Baobab and Moringa Seed Oil Extractor

Baobab and Moringa Seed Oil Extractor
    Kyle Walker, Bill Nash, Manan Gill, Andrew Moyer, Katherine Kennedy, Katie Plain,
                       Michael Schrenk, Safa Alsinan, Jesus Colon

1. ABSTRACT

       This team worked to research and build a prototype for a machine to extract oil from
baobab and moringa seeds in order to help a Beninese cooperative. The project began with the
research and initial ideas of the former group, and proceeded with further research and testing.
After gaining the proper knowledge, a prototype was designed and created.

2. INTRODUCTION

        Beginning in 2005, the Baobab PSU Initiative was created as an attempt to aid a
cooperative, or small village, in Benin, Africa. This project, continuing from another ENGR 493
project from Fall 2011, seeks to develop a workable seed oil extractor design and prototype. This
report details the research and designs generated by two initially separate groups and the
prototype they collaborated on. Challenges faced during the course of this project include
creating a manual human powered device, lacking definitive information on a screw press,
limited manufacturing opportunities, and the integration of the two teams.

3. GOALS

        This project was broken into two phases: a design phase and a prototyping phase. In the
first phase, two separate teams were tasked with designing a baobab and moringa seed oil
expeller to be prototyped and ideally sent over to the seed oil cooperative.
        The goals of the design phase were focused around the user in Benin. The oil extractor
would ultimately reduce the amount of time required to fully extract the oil from the baobab and
moringa seed. The oil would be sufficiently filtered of cake and contaminants, thus enhancing the
quality when compared to current extraction methods. The design would contain simple parts
that are easily interchangeable, replaceable and could be found in local areas.
        The design process for the first phase started by evaluating existing information and
conducting further research. After completion, brainstorming sessions took place to generate
new concept ideas. Next, customer needs were examined which helped to determine the final
concept selection. An Analytic Hierarchy Process software tool was applied to the customer
needs to create a weighted scale. Customer needs included the efficiency, sustainability,
portability, feasibility, ergonomics, size and cost of the oil extractor. After evaluation, it was
discovered that efficiency of the machine far outweighed other customer needs. With this in
mind, each generated concept was appraised based on the weighted scale, and the final design
with the highest score was an oil extractor that utilized a gear box.

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In the second phase, the two teams came together to form one large group and
construct a prototype. During the second phase, aspects of the two individual designs were
incorporated into one final design.
       The goal of the second phase was to integrate the two final concepts from Team A (gear
reduction) and Team B (hand­powered) into an official prototype that would be manufactured. 4
weeks and a budget close to $500 were given for completion of said goal.

4. RESEARCH/BACKGROUND

         The baobab tree is found in Australia, Madagascar, Arabian Peninsula, and in Africa,
where this project in mainly focused. The baobab tree produces seed pods which contain a
multitude of seeds, from which oil can be extracted. The seeds are initially soft and oil­rich, but
dry out and harden over time, so extraction must take place soon after harvesting. This seed oil
is full of rich vitamins such as A, B, E, and F, which are valuable elements for skin and hair
products. It also contains Omega 3, 6, and 9 fatty acids and is valued around $300 per liter of oil.
         The moringa seed is very similar to the baobab seed, with minor differences in the shape
and size. The moringa tree is found in South America, Sri Lanka, India, Mexico, Malaysia,
Indonesia, the Philippines, and also throughout Africa. Its oil is considered one of the most stable
of naturally produced oils, which makes it excellent for cooking and preservatives. The Moringa
seed oil is valued at about $70 per liter, and its medicinal uses are being thoroughly explored.
         The most common method of seed oil extraction currently used among African
communities is the mortar and pestle, a slow, arduous process with an estimated maximum
yield of only between 20­30%. Several machines have been produced for the purpose of seed
oil extraction, but most require an external power source. This makes them far from ideal for
use in small African communities, which often have limited or nonexistent access to electricity.
A few manually­powered devices do exist (most notably the Piteba), but their efficiency is
somewhat poor. Thus, the seed oil extraction process in Africa is in dire need of improvement.
         To supplement the gathered research, a compression test was performed. The
compression test proved that the Baobab seeds need roughly twice the amount of force to
extract oil as compared to the Moringa seed. This was an essential step towards designing a
device.

5. INDIVIDUAL DESIGNS

Team A
        Team A’s first concepts consisted of a lever mechanism that would allow the user to
manually crank the device in order to crush the seeds. The main concern with this prototype was
that a person would not be able to apply the proper amount of grinding force to effectively smash
the Baobab seeds.
        The second concept was a bicycle wheel and a foot pedal. When evaluating the existing
research, bicycle parts were a prominent subsidy in Benin, where the Baobab Seed Oil Extractor
is to be implemented.

