Design, fabrication and characterisation of an electric powered yam pounding machine

Transcription

1 American Journal of Mechanical Engineering and Automation 2015; 22): Published online March 20, Design, fabrication and characterisation of an electric powered yam pounding machine Oweziem Bright Uchenna 1, Chinwuko Emmanuel Chuka 1, Ezeliora Chukwuemeka Daniel 1, Obaseki Efosa 2 1 Depertment of Industrial and Production Engineering, Nnamdi Azikiwe University Awka, Anambra State, Nigeria 2 Depertment of Mechanical Engineering, Nnamdi Azikiwe University Awka, Anambra State, Nigeria address chinwukoemmanuelc@yahoo.com C. E. Chuka), cezeliora@gmail.com E. C. Daniel) To cite this article Oweziem Bright Uchenna, Chinwuko Emmanuel Chuka, Ezeliora Chukwuemeka Daniel, Obaseki Efosa. Design, Fabrication and Characterisation of an Electric Powered Yam Pounding Machine. American Journal of Mechanical Engineering and Automation. Vol. 2, No. 2, 2015, pp Abstract This work focuses on the design of an electromechanical yam pounding machine. The machine consists of a shaft, electric motor, trough, propeller yam beater), pulleys and the frame with vents for adequate cooling of the machine during operation. Mild steel material and stainless steel sheet were used in the design based on its availability, strength, appearance, cost, and corrosion resistance. The maximum volume of yam pounded was gotten to be while a power requirement of 1hp was needed to drive the machine.however in this design, improvement was made on the overheating of the electric motor during operation by creating vents for adequate cooling, improvement on the size making it more portable than the existing ones and the use of dampers to minimize vibration with better reliability and working efficiency. From experiment carried out in using the machine to pound three different species of yam, it was observed that irrespective of the improvement done on reducing overheating during pound, it pounds in less time compared to the already existing ones. Keywords Design, Fabrication, Moment, Beater, Belt Pulley, Machine, Tension, Yam 1. Background of the Study Yam belongs to the class of carbohydrate type of food and had been one of the oldest recipes known to man. It has been a major food crop in many of the African/ Caribbean s countries such as Ghana, Ethiopia, Benin Republic and Nigeria in particular. Also, in some other parts of the world a Brazil, India, Oceania and Latin America; yam is a major source of food. The word yam was derived from the Wolof word nyam which is a Portuguese name meaning to taste. Also, in other African language, it can mean to eat e.g in Hausa nyam Mignouna et al, 2003). This perennial herbaceous crop is of different species such as the white yam Dioscorea. rotundata), yellow yam Dioscoreacayenensis), water yam Dioscoreaalata) and trifoliate yam Dioscorea. dumetorum) Amusaet al., 2003). The fruit of yam consist of a membranaceous, three-wing capsule. The yam family is mostly of the weak-stemmed vines with large, underground food storage organs-tuber-rhizomes. Yam has found its use in the preparation of steroid hormones by the syntax synthesis of cortisone from yam extract. Also, its lower glycemic index than potatoes products kay, 1987) accounts for its more sustainable energy and better protection against obesity and diabetes Walsh, 2003). According to the food information Network in 2008 it was estimated that the world production of yam in 1993 was at 28.1 million tons in which 96% of this estimate was from the West Africa tropical regions and 71% from Nigeria. This figure was later reviewed in 1998 accounting for about 72.4% of the world total production of 29.6million tonnes. Also, according to the Federal Office of Statistics, Nigeria is the world s largest producer of yams having the water yam Dioscoreaalarta) and the yellow yam Dioscorearotundata)as her most cultivated species of yam. Yam being one of the most sumptuous meals can be prepared in diverse ways. While the Yoruba tribe may prefer it dried, milled and then made into a slightly solid paste called Amala the Igbos would prefer cutting the tuber into smaller blocks or bits, boiled and eaten in other to avoid the

