw press, vacuum chamber, or a hydraulic press. 4.3.2.1 Large Rollers

The first option in the juice extraction process is to use large rollers to press out the juice, similar to the one seen in Figure 4.8. Rollers would be stationary, and cassava would be placed on a conveyor and forced between them. The rollers would be very close together and apply a large load on the cassava. The surface could be slanted, causing the juice to flow away from the cassava. Another alternative would be to create a flat surface with small holes to remove the juice. This would allow the juice to drain out when weight was applied.

12 In the decision matrix, four alternative solutions were ranked in nine categories. A weighting was assigned to each category depending on its importance. To find the best solution, the ranking for each category was multiplied by its weight. These products were summed to find the weighted total for each solution.

Figure 4.8: Large Rollers

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A discussion with former food processing engineers from Hillcrest Christian Reformed Church revealed that large rollers require a significant amount of power to press the cassava while pulling the pieces through the rollers. This force would be larger than what could be produced by human-power and therefore did not meet the standards identified earlier. For this reason, large rollers were not chosen as the final design for the pressing stage. Additional advantages and disadvantages of this system are listed below.


• Weight of roller can be controlled • Would have to spread cassava evenly • Constant force applied as rolled • Bulky (would need a lot of space) • Control speed easily • Large force would speed up wear • Force distributed evenly • Continuous process

• Difficult to apply a very large external force

• Not very consistent result 4.3.2.2 Centrifuge

Another alternative for the pressing stage is to develop a centrifuge that would spin the ground cassava rapidly to separate the juice from the cassava. The sides of the cylinder would be designed to allow moisture to leave while keeping ground cassava inside. The centrifuge would be run until the ground cassava achieved moisture content below a desired level.

After doing several experiments with centrifuges as outlined in Appendix C, the necessary force to remove an adequate amount of moisture was found to be unachievable using human-generated power of about 400 rpm. For this reason, a centrifuge was not chosen as a valid option for pressing cassava. Additional advantages and disadvantages of this system are listed below.


• Fast • Easy to use

• Might not generate enough force to remove the desired amount of juice

• Manual power source possible • Small

• Would be a completely separate operation

• May only handle a small amount of cassava at a time

• Batch process 4.3.2.3 Screw Press

Pressing the cassava with a screw press, similar to the existing system, would be another option to remove the juice from the cassava similar to the one in Figure 4.9. This process would place ground cassava into burlap sacks, and then place the sacks into the press. The press would then be used to squeeze out the juice which would be collected.

The current process requires that the cassava be left in the screw press over night to remove the necessary amount of moisture. Since speed is a large part of the scope of the project, this idea was not chosen as a final design. Additional advantages and disadvantages of this system are listed below.

Figure 4.9: A Screw Press

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• Consistent, known to work • No external power source needed

• Some of the juice would be lost to evaporation

• Cheap, simple • Slow (process bottleneck) • Limited setup and can be left alone for the

pressing time • Would not be automated • Batch process

4.3.2.4 Vacuum Chamber

Alternatively, a vacuum chamber could be used to suck the juice out. This would be the opposite of the centrifuge, using pressure to pull, rather than push, the juice out. As with the centrifuge, the sides of the chamber would be designed to allow moisture to pass through, but separate the ground cassava .

To make this process work, a large air compressor would have to be incorporated into the design which would complicate the design. This would contradict the scope as well as make the project much more expensive. For these reason, the vacuum chamber was determined to be not a valid option for this project. Additional advantages and disadvantages of this system are listed below.


• Fast • Expensive • Uniform results • External power source • Easy collection of juice • Would need a lot of suction • Might require a large machine to get the

necessary suction • Difficult to maintain/repair in Africa • Complex machinery

4.3.2.5 Hydraulic Press

A final possibility for the juice extraction process is to use a hydraulic press. Ground cassava would be loaded into sacks and placed on the press. The hydraulic press can apply a large force to a small area, thus decreasing the time required to extract the juice. Juice collection would occur while being removed from the cassava.

Hydraulics are reliable and widely available. This wide availability leads to the systems being inexpensive. Hydraulic cylinders are capable of producing a large force supported use of some form of hydraulic in the pressing stage. These advantages were verified in an experiment where ground cassava was pressed with a hydraulic press (see Appendix D for more information). Consequently, a hydraulic press design was chosen for the pressing stage. Additional advantages and disadvantages of this system are listed below.


• Will extract juice faster than current method

• External power source needed • Large force requires a strong structure

• Can be left alone while extracting juice • Batch process • Durable • Smaller and easier to transport

4.3.2.6 Juice Extraction Design Matrix

The decision matrix used to help choose the best solution for the pressing stage is as shown in Table 4.2.

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Table 4.2: Design Matrix for Juice Extraction stage

WeightingRoller

(extruding) Centrifuge Hydraulic

Press Screw Press

Dryness of GARI 9 6 2 8 8 Quantity of GARI 8 10 8 7 1 Durability 8 8 6 10 10 Cost 7 5 9 8 8 Safety 6 4 9 5 10 Size/Weight 6 3 9 5 7 Amount of Power Requirement 5 1 4 9 6 Ease of Assembly 4 6 7 4 7 Ease of Maintenance 3 5 8 5 7 Weighted Total 319 373 400 397

Based on the design matrix shown in Table 4.2, the hydraulic press was the best design

from the presented alternatives. In conjunction with the lists of advantages and disadvantages given above, the hydraulic press was chosen as the juice extraction design. 4.3.3 Mechanism to transport cassava between stages

Between the grinding and pressing stages, a mechanism is needed to transport the ground cassava. The current process uses wheelbarrows, buckets, and burlap sacks. A new mechanism must be simple while ensuring that very little cassava is lost during the process. Four alternative methods were developed to move the cassava between stages including a conveyor, air to blow cassava, gravity, and burlap sacks.