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The final and most practical concept Team A came up with was the gear reduction
method. Gears are often used to either increase the output speed or force in a machine
compared to the input. However, in order to increase the output force one must sacrifice the
output speed, or vice versa. One common example where gears are utilized include the
transmission of many simple machines, such as in a penny press.
         Novel penny presses found in many amusement parks are able to imprint a design onto a
penny by the simple turn of a wheel. Pennies, however, are not often regarded as malleable or
soft (i.e. they cannot be bent by hand). Penny presses apply the use of a gear box and concept
of gear reduction to increase the force of the press without causing the user any trouble rotating
the wheel.
         Group A’s final design included the concept of gear reduction coupled with a human
powered, stationary bicycle. The user would pedal the bicycle that has a belt replacing a
common metal chain. The belt is connected to a gear box located where the back set of gears
normally are. The gearbox would ramp up the force, allowing the connected screw to turn with
more torque (and ultimately create more pressure). Seeds are fed through a hopper connected
to the top of the oil press. As the seeds are loaded into the device, the screw turns, pushing the
seeds along while creating large amounts of pressure that press the seed. The oil that is
expelled is filtered through a screen, and the seed cake comes out through the end cap. The end
cap is adjustable so that it can be screwed on more tightly, increasing the amount of internal
pressure if needed.

Team B
         Team B came up with two main iterations of the press design, both centered around
making the device as user­friendly as possible. The main consideration here was that hand
cranking for the entire day is an exhausting chore for the members of the baobab cooperative, so
some other power input would be ideal.
         The first design attached the drill to a bicycle trainer since bikes and bicycle parts are
common in Benin and Morocco. A bicycle trainer has a simple frame to make and can work with
any bike, making the design modular enough to fit any african bike. The back wheel of the cycle
rests against the resistance cylinder of the trainer, which is directly connected to the shaft of the
drill. This design would provide very high rotations per minute for pressing out seeds, but
suffered from a lack of power: if the force required to press the seeds exceeded the friction force
between the wheel and the cylinder, the wheel would slide and kinetic friction would decrease the
force even more. Additionally, although this design allowed the user to take advantage of bike
gearing to drastically increase the RPM, there are optimal RPM ranges for most seeds that it
would undoubtedly exceed. In other oil presses those ranges are around 50­70 RPM for various
seeds. This design would have exceeded any sort of reasonable range.
         The final design from group B sought to take into account the prominence of bicycles in
Benin in a different way. The device was designed so that the frame, a simple triangular design,
could easily be made from bicycle tube frames. The power was input from a bicycle gear and
crank at one end of the frame and transmitted through a chain to a second gear at the base of
the frame. This second gear turned the shaft of the drill press. As is the case with most drill
presses, the seeds would be fed in through a hopper at the top, crushed against either bars or
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rings on the inside of the casing, and the cake would come out the end at a screw­on cap.

        This design’s main feature was that one arm of the triangular frame would be telescoping
or on a hinge, depending on ease of use and manufacturing. This would enable the crank to be
fixed at a variable height, which enables the use of both hand cranking and peddling. Users over
at the Baobab cooperative would thus have a much easier time using the machine for extended
periods. This design had major portability issues that severely hampered its effectiveness,
despite not needing a bike. It was scrapped because it was found the users heavily prefer hand
crank mechanisms, making the main feature far less attractive.

6. FINAL DESIGN

Overview
        The final screw press design consists of a steel tapered screw encased in a steel
cylinder. The inside of the cylinder will be lined with either steel bars or rings. A cap has been
welded onto one end of the cylinder, while the other end remains open so that it may slide into
place over the screw. The cylinder, when in place, rests on a wooden stand. A hand crank, to
which the screw will be attached, will be fixed to this stand. The machine will be operated by
feeding baobab or moringa seeds into the cylinder through a hopper and turning the hand crank.
The screw, when turned will feed the seeds along the threads. Due to the tapered design of the
screw, the seeds will get pressed against the bars or rings and the oil will be extracted. The oil
will seep through the gaps between the bars or rings and drain through holes in the cylinder to be
collected, while the excess seed material (called cake), will be expelled through the cap.

Screw
        The screw (the only part of the machine, which, unfortunately, has not yet been acquired)
will be constructed of stainless steel and have a constant outer thread diameter of approximately
3 in. (most likely it will be slightly less, so that it fits comfortably within the casing) and a length of
about 1 ft. The inner shaft diameter will be tapered from about 1.5 in. near the hopper to about
2.5 in. near the cap. This way, as the seeds move along the threads, they are crushed against
the bars/rings to extract oil.

Casing
         To encase the screw, a 1 ft. long steel hollow cylinder was constructed. The cylinder
has an outer diameter of 4 in. and an inner diameter of 3.5 in. (0.25 in. thickness). Several holes,
drilled through the casing at one end, allow for drainage of oil. Two slightly larger holes allow for
the bars, discussed below, to be hammered out of place and removed in addition to providing oil
outlets. This end has a steel “cap” welded on one end of it, while the other end is left open for
the insertion of the screw. At the open end, a hole is drilled into the top of the casing for insertion
of the “hopper,” which is simply a plastic funnel into which seeds are poured.

