The document summarizes the design and testing of an oil expeller machine. It describes the key components of the machine including the screw shaft, barrel, choke, and liner bars. It discusses the fabrication process and testing, finding that the new design increased efficiency by 50% by allowing continuous cake flow for two passes compared to one pass for the old design. Areas for further improvement are identified as better positioning of the liner bar gaps and increasing the exposed bar area. The machine is suitable for small scale oil extraction in villages or research applications.

1. TEAM MEMBERS:
PRACHURYA SARMA
POORNA CHANDRA PRAKASH M. N
ABHISHEK KUMAR SINGH
HARSHITH.M
PROJECT GUIDE
T.C.Narendra Babu

2. The Oil Expeller is a screw type machine, which presses oil seeds
through a caged barrel-like cavity. Raw materials enter one side of the
press and waste products exit the other side. The machine uses friction
and continuous pressure from the screw drives to move and compress
the seed material. The oil seeps through small openings that do not
allow seed fiber solids to pass through. Afterward, the pressed seeds are
formed into a hardened cake, which is removed from the machine.
Expeller pressing (also called oil pressing) is a mechanical method for
extracting oil from raw materials. The raw materials are squeezed under
high pressure in a single step. When used for the extraction of food oils,
typical raw materials are nuts, seeds and algae, which are supplied to
the press in a continuous feed.

3.  Oil expeller is a mechanical equipment to
extract the oil from seeds the principle
behind this equipment is the friction between
the cylinder cage and worm shaft assembled
inside the cylinder.
 The seeds are feed through the hopper
which connects to cylinder and worm shaft
assembly, as soon as the seeds reach the
rotating assembly it gets feeded to crushed
and oil is extracted.

4.  Screw Shaft
 Barrel
 Choke

5.  The worm shaft conveys the material inside
the barrel and compresses the material
against a choke. The worm shaft is a large
screw, hence the name screw press. As the
worm rotates the seeds move forward
between the worm teeth. As they move
forward they are also rubbed against the
barrel walls.

6.  Straight Screw

7. The root diameter of the shaft increase to facilitate increase in
pressure as the seeds move forward. This also compensates for the
decrease in volume of the seed as they are compresses and as oil is
lost

8.  As there is a reduction in volume as the seeds
are compressed and oil is expelled, the mass
flow rate has to be reduced so that the
decrease in pressure due to reduction in
volume is compensated.

9. Tapered Root Diameter
Variable Pitch
Tapered Diameter and Variable Pitch

10.  Choke is installed at the discharged end. This
device has the function of operating pressure by
changing the width of the annular space through
which cake must pass. It is possible to adjust the
choke by a hand-wheel on the opposite end of the
screw. We are using a conical type of choke
mechanism.

11.  Nozzle Type
Seeds continue to accumulate at the end of the screw until the
maximum pressure has been reached. During compression, oil part
of the seeds leaks from the filter and the left cake starts to extrude
out from the nozzle, at the end of the screw.

12.  Conical Type
 In this type the cake is pushed over the conical choke. The
maximum pressure and the cake thickness can be changed by
adjusting axial displacement of the screw shaft forward and
backward in order to achieve the required pressure.

13.  Drilled Holes
In this system holes are made on the barrel so that oil flows out of
these holes. The main advantage of this system is no extra parts for
oil drainage system is required. However the oil drainage openings
in this system are not adjustable.

14.  Lining Bars with Spacers

15.  This kind of liquid drainage system is generally used for the
substances which do not require high pressure. Since the
fiber is a deformable material, high pressures would result in
expansion of the fiber.

16. Cylinder-Hole Press
• Drilled holes oil drain system.
• Nozzle type choke system.

17. Strainer Press
• Lining Bar Oil Draining System
• Conical Type Choke

18. Speed
Higher screw speed means more throughput and
higher residual oil content in the press cake since
less time is available for the oil to drain from the
solids.
Restriction size
When the restriction size is reduced the pressure
required to overcome the restriction increases. A
resulting decrease in oil content causes increased
viscosity of the paste and further pressure
rise.

19. Moisture content
• Moisture works as heat transfer medium. So the total heat
generated during pressing will be fully transferred to the
individual fat globules, which results in breakdown of the
emulsion form of the fat and helps in releasing more oil
droplets.
Temperature
• The friction inside the barrel generates heat which is passed
on to the oil. Increase in temperature of oil leads to higher
phosphor content. High phosphor content is an undesirable
fuel property as it can cause deposits and clogging in
engines.

20.  Strainer type expellor, i.e bars are used.
 The screw is of tapered shaft type.
 The pitch is 20mm and is constant.
 The root diameter of the shaft increases from 16
mm at the delivery point to 26 mm at the end of
the screw.
 The choke used is of conical type.
 The power system availble is a 1 phase 1hp
electrical motor with a speed of 1420rpm with
gear box and coupling arrangement. The speed
is reduced to 105 rpm in the gear assembly.