4.3.3.1 Conveyer

A possible solution is to move the cassava using a conveyor from one stage to another. This solution would be a moving ramp that would bring the ground cassava from the exit of the grinder to the press. The conveyor would be designed to transport enough cassava as to not cause back-ups in the overall process.

Use of a conveyor would require a large energy usage. This amount of energy will probably be more that what can be provided by human power. Also, the grinder and the press will not run at the same rate which would make for bottle necks on the conveyor. For there reasons, a conveyor was not chosen as the best design for a transport mechanism. Additional advantages and disadvantages of this system are listed below.


• Make transfer easy • Expensive • Could be hand crank or gravity conveyor • Bulky • Easy incorporation • Heavy • Allows distance between machines • Requires power

4.3.3.2 Air to Blow Cassava

Another possibility is to use air to blow the cassava from one stage to another. The ground cassava would be blown through a tube into the press driven by an air compressor. To make this process possible, an air compressor would have to be incorporated into the design. This would increase the cost and complexity of the design as well as be another component that would have to be powered by human-power. For these reasons, the air blower

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was not chosen as the transport mechanism. Additional advantages and disadvantages of this system are listed below.

Advantages Disadvantages • Could be incorporate with other processes • Troubleshooting • Simple • Reliability • Consistent Conditions • Would require a lot of power • Might not work when cassava is wet

(before processing process) 4.3.3.3 Gravity

Another alternative is to use gravity to move cassava between stages. The grinder would have to be elevated above the press. The ground cassava would flow directly into the press from the grinder’s heighten elevation.

To use gravity, both the grinder and press would need to have similar cycle times, to avoid creating a new bottleneck in the process. Knowing that pressing will need a larger run time than grinding, gravity was not chosen as the final design. Additional advantages and disadvantages of this system are listed below.


• Free • Simple

• Reliability (cassava would stick to walls)

• Machines must be linked 4.3.3.4 Burlap Sacks

Another alternative solution for moving cassava is to use burlap sacks, which is the process currently being used in Uganda, similar to the one shown in Figure 4.10. This would involve filling the burlap sacks with ground cassava and manually moving sacks of cassava from the grinder to the press. The burlap sack could then be dumped out into the press or placed directly into the press and the juice would run through the sack leaving ground, pressed cassava in the sack.

Due to the simplicity of using a burlap sack for transport, the process was chosen as the best transport mechanism. Extra energy does not have to be mechanically created. Additionally, burlap sacks are already in use, making this design more culturally friendly. Additional advantages and disadvantages of this system are listed below.


• Low Cost • Physical Labor • Simple • Less efficiency • Already in use • Filters the juice

• Leaves room for accidents

5. Feasibility Analysis 5.1 Availability Attention has been given to the local availability of cassava for testing purposes and several steps have been taken to ensure that there will be a supply of the tuber in the spring when

Figure 4.10: A burlap sack

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larger scale testing becomes necessary. First of all, cassava can be regularly purchased at Meijer for approximately $2/lb. The cassava sold at Meijer is grown in Ecuador, where the plant is called Yuca. The tubers are smaller than the ones grown in Uganda but otherwise similar to the Uganda tubers. The Ecuadorian product will meet the testing requirements. Additionally, Yuca can be purchased from Meijer shortly before testing is to be completed to avoid spoilage before the experiment can be completed.

Second, cassava stakes (the root form of seed) have been purchased from Puerto Rico and planted in a local greenhouse (see Figure 5.1). Cassava takes approximately six months to grow, so the cassava is expected to be mature in the early spring of 2006.

Additionally, as part of an experiment, potatoes were tested as a possible substation for cassava (see Appendix B for more information). This substation would be made because potatoes are less expensive and more readily available than cassava. The potatoes were ground over coarse wood files with a teeth height of approximately 1mm. The potato grindings were compared to cassava grindings. Potatoes are moister than cassava and therefore would be a good substation for testing the pressing stage. Also, through the experiment, the potato grinds into a finer pulp than the cassava. This makes potatoes an undesirable substation for the grinding stage where quality needs to be controlled, however can be used for preliminary tests. 5.2 Cassava Processing Several experiments were performed to confirm the feasibility of processing cassava into Gari. These experiments were designed to test grinding, pressing, and drying. 5.2.1 Grinding Feasibility

Grinding was tested with an electric kitchen food processor (see Appendix E for more information). To replicate the current process, the cassava was peeled and washed before being put into the food processor. The cassava was then cut up into chunks that would fit into the food processor and ground until the cassava was close to the desired size of Gari. This experiment showed that cassava could be easily chopped up using a standard device with little effort as well as showed that the food processor was capable of grinding cassava to the desired size. However, difficulty was encountered in consistently producing the desired size.