2 27 Oweziem Bright Uchenna et al.: Design, Fabrication and Characterisation of an Electric Powered Yam Pounding Machine tedious nature of pounding the boiled yam which results to bond formation like the Nigeria locally prepared fufu Akissoe et al, 2003). However, the process of meshing or beating something into pulp or powder with repeated heavy blows is known as pounding. Yam has remained one of the most highly regarded food products in West Africa and particularly Nigeria as virtually all her ethnic groups feed on it; hence its close integration into socio-cultural, economic and religious aspect of life such as marriage where some tubers of yam are presented to the bride family in accordance to the customs of the people Odior et al, 2012). Also, there is the new yam festival which marks the harvest and eating of the newly harvested yams and are also used as sacrificial and appreciation items. However, the background of this study originated from the desire of a Nigerian family of four who spent majority of his career life in the United Kingdom Bristol, England) in the medical field who came back home and needed to adapt to his home culture which he found pounded yam very sumptuous meal but the rigorous processes involved in the traditional method which he also observed to be unhygienic and the noisy effect of the process due to the number of strokes during pounding to be uncalled for Osueke, 2010). 2. Objective of the Study The objectives of the study were 1 To design and develop a portable electromechanical device which with rotary motion of the beaters perform the pounding operation which will be more efficient, less time consuming with less human effort and of a greater hygienic processing. 2 To make the beaters detachable for easy maintenance. 3. Literature Review of the Study Pounding has been an integral part of majority of the Africa people particularly Nigeria where virtually all the ethnic group have one or more item to pound before use. The ancient and traditional method of pounding is carried out with the use of the wooden mortar and pestle. The wooden mortar has a concave base with a cup-like hole in it for housing the items to be pounded, the pestle also, in a wooden long single or double edged smooth cylindrical base dumbbell shaped) used for the pounding. At present there exists different makes of yam pounding machine. One type cooks and pounds while another pounds only. The problem associated with them is that they are expensive to operate and acquire. Herbert and Kenwood mixing machines were in 1975 introduced into the market for use this however, gave rise to the conception and development of the yam pounding machine. The Herbert and Kenwood mixers were not originally designed for yam but gradually faded away due to its inefficiency in operation such as longer time in meshing operation and overheating of the machine which had to be stopped intermittently for cooling and the non-homogeneity in bond formation after meshing. Hence, the above argument ascertains that both the Herbert and Kenwood mixers were not originally designed for yam pounding but potatoes meshing as their mode of operation is similar. Also, these mixers have the following deficiencies on the pounded yam; i Hardness of the yam after pounding ii Presence of much un-pounded yam seedlings. iii Not compatible enough In 1980, some final year students of Obafemi Awolowo University took up the challenge to research and develop a yam pounding machine having studied the problems of the Harbert and Kenwood meshing machine. To their credit a design blue print was made and sent to Japan, and the first ever yam pounding machine was then fabricated and imported into the country but this machine was faced with the problem of its high cost, making it affordable to only the rich. However, some of these above mentioned deficiencies were improved on by Odior in 2008 where he designed another pounding machine capable of producing a better homogeneous bond yam. In his design, only the pounding chamber was considered having two beaters with curved blades. Though this design looks good but the machine was observed to operate at a very high speed and was not adequately ventilated resulting to the electric motor overheating hence having low durability which was also a part of the problems of the Herbert and Kenwood mixers irrespective of the fact that they were designed for the potatoes meshing operation and has no adjustable electric motor base for proper tensioning. After a period of two years, Osueke in 2010 improved on the design made by Odior by incorporating a steaming chamber inside the pounding machine. This design of his in 2010 consists of mainly two chambers which were made of stainless steel and shafts. One of the chambers is used for cooking while the other chamber is used for the pounding. Though this design tends to be good as two operations were being accomplished with the machine but the problem of overheating continues and even higher than those of Herbert and Kenwood mixer irrespective of the number of vents introduced for cooling. However, this machine gives a better quality product at a higher speed but the cost of production or manufacturing was high hence its high cost of purchase. Also, a particular species of yam was known to pound well with this machine that is the water yam. Likewise the bulky nature of the machine makes its portability a mirage. Hence, in this design, the above mentioned challenges were been eliminated by eliminating the cooking chamber thereby overcoming the issue of overheating, operating the machine at a moderate speed and as a result increases the life span or durability of the machine. Also, improvement in the quantity and quality of yam pounded in less time which was one of the major problems of the Herbert and Kenwood mixers. Hence, these improvements make the machine suitable for commercial and domestic use. Also, to put a margin between the advantages and disadvantages of the machine usage, the protective electric motor device fuse)