22.  Deformation of Shaft
 In the old model the liner bars have no gap
for oil flow, instead slots have been cut close
to the delivery side of the worm. That is the
oil has to travel back to the delivery side once
it has been extracted to flow out of the
barrel. This flow of oil is resisted by incoming
fresh seeds.

23.  The bars are ground near the center, so that
the oil can escape through the bars.
Old Liner Bar Arrangement
New Liner Bar Arrangement

24. Choke
The taper angle of the choke is reduced. This facilitates easy
flow of cake over the cake. The old choke had larger taper
angle and it was difficult for the cake to flow between the
choke and barrel. Also the choke is extended towards the rear
in the shape of a bolt head so that it is easier to adjust the
area for the cake to pass through.

25. Parts have been fabricated such that the
maintenance and handling is easy. Earlier the
bar holder and bearing housing had full body
thread, and hence it was very difficult to
dissemble the machine. So we have made
step in these parts so that its easier to loosen
them and the threads will not be damaged
too

27.  Solid steel rods of diameter 40mm and 90mm
each of length 35 mm were used.
 Material selected was Stainless Steel 202 as it
is hard and economical. The entire fabrication
was done in our college machine shop.

28. Face Turning
 The end surfaces were flattened and rod was
reduced to the exact required length by face
turning operation using a High Cut Carbide Tip
Tool.

29. Drilling
 Hole of 40 mm was drilled using drilling tool throughout the
rod. First a 20mm drill bit was used. Once the barrel was
drilled with 20mm throughout a 40 mm drill tool was used.
The feeding hole on the barrel was also made using the
drilling tool.

30. Boring
The different inner diameters within the barrel was
obtained by boring with boring tool. The barel was step
turned to create slots to hold the lining bars.

31. End Milling
 The slots that expose the bars were made by end milling
operation using an end milling tool. The hole for feed over
which the hopper is placed was finished using the end milling
tool.

32. Thread Cutting
 The worm shaft was made by the thread cutting operation.
The pitch of the thread was 20mm. The root diameter of the
worm increases from 16mm at the feed point to 26 mm at the
end. The part which holds the lining bars and the bearing
housing were also threaded.

33. Taperturning
 The choke was made by taperturning operation. The part
which is used to hold the lining bars tightly was also
taperturned on the inner side.
Tapping
 The end of the wormshaft and the choke was first drilled and
then tapped.
Coolants
 A soluble coolant was used for all the operations except
cutting, where water was used.

34.  High Cut Carbide Tip Tool
 End Milling Tool 20mm
 Boring Tool
 Drill Bits 20mm & 40mm
 Tapping Tools

35.  Karanjia seeds were used.
 Oil started oozing as the seeds reached the
end of the shaft
 Cake flow was continuous once the machine
started heating up
 Little amount of cake came out also between
the lining bars mixed with the oil
 The machine could expell oil from 6.5 to 7 kg
of seeds per hour

36.  The old machine could not run in the second
pass, whereas in the new machine the cake
flow is continuous even in the second flow.
 The through put of the old machine was
single pass of 6 kg per hour, but the new
machine can expel oil from two passes of 6.5
to 7 kg per hour, in terms of single pass it is
upto to 14 kg per hour.
 From the test it can be safely concluded that
there is upto 50% increase efficiency.

37. Cake coming out over the choke

38. Oil coming out through the liner bars and Slot made in Barrel

39. Cake after second pass

40.  The gap between the bars can be shifted away from the choke
as the pressure is very high near the choke region and this
pressure pushes a little amount of cake through the lining
bars.
 The gap between the lining bars and barrel wall has to be
increased and the area exposing the bars can also be
increased. By increasing the area exposing the bars, it is
easier to clean the cake that has escaped through the liners.

41.  As only two phase power supply is required,
it can be used in villages.
 As operating the machine doesn’t require
much previous experience, Self Help Groups
can adopt these machines to create self
employment opportunities
 Even bio diesel plants and universities, these
mini expellers can be used to extract oil in
small quantities from different seeds for
research purposes.

42. Sl No Particulars Cost(Rs)
1 Materials
SS202 45Ø 33mm
SS202 90 Ø 33mm
4300
2 MS Plates 350
3 Tools & Misc 1320
Total 5970

43.  1.)Singh and Bargale, 2000 "Development of a small capacity double
stage compression screw press for oil expression ", Journal of Food
Engineering Vol 43 75-82
 2.) Vadke V. S. and Sosulski F. W., 1988 "Mechanics of oil
expression from Canola", Journal of the American Oil Chemists'
Society, 65(7): 1169-1176.,
 3.) Faborode MO and Favier JF, 1996. "Identification and
significance of the oil-point in seed-oil expression." Journal of
Agricultural Engineering Research. 65(4):335-345.
 4.) Khan L.M. and Hanna M.A., 1983. "Expression of oil from
oilseeds. A review." Journal of Agricultural Engineering Research.,
28(6), 495-503.
 5.) Sukumaran C.R. and Singh B.P.N., 1989. "Compression of a bed
of rape seeds: the oil point". Journal of Agricultural Engineering
Research., 42(2), 77- 84.