To show that the cassava could be consistently ground to the same size, a second experiment was performed. The peeled and washed cassava was grated repeatedly over a very coarse wood file with teeth of approximate 1 mm height (see Appendix B for more information). Using this method, the ground cassava was consistently the same shape and size. Additionally, a file was constructed out of a wood board and screws (see Appendix F for more information), which produced coarse ground cassava. This experiment proved the manufacturability of a grinder. These experiments proved that cassava can be ground up consistently, a quality similar to that of Gari can be achieved, and a grinder can be manufactured. All of these things prove that the grinding stage is feasible. 5.2.2 Pressing Feasibility

The next set of experiments tested the feasibility of pressing ground cassava to extract the juice. Initially, ground cassava was squeezed in a garlic press and the juice was collected (see Appendix E for more information). The juice removed was compared to the mass of the wet cassava to determine whether raw cassava contained enough juice to merit a juice collection

Figure 5.1: Growing Cassava

14

system. After completing the experiment, a moisture ratio of about 40 wt% was found between the mass of the juice collected and the mass of the raw cassava pressed. Additionally, research showed a moisture ratio of up to 70 wt%13. Both of these amounts were determined to be large enough to justify the design of a juice collection device. Another variable in the pressing stage is the amount of force and pressure needed to extract various quantities of juice. To test the values, another experiment was completed (see Appendix G for more details). A measured amount of ground cassava was placed into a garlic press. Force gauges were attached to the handle of the garlic press and the handle force was measured through the gauges. Different forces applied to the handle were kept constant over 30 second intervals over two minutes. The juice was collected over this time period and measured. An analysis of the data, as seen in Figure 5.2, shows that the rate of juice removal is proportional to the amount of force applied to the handle. The volume of juice that remained in the ground cassava at the end of the two minutes also varied proportionally to the amount of force applied during pressing. This experiment shows that a significant amount of juice can be removed using a relatively strong force over a short period of time, or by using a lesser force for a longer time period. The results of a literature survey suggest that the process is pressure dependent and that pressure changes above 172.4 kPa do not affect the amount of juice removed.14 A final pressing experiment was completed by placing ground cassava between a weight and a hydraulic jack (see Appendix D for more details). This test proved that the chosen design removes significant amounts of juice from the ground cassava. An additional part of the pressing feasibility deals with the potential uses of juice after collection. Currently, after the ground cassava is pressed, the juice soaks directly into the ground without being collected and used. After communicating with contacts in Uganda, there are many uses for cassava juice after collection in the pressing stage including glues, industrial starch, and industrial alcohol15. With these possible uses for the juice, the scope of this project will include collecting the juice; however allow the operators to treat and use the juice according to the best needs of the area. 5.2.3 Drying Feasibility The final experimental stage was to test the drying of cassava using various methods including microwave, stove, oven, and warm storage. Most methods of drying had similar results of the cassava becoming a cake-like texture and becoming very sticky which are undesirable characteristics for Gari. The only successful drying method was placing pressed cassava over medium heat on the stove while consistently stirring similar to the process currently being used in Uganda. This process produced Gari that was dry and not sticky. These experiments determined that designing a mechanized process would be complicated. The process would have to dry the cassava below the required 14% moisture content while making sure not to let the cassava turn

13 Taiwo, 90. 14 Ajibola, 540. 15 Omanyo.

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

20 40 60 80 100 120

Time [s]Ju

ice

[mL]

10N20N30N50N70N

Figure 5.2: Force Required to Remove 3 mL of Juice from Wet, Ground, Cassava

15

sticky.16 Because of the complicated nature of each of the parts of the Gari making process, the decision was made to only focus on the grinding and juice extraction stages. 5.3 Quality Assessment

Contacts in Uganda described the size requirements of Gari particles as being between the size of a period in 14 and 24-point font (shown in Figure 5.3). To confirm this description, Gari was purchased from a local store, Saigon Market.17 The description from Uganda matched the Gari from Saigon Market. Therefore, the grinding machine will be designed to produce particles which match the size of the locally purchased Gari. 5.4 Funding / Material Gathering

An additional aspect of feasibility is gathering enough funding and materials to manufacture and test a prototype. Along with the $300 given to the project by the Calvin College Engineering Department, additional resources will be sought.

6. Project Management

The project has been divided into subtasks that can be distributed among the members of the group to ensure that all deadlines are met. Each team member has been assigned responsibility for certain organizational and engineering related tasks for the duration of this project. The major organizational tasks are: document organization, schedule, budget and monthly budget reports, website, and procurement. As part of managing the project, weekly meetings are scheduled to update members on the progress made by individuals. Meeting times allow other members to contribute ideas and voice concerns as well as keep group members on schedule. 6.1 Group Organization “Got Juice?” will divide up the main responsibilities for the two stages of grinding and juice extraction between the group members. Steve Krueger and Jeff Blech will be responsible for the juice extraction stage and Joshua Cypher, Kayt Vincent, and Joyce Vander Weide will be responsible for the grinding stage. Joshua Cypher will also serve as a liaison between the two groups and will assist the juice extraction group as necessary. 6.2 Document Organization

“Got Juice?” is keeping electronic copies of all research documents, correspondence, assignments, presentations, and designs on the X: drive. Paper copies of all items that have been handed in, along with drawings are also being kept in a team design notebook that will be stored at the team work station. Steve Krueger is responsible for the organization of the group’s paper documents and the electronic copies of the notes. He is also responsible for organizing the design notebook. Joshua Cypher is responsible for maintaining and organizing the team folder on the X: drive.

