Apalm nut cracking machine with an efficiency of 74.2 percent, a throughputcapacity of 75.6 kg/hr has been successfully and economically designed anddeveloped. The machine was developed using locally sourced materials. Also,Maximum loading of the hopper which is about 10.8 kg and 0.02m3 involume will be cracked in about 9 minutes.
The average amount of palm nutscracked per day is about 1872kg by the cracking machine, it takes a normalfarmer about 144 kg per day. Therefore the cracking machine using locallysourced materials will help increase productivity and efficiency in the palmnut cracking process in the rural areas.CONCLUSION Theaverage amount of palm nuts cracked per day is about 1872kg by the crackingmachine, it takes a normal farmer about 144 kg per day.Basedon the average amount of cracked palm nuts supplied into the machine, it can besaid that the average efficiency of the machine is about 74.2%.The palm kernelnut cracking machine has an average efficiency of about 74.2 %. (25)Byutilising Gbabo et al.
(2013) equation for efficiency which was adopted for thedehulling efficiency for the Moringa dehulling machine by Ikubanni et al.(2017), the cracking efficiency for the palm nut cracker was derived usingequation (25).Therefore10.8kg will take 514secs which is about 9mins.
Since1kg of palm nut takes 47.58sec,Thehopper has the shape of a frustum of a pyramid. The total mass of the palm nutsthat can be accommodated in the hopper is 10.
8kg.=(0.021kg/sec) × 3600 sec = 75.6kg nuts/ hourTherefore,throughput capacity (nuts/hour) = shelling rate × 1hour (24)Theexperiment in evaluating the machine shows that 1kg of palm kernel nut cracksat an average time of 47.58 seconds which implies that in 1 second the machinewill crack 0.
021kg of palm kernel. Mass of palm kernel Nuts (kg) Cracking time taken (s) Mass of Un-cracked nuts (kg) Mass of cracked nuts Mass of partially cracked Nuts (kg) 1 46.13 0.3 0.64 0.
06 1 50.02 0.2 0.
76 0.04 1 48.26 0.27 0.66 0.07 1 44.21 0.
18 0.8 0.02 1 49.27 0.1 0.85 0.05 Average 47.
578 0.21 0.742 0.
048 Table1:Performance tests on the developed palm kernelnuts cracking machineTable 1 showsthe performance evaluation results for the developed palm kernel nuts crackingmachine, with speed of 1400 rpm. The experimental tests show that at the samespeed, 1kg of palm kernel nut will crack at an average time of 47.58 seconds.The average mass for the un-cracked palm nuts, cracked palm nuts and partiallycracked palm nuts were 0.21 kg, 0.742 kg and 0.048 kg, respectively.RESULTS AND DISCUSSIONFig.
3: Pictorialview of the machine Fig. 2:Isometric View of the machine Part No. Part Name 1 Hopper 2 Drum 3 Shaft 4 Collection tray 5 Electric motor stand 6 Frame/Stand 7 Drum handle Fig.
1:Orthographic Projection of the machine Thedriving unit consist of an electric motor and a pulley. The electric motor israted one horse power (1hp), with frequency of 50 Hz and revolves at 1400 rpm. Thepulley is of diameter of 80 mm connected to the driven pulley by a belt 480 mmlong, 12 mm wide and 9 mm thick.The Driving UnitThe hammers are made of mild steelplates of 50 mm width, 130 mm long and 8 mm thick. Each hammer has twosections; one which is attached permanently to the shaft, and another attachedto the initial plate by a temporary joint.
The section attached to shaft has alength of 60 mm and is slotted at its centre to allow total change in length ofthe hammer. The section is 100 mm long, and is drilled 15 mm from the bottom toallow screws pass through (the same screws pass through the slot available onthe first section). The change in length is required in case of wear of the tipof the hammer as a result of hitting the nuts at very high speed. The hammersare placed in pairs horizontally along the length of the shaft and an angle of1200 separating the shafts on the circumference of the shaft.TheHammers Thedriven unit consist of the shaft to which six hammers are attached and apulley. The pulley has a diameter of 175 mm.
the shaft is made of mild steel,and has a diameter of 25 mm for a length of 50 mm at one end of the shaft, adiameter of 39 mm for a length of 150 mm (to which the hammers are attached) atthe centre, and a diameter of 25 mm at the other end of the shaft for a lengthof 100 mm.The Driven UnitThedrum is the cracking unit of the machine made of mild steel plate. It is madein the shape of a hollow cylinder with a diameter of 415 mm, has a height of200 mm, and the plates are 10 mm thick. The cylinder is covered on both sideswith a circular plate 420 mm diameter which has circular openings of 50 mmdiameter for shafts to pass through. Inside the drum is a portion of the shaftto which the hammers are attached.