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Cap
        The cap has a circular arrangement of six holes drilled into it, through which the cake is
expelled. The holes are threaded, so that they may be blocked with hand screws as desired.
This allows the user to control the amount of cake that is expelled, and thus the level pressure in
the chamber. This is especially useful when switching between baobab and moringa seeds,
which require different pressures during extraction.

Bars
        Through research it was discovered that in order to separate the seed oil from the seed
cake, either bars or rings would be needed as a filter between the screw and the holes in the
casing. The bars are rectangular pieces of steel that fit tightly along the inside of the casing. In
theory, the oil will seep between the bars and flow out the holes drilled in the casing. The cake
cannot pass through the spaces between the bars and is instead expelled through the cap, as
described above. The set of bars consists of eleven identical long bars, two shorter bars which
are cut so as not to cover the hopper­hole, and one thinner “keystone bar” that is inserted last
and hammered in. The main benefit of the bars is that they hold themselves in place without a
clamp or screws. The downside is they are somewhat hard to put in place.

Rings
        The rings could be used as an alternative to the bars described above. The rings simply
slide into the casing, and would thus be easier to put in and take out than the bars, allowing for
easier cleaning. However, they would also require either a clamping device or screws at the
capless end of the casing in order to stay in place. 10 standard rings (width: 1 in.; outer
diameter: 3.5 in.; inner diameter: 3 in.) and one “end” ring (width: 2 in.; same inner and outer
diameter) were cut, filed, and buffed from a hollow bar so that they would fit exactly within the
casing. A hole has yet to be drilled in the “end” ring so as not to obstruct insertion of the hopper.
Also, should using screws be chosen as a means of holding the rings in place, holes must be
drilled and tapped in the “end” ring as well as the casing. This would enable the final ring to be
screwed in place through those holes.

Stand
        A stand was constructed out of wood to support the casing and the hand crank. Two
curved steel bars are drilled to the top of the stand, on which the cylinder rests. The hand crank
will be drilled on to the back of the stand to hold it in place and ensure that it is aligned with the
center of the cylinder. A red mahogany finish was applied to the wood.

Hand Crank
      A trailer winch was purchased to serve the purpose of a hand crank. The winch is

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constructed out of steel and has a 600 lb capacity. The main axle of the winch was replaced
with a steel shaft, which was welded to the winch’s gear. This way, the shaft rotates with the
gear. The tapered screw will eventually be welded to the shaft, so that the hand crank can be
used to turn the screw.

7. MOVING FORWARD

        Obviously, the prototype has not yet been completed, so the goal first and foremost is to
obtain the tapered screw and assemble to final product. Beyond that, the current team or teams
in the future must look into improving the current design. Since the prototype has not reached a
stage at which testing can be conducted, it is impossible to accurately assess its level of
success. However, suggestions can be made regarding solutions to possible problems that
may arise. One of these is the possibility that a sufficient amount of force may not be generated.
We conducted compression tests to attempt to determine the required force, but only old
baobab seeds were used, which proved to be much harder and drier than fresh seeds would
presumably be. Still, if the prototype fails to work with fresh seeds, refinements may be needed
to enhance power generated by the hand crank.
        One suggested way to increase power is to implement gears to the hand crank. Adding
gears to the hand crank will increase the generated torque thus increase the efficiency of the
screw press. The main topic that coincides with this discussion is the potential use of bicycle
gears. From past visits to Africa and along with past research, it has been concluded that
bicycles are a very popular form of transportation in Morocco. If the future Baobab team could
somehow find a way to incorporate these gears into the design, untold improvements could be
made. As an extra plus the Moroccans prior experience with these parts would create an easier
transition into using and repairing the Baobab machine.
        If the bicycle gears are not sufficient enough for the hand cranking device, research could
be conducted on the local economy of Morocco and how difficult it would be to locate specific
types of gears. Cost should also play an important role in this research, because the cost
efficiency of the device should not be overlooked. Also, in order to reduce the cost of the screw
press, affordable substitutes could be designed to replace parts that are more sensitive to
damage such as the bars, rings, and hand crank. Again, research should be conducted to look
into the availability of different options and materials.

8. CONCLUSION

        Although the project cannot be declared a success until the screw has been obtained
and the prototype assembled, this team has made significant progress in the creation of a seed
oil extractor. A feasible design has been developed, and the initial prototype is on its way to
completion. After this has been achieved, testing can begin to determine its effectiveness, and
to decide what aspects of the design, if any, require improvement. The results of these tests will
be a critical step in the development of a final design, an endeavor that the PSU Baobab Initiative
will continue in semesters to come.

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APPENDIX

                                       Work Cited

Baumann, Willi. "Fly Press." Google Books. Web. 2 Feb. 2012.
    .

Rockholt, Rocky. "Coin Press." Google Books. 10 Jan. 2006. Web. 2 Feb. 2012.
    .

Woodford, Chris. "Gears." How Gears Work: A Simple Introduction. Web. 12 Mar. 2012.
    .

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