6.3 Schedule

Microsoft Office Project was used for scheduling which was done in Gantt chart form (see Appendix H). The schedule is a tool that “Got Juice?” will use to track progress and finish the project before the May deadline. The schedule gives visibility as to when tasks must be started and completed. The Gantt chart also shows which tasks overlap and are dependent on one

16 Taiwo, 90. 17 609 28th St SE Grand Rapids, MI 49548 (616) 245-5851

( . . ) Figure 5.3: Gari size

16

another. Kayt Vincent will be in charge of updating the schedule regularly and ensure that the plan is followed. 6.4 Budget

Joyce Vander Weide is in charge of updating the budget and composing the required monthly budget reports.

The prototype budget, seen in Table 6.4.1, shows anticipated costs of building a prototype of both the grinder and press. These numbers are estimates and will become more accurate as design continues.

Material Unit Cost Quanity Total CostGrinderFrame/Structure

Legs 2 X 1 Steel Tube $ .50/kg 15 kg $7.50Cross bars 1 X 1 Steel Tube $ .50/kg 10 kg $5.00Top Cover sheetmetal $25.00 1 $25.00Hopper sheetmetal $20.00 1 $20.00Side Panels sheetmetal $5.00 4 $20.00Brackets steel $1.00 10 $10.00Fasteners steel $0.10 50 $5.00Drive Guard steel $5.00 1 $5.00

ComponentsCrank Mount steel $10.00 1 $10.00Grater mount steel $10.00 2 $20.00Bearings Stainless Steel $10.00 2 $20.00Crank bicycle parts $30.00 1 $30.00Belt V-belt $5.00 1 $5.00Pulley V-belt pulley $15.00 2 $30.00Drive Shaft 1" OD $25.00 1 $25.00Teeth for disk wood screws $0.15 50 $7.50Spinning disk Aluminum $1/lb 15 lb $15.00

PressFrame/Structure

Legs 2 X 1 Steel Tube $ .50/kg 17 kg $8.50Cross bars 1 X 1 Steel Tube $ .50/kg 15 kg $7.50Brackets steel $1.00 10 $10.00Fasteners steel $0.10 25 $2.50Base sheetmetal $5.00 1 $5.00

ComponentsHydraulic Jack retail $130.00 1 $130.00Top Stage wood $20.00 1 $20.00Piston wood $25.00 1 $25.00Guide frame Steel Bar $ .50/kg 1 kg $0.50L-Brackets Steel Angle Iron $ .50/kg .5 kg $0.25Ratchet metal rod $5.00 1 $5.00Platform for jack sheetmetal $10.00 1 $10.00Juice Trough rubber tube $5.00 1 $5.00Sacks for transport burlap $10.00 1 $10.00

TOTAL $499.25

Table 6.4.4 Budget

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6.5 Website The team website (http://engr.calvin.edu/SeniorDesign/SeniorDesign05-

06/team03/index.html) contains information about the team as well as most documented information completed at various time throughout the academic year. Jeff Blech is responsible for keeping the website up to date and accurate. 6.6 Procurement

Another aspect of managing the project is part procurement. Joshua Cypher is in charge of ordering, tracking, and receiving the parts required for the project. He will facilitate a smooth flow and supply of parts to simplify prototype construction in the spring. 7. Design 7.1 Grinder Design

As discussed in section 4.2.1, the chosen design incorporates a disk with teeth on one flat surface, rotating rapidly (see Figure 4.7). The spinning disk will be hand powered. To give the ground cassava time to move off the disk, only half of the teeth will be used to grind the cassava at any one time. The washed and peeled cassava will be placed into a hopper above the spinning disk and will be pressed onto the disk using a plunger. The teeth of the disk will then grind the cassava into a coarse pulp while the rotating motion will use centripetal force to push the cassava over the edge of the disk (Figure 7.1). The cassava will drop off of the disk and fall through a chute into a collecting device such as a sack. Once in the container, the cassava will be transferred to the juice extraction machine. Drawings of the preliminary design and pictures of the cardboard prototype are shown in Appendix I.

7.2 Juice Extraction Design

The chosen juice extraction design is a hydraulic press, which will be manually loaded and jacked up. The cassava will be placed in a burlap sack and placed on top of a cylinder head. Using an easily available 1.5 ton hydraulic bottle jack, the cylinder head will be driven upwards into a cup that is welded to the same frame as the jack (as shown in Figure 7.2). Both the head of the cylinder and the cup will have a slight curve to facilitate the process of the juice running out of the cassava. Pictures of the initial prototype and more detailed CAD renderings are available in Appendix J.

8. Conclusions

The experiments described in the preceding pages clear show that the toothed spinning disk is a feasible option for the grinder. The experiment using wood files proved the possibility of controlling the quality of the cassava using different size teeth. A similar concept is currently used in commercially available

household juicers, which further supports the conclusion that using a spinning disk with file teeth will effectively and efficiently grind the cassava.