The rotating action of the hammers, as aresult of the rotation of the shaft, cracks the palm nuts fed into the chamber.At the top of the drum is an opening 30 mm by 140 mm which opens up to thehopper. At the bottom also are series of openings through which cracked nutsfall out of the drum.The DrumThehopper is the feed-in unit of the machine. It has the shape of a hollow frustum,and is made of mild steel. It has a height of 300 mm, a length of 30 mm at thebottom and 300 mm at the top of two of its plates.
The other two plates have alength of 140 mm at the bottom and 300 mm at the top. The four plates aremarked and cut out from a metal sheet of 3 mm thick, welded together usingelectric arc welding. The hopper is placed vertically on a drum to allow thenuts fall under gravity.The HopperMachine Parts and Fabrication Angleof Lap = 419.67W Powertransmitted by the belt = 47.72 NTensionin slack side T2 = 0.4 x T1 = 0.4 x 119.
3 = 119.3NMaximumvalue of Tension in tight side T1 = 129.6 – Tc = 129.6 – 10.
3 =129.6N Maximumsafe belt tension = Max stress x cross sectional areaFromcalculation,, and WhereN1 = r.p.m of driving pulley; N2 = r.p.
m of driven pulley;d1 = diameter of driving pulley; d2 = diameter of drivenpulleyAlso,Where is angular velocity and N is speed of rotationin revolution per minute Assumemaximum stress in belt is 1200 kN/m2, and tension in slack side is40% of tension in tight side.Massper unit length of belt, m =0.3kg/m; Belt Length = 48cm = 0.48m; Belt Breadth=0.012m; Belt thickness = 9 x 103m;where is centripetal tension, is mass and is the speed.Centripetal Tension, Design for BeltsHowever,three (3) hammers were acting at a point; therefore, the point load wasdetermined to be .Usingthe above formula, the mass of a single hammer was calculated to be 0.628kg andthe weight was derived to be 6.
16 N. Densityof mild steel is 7850kg/m3, and Torqueproduced by electric motor, T=5.12N-mPowertransmitted, Therefore,an electric motor of one horse power (1hp), with speed of 1400 rpm and powerrating of 750W was chosen.
P=328.7WThe minimum power requirement, Mechanical PowerrequirementT= 3.537 NmWhereThetangential force, Where is the mass, is the radius of gyration, is the moment of inertia about x-axis, b and hare the width and height of the hammer, respectively. Momentof inertia about x-axis Toallow a gap of only 0.03mm between the hammer and the drum, a total hammerheight of 0.32 m is required.
where is the total height of the hammer. Radius of gyration of hammer,Shaft Requirement =14.869 m/secFor Dura Nuts,Hammer Requirement Where is the deformation energy and is given as0.
9012 dura nutsHence,Thereforer = 2, and F = 2PWhere and WhereP is the impact loads applied to kernels and r is the ratio of the stress underimpact to the direct stress or the deformation under impact to thecorresponding deformation. WhereF is the force or load applied and x is the distance travelled. Impactenergy on the cracking wall = Work required to deform a kernelKinetic energy of kernels = Impact energyof kernels on the cracking wallCracking RequirementDESIGN ANALYSIS The materials selectedfor the design and construction of the machine were majorly the stainless steeland the mild steel. The criteria ofselecting these materials are: (i) durability of the material, (ii) strength ofthe material, (iii) suitability of the material for cracking operation, (iv) availability of the material and (v)the cost of the material. In order to haveefficient design, various design considerations were put into place.