Figure 7.2: Pressing

Figure 7.1: Grinding Device

18

Similarly, tests show that the hydraulic press is the most effective method of removing juice from the cassava under the given design restrictions. Using such a press will produce cassava of the appropriate dryness and much more quickly than the current screw press.

The largest obstacles in the design process have been shown to be the manufacturing of a toothed spinning disk, and designing a sufficiently strong frame for the press.

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9. References Ajibola, O. O. "Mechanical Dewatering of Cassava Mash." Transactions of the ASAE 30, no. 2

(1987): 529-42. GourmetSleuth.com. "Molcajete (mortar and pestle)." The Gourmet Food & Cooking Resource.

http://www.gourmetsleuth.com/mortarpestle.htm (6 December 2005). Nutrition Data. "Potato, baked, flesh and skin, without salt." NutritionData.com.

http://www.nutritiondata.com/facts-001-02s024y.html (5 December 2005). Ogwok, Jacob. E-mail to the author. 24 Oct. 2005. Oje, Kayode. "Moisture Content Determination for Cassava: Development of Direct and Indirect

Methods." Agricultural mechanization in Asia, Africa, and Latin America 24, no. 1 (1993): 51-54.

Okigbo, Bede N. "Nutritional implications of projects giving high priority to the production of

staples of low nutritive quality." The United Nations University Press: Food and Nutrition Bulletin 2, no. 4 (1980). http://www.unu.edu/unupress/food/8F024e/8F024E01.htm#Food%20and%20nutrition%20policy (8 December 2005).

Omanyo, Davis. "Gari Production Project." E-mail to the author. Aug. 2005. Taiwo, Kehinde A. "Technology Choice and Technical Capacity in GARI Production." Food Reviews International 17.1 (2001): 89-107.

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10. Appendices Appendix A: Juicer Experiment…………………………………………..21 Appendix B: Wood File on Cassava Experiment………………………...22 Appendix C: Centrifuge Experiment………………………………….….24 Appendix D: Hydraulic Pressing of Cassava……………………………..27 Appendix E: Experimenting with Cassava……………………………….29 Appendix F: First Teeth Test………………………………………….….31 Appendix G: Cassava Pressing Force Experiments………………………32 Appendix H: Schedule……………………………………………………33

Appendix I: Grinder drawings……………………………………………34

Appendix J: Press drawings………………………………………………37

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Appendix A: Juicer Experiment Procedure:

Peel and wash cassava. Cut the cassava into pieces that can fit into the juicer. Put a cup by the spout where the juice will come out. Put a bowl by the location where the ground cassava will come out. Turner the juicer on. Drop the cassava pieces into the juicer. Use the plunger to push the cassava into the spinning disk. Results:

The juicer gave promising results. The experiment showed that the spinning disk is a feasible idea. The spinning disk chopped the cassava into the desired size. The ground cassava was on the drier side, but not as dry as when the cassava was pressed. Juice was also collected.

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Appendix B: Wood File on Cassava Experiment Date of experiment: 11/19/2005 Done by: Josh Cypher Goals: 1. See how cassava grinds when ground by 3 types of wood files with varying characteristics

2. See how well a potato relates to cassava on when ground up in a similar manner by the 3 wood files Procedure: Peel and wash cassava/potato Move the cassava/potato over one of the 3 files until an adequate amount of ground cassava has been collected Compare the ground cassava from the files to the desired size Test the clensablity of the file by running water over the files and notice how easy the cassava comes off the file File #1: Wood handle, teeth 1 mm tall at right angle to surface Cassava: The ground cassava is meshed together on the file, but it still cuts Grinds cassava finer than desired which means that we will want coarser teeth in the final design When cassava is wet, the file cleans very easily (comes off under facet easily) When the cassava has been allowed to dry on the file, it comes off much harder but still does not require scrubbing Potato: Potato is more moist than cassava Potato contains less fiber than cassava Potato is ground into a moist pulp (more moist than cassava) When potato is wet, the file cleans very easily File #2: No handle, teeth 1 mm tall with an under cut Cassava: File got filled with cassava, but continues to cut as with File #1 The size of the cassava is still smaller than the desired size of GARI (size similar to File #1) When cassava is wet, the file cleans easily under running water (does not come off as fast as File #1 but does not need any scrubbing) When the cassava has been allowed to dry on the file, it comes off much harder and almost requires scrubbing Potato: Potato is ground into a moist pulp (similar to File #1) When potato is wet, the file cleans easily (running water will remove all ground potato)

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Appendix B: Continued File #3: No handle (black), with 1 mm tall teeth with holes Cassava: The cassava comes through as strings The cassava goes though the holes fairly easily The clean-up of the file is much harder since the cassava gets stuck in the holes Potato: The potato comes through as moist strips Goes through holes very easily Clean-up is more difficult than other files due to the holes Analysis on Files: The files seem to grind the cassava much finer than desired. In order to achieve the desired size and quality, coarser teeth must be used.

The file with the teeth at a right angle to the surface cleans easier than the file with an under cut with no difference in quality. Also, a file with the teeth at a right angle will be easier to manufacture than teeth with an under cut. The file with holes turns the cassava into strings rather than a gain. It is thought that even though the grinder will be spinning, some strings will still be produced Analysis on potatoes for use as cassava:

Potatoes will make a great substation for cassava in the pressing stage. Since potatoes have a higher moisture percentage than cassava, the potato will act as a higher goal to achieve for the pressing stage.

Potatoes will make an acceptable substation for cassava in the grinding stage. The potato seems to have less fiber than the cassava so the quality of the grinding stage will not be able to be evaluated with a potato however the rest of the process can be verified with the potato substitution.

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Appendix C: Centrifuge Experiment Senior Design Date of Experiment: 11/3/2005 Centrifuge Test Date of Meeting Review: 11/4/2005

Author: Josh Cypher

Normal Force Equation: F=mrω2 Experiment #1 Goal: Calculate the density of un-ground cassava Procedure: Take pieces of raw, un-ground cassava and place them into a graduated cylinder filled with water at a known volume. The displacement of the water will give the volume of the cassava which, along with the mass, will give the density. Results: Trial 1 Mass of un-ground cassava 4.9 g Volume displaced 4.5 ml Density Calculated 1.09 g/ml Trial 2 Mass of un-ground cassava 3.9 g Volume displaced 3.5 ml Density Calculated 1.11 g/ml Average density from both trials 1.10 g/ml Experiment #2 Goal: Calculate density of ground cassava Procedure: Take unpressed, ground cassava and place into a tablespoon. This volume along with the mass will give the density of ground cassava. This value should be less then, but close to, the density of un-ground cassava due to an increase in air and less moisture from the grinding process. Results: Mass of ground cassava (Trial #1) 15.20 g Mass of ground cassava (Trial #2) 16.50 g Mass of ground cassava (Trial #3) 15.70 g Average from Trials 15.80 g Average density of ground cassava = 1.07 g/ml

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Appendix C: Continued Experiment #3 Goal: Test to see if a centrifuge is possible to extract juice from ground cassava. A bicycle wheel spins at approximately 350 rpm, however most centrifuges spin between 1400-3000 rpm. This test will show whether significant moisture can be extracted to make the idea possible. Procedure: Take weighed amount of ground cassava. Place into cup on top of 4 layers of cheese cloth. Connect the cup to a rope. Spin the cup at a certain radius with a constant angular velocity. Determine force produced and amount of liquid extracted. (See next work sheet for diagram) Values: Total mass of ground cassava in cup = 65.5 g Distance from center of rotation to cassava = 13 inch Approximated rotational velocity = 230 rpm 24 rad/sec Estimated force produced on Cassava = 13 N Results: Got "some juice" out of ground cassava (actual amount was not measured). The left over ground cassava was still very moist, which proves that the centrifuge can not be used if it is hand powered. Additional Notes about procedure: The rotational velocity was hard to measure exactly due to the speed of rotation and the only instrument possible was the human eye. The estimated force produced was only 13 N for only 18 seconds. If either the force or time could be increased, more juice could be extracted. The 4 layers of cheese cloth held the ground cassava very well with no cassava falling into the bottom of the cup.

26

Appendix C: Continued

Figure C-1: Centrifuge experiment set up

Ground cassava Cheese Cloth

Cup

Rope

Extracted

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Appendix D: Hydraulic Pressing of Cassava Cassava Experiment - 11/12/2005 (Pressing of Cassava between car and jack) Instruments Scale Graduated Cylinder Food Processor Juicer Hydraulic Jack Jeff's Car 2 boards Cheese cloth Garbage bags Procedure

In this experiment, we ground up Cassava as in previous experiments. We weighed two portions of the ground Cassava. One portion was for a control experiment in a garlic press. The second portion measured was the part for the actual experiment. As a control, the small portion of Cassava was squeezed dry using a garlic press. The juice removed was measured to find the moisture content of the cassava sample.

For the pressing experiment, the large portion of Cassava was wrapped in cheese cloth and placed in a garbage bag. The end of the garbage bag was tied so that the juice would collect in the bag. Next the pile of Cassava was placed between two boards. The board on top of the cassava was in contact with the car and the board below the Cassava was placed on the jack. Finally the jack was raised up and the weight of the car squeezed out the juice in the cassava. The juice was collected and measured using the graduated cylinder. The experiment was performed 3 times. Results Constants mbowl = 61.3 g mplate = 75.7 g mpress = 16.3 g Experiment # 1 Control Results mcontrol = 6.1 g Vcontrol = 3 mL V/m = 0.49 mL/g Pressing Results Pressed dimensions Observations mcassava = 206 g t = 1 cm Vremoved = 59 mL L = 11 cm

Center was the most dry due to direct pressure from the jack

mpressed = 112 g W = 12 cm dry enough and fairly consistent V/m = 0.29 mL/g

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Appendix D: Continued Experiment # 2 Control Results mcontrol = 8.8 g Vcontrol = 3 mL V/m = 0.34 mL/g Pressing Results Pressed dimensions Observations mcassava = 189 g t = 1 cm Vremoved = 54.5 mL L = 14.5 cm

Same as in experiment 1, not as well centered

W = 8.5 cm V/m = 0.29 mL/g Experiment # 3

In this experiment, the boards were replaced with a C - bracket and a 2 X 2 block of wood. This is more representative of what we have in mind for our final design. Results were poor because the C-bracket we used was too big to allow the juice to drain well.