Thehopper, drum, the cracking mechanism parts (hammer), shaft and frame were frommild steel. The thickness of the mild steel used for the hammer is more thanthat used for the hopper. This is expected to be because the cracking of thepalm nuts require harder materials to crack the nuts and a designed speed ofrotation for the shaft. DesignConsideration and Material Selection for Production When the palm nuts arefed into the hopper, they descend into the cracking chamber by gravity, aidedby vibration agitated by the prime mover. The high rotating hammer impactsforce on the nuts suddenly; the nuts are then thrown towards the wall of thecracking drum. The nuts also impact energy on the wall of the cracking drum.
The sudden impact load of the hammer on the nuts lead to the breaking of thenuts and the shells are fragmented into smaller parts due to centrifugalaction. The kernel and the fragmented shells are force driven out of thecracking chamber to the collecting bowl at the outlet.The palm nut crackingmachine is made up of about five units viz: the feed-in unit called the hopper;the cracking unit called the drum; the driving unit consisting of an electricmotor, pulley and V-belt; the driven unit which consists of a rotating shaftthat bears the cracking hammers’ being driven by a V-belt connected to a primemover. The stand and the supporting frame is made of angle iron of gauge 50 mmby 50 mm by 6 mm. The hopper is made of mild steel of 3 mm thickness and has acapacity of 0.018 m3; and can accommodate palm nuts of about 10.
8 kgat its full capacity. The cracking drum is made of mild steel of 10 mm thick,the rotating shaft is supported at both ends on bearings and it is of length300 mm with a diameter of 25 mm for a length of 50 mm from one end and 25 mmdiameter for a length of 100 mm from the other end with 30 mm diameter for alength of 150 mm at the centre, where the hammers are attached. The hammers aremade of mild steel of 8 mm thick, 50 mm wide and 130 mm long. The electricmotor of the driving unit is rated 1hp with frequency of 50 Hz, speed of 1400rpm.
The pulley has a diameter of 80 mm which is connected to a V-belt oflength 480 mm, 12 mm wide and 9 mm thick. The pulley attached to the rotatingshaft has a diameter of 175 mm. MachineDescription and Working PrincipleIn the methodology forthis work, the design analysis of the palm nut cracking were done, materialselection for each component designed were determined, the design calculationsof the machine parts were done, operating description of the system wasdiscussed and the engineering drawings were shown. Electric motor serves as theprimary source of driving the machine so as to perform the required action ofcracking palm nuts.
MATERIALSAND METHODS Inorder to mechanise cracking of palm nuts, a palm nut cracking machine wasdeveloped in this work. Moreover, the performance evaluation of the developedmachine such as determination of the efficiency, throughput and processing ratewere done. The developed machine will help to reduce the laborious task andtime of cracking palm nut for other processes.Dueto the ever increasing demand for products derived from processed palm kernel,there is a need to improve on the traditional method of cracking throughmechanisation to ensure ready availability. The nut cracking is one of the mosttime consuming activities of the palm kernel processing, therefore theintroduction of a machine to crack and separate palm kernel from its shell at afaster rate will go a long way in speeding up the process, and helping to meetdemand.Ismailet al. (2015) developed and improvedpalm kernel shelling and sorting machine with a shelling and sorting efficiencyof 90%, and throughput of 59 kg/h. The whole kernel recovery was 70 percent.
Adejuyigbe et al. (2017) designed an improved palm kernel shelling and sortingmachine which can be used to crack various sizes of palm kernel with anincorporated sorting unit for separation. The efficiency of the machine wasdetermined to be 98% with 95 nuts per second as the processing rate. Acomparison was made with an existing palm kernel machine of 90% efficiency and87 nuts per second processing rate without separation.
A modified design ofpalm kernel cracker was done by Asibeluo and Abu (2015) in which a crackingrectangular channel was welded to acracking flywheel with a centralized hole through which every nut must passthrough and capable of making contact with every nut; hence cracking nearly allthe nuts. This design was incorporated with two different separators. Oyebanjiet al. (2013) performed the evaluation of two different palm kernel nut crackerdesigned. It was stated that thevertical centrifugal palm kernel cracker is more efficient than the centrifugalimpact approach palm kernel cracker considering their respective efficienciesof 71.3% and 50.