Pressing Results Pressed dimensions Observations

mcassava = 419 g t = 1.5 cm Came up on the edges Vremoved = 72.5 mL Still very moist V/m = 0.17 mL/g

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Appendix E: Experimenting with Cassava Senior Design Date of Experiment: 9/21/2005 Cassava/GARI cooking experiments Date of Meeting Review: 9/23/2005

Author: Josh Cypher

Observations about Cassava: Brown, rough exterior White inside Harder than a potato Smells like a green mango (not strong smell) When cut, moisture forms on outside ring of skin Skin somewhat waxy 2 layers of skin (hard brown outside layer, red/purplish inside layer) Minimum effort to extract most juice from cassava with garlic press A lot of effort to extract all possible juice from cassava with garlic press Easy to peel by hand once started Some samples looked like they had a pin size core

Experiment #1 Procedure: Peel and wash cassava. Cut cassava into pieces that will fit into a food processor. The food processor used has spinning blades. Results: The food processor ground cassava into desired size. The food processor was then used to do the grinding for other experiments.

Experiment #2 Procedure: Ground cassava in grinder and placed between napkin Results: Napkin becomes very damp

Experiment #3 Procedure: Use Garlic press to press juice out of cassava has hard as possible Results: About 1 tablespoon of ground cassava was pressed and about 0.5 tablespoons of juice was colleted.

Experiment #4 Procedure for experiment #3, but using a scale and graduated cylinder. Started with wet, ground cassava Results (** = tabulated value):

Tablespoon = 6.80 g Graduated Cylinder = 10.6 g

Strainer = 16.3 g Tablespoon with wet, ground cassava = 21.7 g

Liquid with Graduated Cylinder = 18.8 g Pressed Cassava with Strainer = 22.2 g

Wet and ground Cassava = 14.9 g ** Pressed Cassava = 5.90 g **

Liquid (mass) = 8.20 g ** Liquid (volume)= 7.70 ml

Density of liquid = 1.06 g/ml ** Moisture Ratio (by mass) = 0.550 **

Accuracy by conservation of mass = 0.946 **

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Appendix E: Continued

Experiment #5 Procedure: Start from raw cassava (with shell) and going through procedure in experiment #3 Results:

Cassava with shell = 60.3 g Cassava without shell = 51.7 g

Cup = 40.3 g Cup with pressed cassava = 64.2 g

Liquid with Graduated Cylinder = 35.0 g Shell = 8.6 g **

Pressed cassava = 23.9 g ** Liquid (mass) = 24.4 g **

Liquid (volume) = 22.8 ml

Density of liquid = 1.07 g/ml **

Moisture Ratio w/ shell (by mass) = 0.405 ** Moisture Ratio w/o shell (by mass) = 0.472 **

Shell Ratio (by mass) = 0.143 ** Accuracy by conservation of mass = 0.934 **

Experiment# #6 Procedure: Placed wet, non-pressed cassava over stove at low heat than in microwave Results: Came out of microwave as a "cake" that is sticky and yellowish

Experiment #7 Procedure: Place unpressed in oven @170°F for over 30 minutes Results: Became clearish and cake like. Peeled up from cookie sheet in pieces still a bit damp; not as yellow as from experiment #6.

Experiment #8 Procedure: Place unpressed in oven at high temperatures Results: Burned quickly

Experiment #9 Procedure: Placed pressed cassava over stove at medium heat for 5 minutes while being constantly stirred.

Results: Dried and stayed white and started to turn brown (assumed being burnt) and was removed

Experiment #10

Procedure: Pressed, dried cassava from experiment #9 was mixed with milk and sugar and tasted Results: Tasted like corn flakes

Experiment #11 Procedure: Took sliced cassava pieces and placed over stove at medium-high temperatures for 5-10 minutes. Sprinkled with seasoning. Results: Tasted similar to seasoned potato fries

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Appendix F: First Teeth Test Date of experiment: 12/6/2005 Author: Josh Cypher Goals: Test how well various teeth (screws through wood) produce desired size of ground cassava (use potato to simulate cassava) Procedure: Take two size screws and screw them into a piece of wood (one screw size was approximately 1/8" and the other was a little smaller). Move the potato over both sets of screws Collect, dry, and inspect the grindings Results:

The screws produced encouraging results. The potato grindings were a little larger than desired, however within a ballpark range. The smaller screw seemed to produce smaller grindings and therefore seems more desirable. We feel that with some more test of various sizes of teeth and possible alterations of teeth, the desired size can be achieved every time. Additionally, when the grinder is spinning at a fast rpm, the cassava will decrease in size additional amounts. This test validates the idea of using screws as teeth in our spinning disk design. Additional Note

After a few more teeth tests have been completed, an actual spinning disk is desired to be made in order to test the results of a spinning disk with teeth. This will probably be made out of wood and be smaller than the final design in order to save cost and time.

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Appendix G: Cassava Pressing Force Experiments Date: 10/18/2005 Procedure:

Take 1/2 tablespoon of ground cassava and put it into the garlic press. Use gage springs to measure the constant force applied to the garlic press. Apply the force for 2 minutes. Repeat experiment with several different forces. Collect the juice from the cassava when the force is applied. Every 30 seconds measure the amount of juice collected.

10 N 20 N 30 N

Time (s) Volume (mL) Time (s) Volume (mL) Time (s) Volume

(mL) 30 1.5 30 2.25 30 2.1 60 2 60 2.4 60 2.4 90 2.25 90 2.5 90 2.5 120 2.5 120 2.6 120 2.6

50 N 70 N

Time (s) Volume (mL) Time (s) Volume (mL) 30 2.5 30 2.25 60 2.8 60 2.5 90 2.9 90 2.5 120 2.95 120 2.75

Results:

After two minutes the force was increased so the maximum amount of juice could be collected. Subtract the amount of juice collect in 2 minutes from the maximum amount of juice collect, to get the residual volume.

Force (N) Maximum Volume (mL) Force (N)

Residual Volume (mL)

10 3* 10 0.5 20 3 20 0.4 30 3 30 0.4 50 3.25 50 0.3 70 3 70 0.25

* assumed this value Dimensions: Distance from gage spring attachment to the center of the cassava: 4.75 in Distance from gage spring attachment to the fulcrum: 6 in

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Appendix H: Schedule

ID Task Name Duration1 Define Project 6 days

2 Objective Goals 61 days3 Create Goals 6 days

4 Update Goals 1 day

5 Update Goals 1 day

6 Brainstorm 1 day

7 Research 38 days8 General Background 25 days

9 Current Juice Extraction Methods 13 days

10 Current Grinding Methods 13 days

11 Possible Alternatives 7 days

12 Schedule 151 days13 Create Schedule 5 days

14 Update Schedule 3 days

15 Update Schedule 1 day





20 Meet W/ Hillcrest CRC 0 days

21 Alternatives Solutions 36 days22 Create Alternative Soln's 3 days

23 Analysis of Alternative Solutions 18 days

24 Decision 10 days25 Decide on Matrix Weightings 1 day

26 Construct Decision Matrix 1 day

27 Testing 7 days28 Preliminary Centrifuge Experiments 1 day

29 Preliminary press experiments 1 day

30 Preliminary Grinding Experiments 1 day

31 Choose best solutions 1 day

32 Christmas Break 12 days

33 PPFS 59 days?34 Draft Report 49 days?35 Experimental Proceedures 39 days?

36 Literature Research 21 days

37 Feasibilty Evaluation 5 days

38 Scope 5 days?

39 Design considerations 10 days?

40 Project Management 8 days?

41 Draft Due 0 days

42 Final PPFS 6 days43 Revise Report 6 days

44 Final Draft Due 0 days

45 Preliminary Prototype 15 days46 Secure Mat'ls 3 days

47 Construction 5 days

48 Testing 3 days

49 Results Analysis 2 days

50 Design 61 days51 Preliminary 35 days52 CADD Draw ings for Design 35 days

53 Preliminary Stress Analysis 6 days

54 Redesign 56 days55 Address Preliminary Prototype Issues 4 days

56 CADD Draw ings Modifications 50 days

57 FEA Anaylsis 14 days

58 Spring Break 5 days

59 Assembly Manual 28 days60 Assembly Instructions 21 days

61 Test Manual 2 days

62 Revise 5 days

63 Final Prototype 28 days64 Build Final Prototype 28 days

65 Final Paper 64 days

66 Team Date 0 days

67 Administrative 163 days?68 Poster 0 days

69 Project slide 0 days

70 Website 0 days

71 Preliminary Budget 0 days

72 Refined Task Specif ications 0 days

73 Project Brief 0 days

74 Budget 142 days?75 Create Budget 1 day?

76 Update Budget 1 day?

77 Reports 130 days78 Budget Report 0 days

79 Budget Report 0 days






85 Presentations 38 days?86 Presentation 1 4 days?87 Pow er Point 2 days?

88 Group Practice 3 days

89 Presentation 1 0 days

90 Presentation 2 8 days?91 Pow er Point 8 days?

92 Group Practice 3 days?

93 Presentation 2 0 days

10/27

11/28

12/9

10/14

9/3010/5

10/1410/31

11/411/11

11/1512/15

1/132/15

3/154/14

5/15

10/11

11/28

September October November December January February March April May

34

Appendix I: Grinder drawings

Figure I-1: Preliminary cardboard model (closed) of the grinding chamber

Insert Cassava

Collect Ground Cassava

A plunger would fit in here to apply pressure on the cassava

35

Appendix I: Continued

Figure I-2: Preliminary cardboard model of the grinding chamber open with disk inside

Hinged on one side for accessibility

Spinning disk mounted inside the device

The disk will grate and fling the cassava to the sides. It would then fall out of the chute due to gravity

36

Appendix I: Continued

Figure I-3: CAD drawing of the closed grinding chamber Figure I-4: CAD drawing of the spinning disk

37

Appendix J: Press drawings

Figure J-1: Preliminary press model with the piston pushed up

Steel Frame

L-bracket attached to piston as a glide

Cross bars for added strength

38

Appendix J: Continued

Figure J-2: Preliminary press model with the piston down

Put ground cassava in burlap sack. Place the sack on the piston

Piston moves up to squeeze the juice out of the cassava

Piston moves down and cassava is removed

39

Appendix J: Continued

Figure J-3: CAD drawing of the press with the piston pushed up

Figure J-4: CAD drawing of the press with the piston down

Trough to collect the juice

Hydraulic Jack

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