38%. Some other works on palm kernel cracking were done byJimoh and Olukunle (2013); Koya (2006) and many others.Crackingpalm nuts is a critical step that can affect the quality of kernel oil(Oyebanji et al., 2013). The manual(traditional) and mechanical (mechanized) method are the two commonly usedmethods for cracking. In traditional processing, the nuts from the oil palmfruits are cracked manually using a stone, or any other heavy and dense objectone at a time.
As a result of this, the processing altogether takes excess time.Moreover, this method is labour intensive, time consuming and cumbersome (Oke,2007). In cases where demand is high, a large labour force is required to meetup with such demand, which in turn increases the overall cost of the process asa result of an increase in the amount paid as wages to workers; therebyincreasing the selling price of its final products. In areas where a palm nutcracking machine exists, they are usually too expensive for local processors toafford, as most of the machines are imported due to the lack/short supply oflocally fabricated palm nut cracking machine.
Thedeveloped oil palm tree is typically single stemmed, around 20 m tall with astout trunk of around 75 cm in breadth, with an outside root framework. Theorganic products (fruit) take around 5-6 months to develop from the onset offertilization to development. The oilpalm organic product comprised of an external skin (exocarp), a mash (mesocarp)containing the palm oil in a stringy framework, a focal nut comprising of ashell (endocarp) and the bit which itself contains an oil (Udo et al. 2015).The preparation of the palm natural product to get the palm kernel begins withthe extraction of palm oil from the palm organic product, the division of thenuts from the fiber, drying the nuts, and afterward the popping of the nuts toacquire the kernel which can then be handled to get palm kernel oil (Ismailet al. 2015).
Palm kernel oil discovers application in cleanserproducing enterprises, oil preparing businesses, nourishment handling ventures,makeup enterprises and pharmaceutical ventures. Extraction of oil from palmkernel is such a critical part of palm kernel processing, and as the palm oilgeneration experiences a lot of mechanical improvement, the palm kernel oilcreation is still less motorized and this generation procedure really startwith the division of the fibre from the palm nuts from which kernel oil isdetermined. Consequently, separating the palm nut to get the kernel is anextremely significant part of kernel processing as the ability to crack openthe nut without causing harm to the kernel itself is important to limit waste, andthereby increasing productivity.Thepalm organic product (Elaeis guineensis) stands out amongst the most imperativewellsprings of oil for household and mechanical purposes in West Africa and thewhole world. As a drupe, it is comprised of three noteworthy layers: theexternal layer known as epicarp; a beefy mesocarp from which palm oil isremoved and a hard endocarp (shell) which constitutes the nut (Okokon et al., 2015).
The palm kernel is thepalatable seed of the oil palm organic product. The natural product yields twounmistakable oils: palm oil and palm kernel oil. The palm oil is gotten fromthe external piece of the natural product, while the palm kernel oil is gottenfrom the nut. The oil palm tree is an enduring plant. It is initially fromAfrica particularly the southern parts of Nigeria and Ghana (Ismail et al.
, 2015).INTRODUCTIONKey words: Cracking, Development,Evaluation, Machine, Palm nutPalm nut crackingmachine is a mechanical device developed for the cracking of palm nut insteadof the traditional method. The traditional method involves raising a smallstone on a larger stone or any hard surface to crack the nuts placed in betweenthem. This method is tedious, time consuming and has a low production rate. Thecracking machine is developed using mild steel metal of 1mm thickness for thehopper, angle iron of 1mm thickness for the stand, the cracking chamberconsists of a drum of 5mm thickness, the shaft of 39mm diameter, and thecracking hammers made of mild steel metal plate of 10mm thick.
The hopper has amaximum capacity of about 0.02 m3. The inlet to the cracking chamberis about 30mm wide. The machine is powered with electricity through an electricmotor of 1hp. The pulleys are 175mm and 80mm in diameter. The length of theshaft bearing the cracking hammer is 300mm with 39mm diameter. The machine is designedto operate at a power rating capacity of 420W.
The machine cracks 1kg of palmnuts 47.58 seconds and can crack 10.8 kg of palm nuts in 514 seconds. Theefficiency of the machine is averagely estimated to be 74.
2%. Thethroughput of the machine is determined to be75.6kg nuts/ hour. This mechanizedsystem of cracking is faster, less tedious with increased rate of productioncompared to traditional (manual) cracking method.ABSTRACT