3 American Journal of Mechanical Engineering and Automation 2015; 22): considering the fluctuating and inconsistent power supply thereby increasing its reliability. Finally, the simplicity in its manufacturability is an added advantage as it tends to provide job for the young and unemployed mechanical engineers/ technologists as the raw materials are readily and locally available. This will to a great extent reduce unemployment. 4. Design Analysis, Construction and Material Selection In machine design and construction, there are numerous considerations that are being made as well as assumptions. These considerations are in area of the choice of design, material selection with respect to its properties, load to be overcome by the machine, safety of operation, cost of construction friction resistance and lubrication, etc. However, in this design, the machine fabrication, its operation, material selection were carefully done bearing in mind the operation of the machine. Also, the conditions considered in this regards were the tendency of the chosen material to fracture under fatigue, resistance to wear during operation corrosion when in contact with moisture and ability to conduct heat to the atmosphere to avoid overheating as a result, cools the machine while in operation, material toughness and strength were not left out. 5. Machine Components These are unit components of the machine that are assembled together to form the entire machine. The machine components include; the machine structural frame, trough, blade or impeller, pulleys, shaft and the electric motor which was selected. 6. Material Selection Material selection is one of the most important aspects that demand the understanding of each of the functional requirements for the individual machine components as they are ever-increasing varieties of materials presently available and the development of new materials with unique properties and applications Budynas, et al, 2008). Hence, the difficulty in materials is as a result of these varieties of materials in the engineering field coupled with the complex relationships between the selection parameter such as its functionality. If the selection process is done haphazardly, the risk of overlooking a possible attractive alternate material may occur. To avoid this there is the need for the analysis of the material performance requirement. However, the material performance requirement was considered in the following areas Kalpakjian et al, 2006). 7. Design Factor This refers to some characteristics which affects or influence the design of the machine or perhaps some of the components. However, out of the numerous factors that affected the design, only one or few will turn out to be the major factors and the minors ignored as they would have little or no effect in the design. These factors or characteristics are; i Thermal conductivity of the material ii Strength of the materials used iii Overall weight of the machine in order to achieve its portability and machine size iv Ease of maintenance v Noise and vibration vi Resistance to corrosion attack vii Finishing 8. Design Analysis of the Components Osueke 2010, experimented and determined the density of yam to be1250 / and1950 / for the before and after boiling respectively. This figure have been generally accepted and used in various works such as that of Odior et al, 2012) Analysis of Production capacity of a yam flour for producing firm using a mathematical model. 9. Determination of the Crushing Force and Power Requirement The crushing force is the force required to masticate the yam to fine desired texture. Let the crushing pressure be denoted by Then Where Crushing Pressure = h 1) = = 1950 / ss =!""# $ # % = 9.81/ h =h h h # = 0.1 Pressure = = */ Then, the force acting on the edge of the beater in contact with the yam is given by Where, * + =!, 2) * + = -#" " h $# " # h # " ".h h = * + =28.504*

4 29 Oweziem Bright Uchenna et al.: Design, Fabrication and Characterisation of an Electric Powered Yam Pounding Machine Hence the turning effect of the beater better performance. 0#1$ 0 =#" " h # # h "# 2% 0 = * 0 = * + 3) Then the power requirement to operate the machine Power P) = Torque 0, ) Angular Speed.) Where 0,. 4) For a better performance an optimal speed of 450rpm was chosen and a factor of safety 3.0 was also chosen for reliability purpose. This implies that Hence considering the chosen factor of safety, the minimum power requirement for the design Recall that, 1hosepower = 746watts So, since Then an electric motor of 1hp with speed 1440rpm was chosen 10. Belt Design The essential characteristic of the belt drive is to transmit power in the form of rotational motion to the beater shaft. The tension on the two sides of the belt is different, that is one side is slack and the other side tight. Hence, this design was determine by the length of belt, wrap angles, belt tension and proper belt selection to transmit the required power. The center to center distance of both pulleys is determined by the formula 5) 8 89 : ; < : = > 6) 8 8? 371 < A However, a center distance of 300mm was then chosen for Figure 1. Length of Belt Recall that, 71mm = 0.071mm 224mm = 0.224mm 8 300mm = 0.3mm Then, the length of belt is given by the mathematical expression, L = 3B : ; C : = D = <28 < B: ; C : = D E 3B6.6FG 6.HD C B6.D CB6.6FG C6.HDE = = 1.136m = 1136mm HB6.D Hence, A belt was selected for the pulley 11. Maximum Power Transmitted by Belt This is given by the relation 7) B0 G I 0 D% 8) Power of Electric Motor = 746watts 0 G Tension on tight side 0 Tension on slack side % Belt speed in m/s Hence, recall that: Then V = 5.35m/s B0 G I 0 D% 746B0 G I 0 D G 0 < G 0 < ) So solving equation 8) and equation 9) simultaneously, 0 G I ) 0 G 0 < )

5 American Journal of Mechanical Engineering and Automation 2015; 22): Then, Substituting In equation 16a) 12. Shaft Design I * 0 68* 0 G I B68DI G * In this design, the important factor is to determine the minimum shaft diameter, which will be able to withstand the loads it will be subjected to. These loads include; the bending load, the torsion load and the axial pulley weight. Hence, the minimum shaft diameter can be determined using the formula below Where, A = Effective area of the beater B = Width of beater h = Height of beater H = Total length of beater Then A = BH + bh b = BXYZD = ) ) = 0.027m 2 A = 0.027m 2 Volume of space occupied by the beater inside the trough [! ) U JK G5 NOBBP 3L Q D < BP R Q R D DST M 12) Where Minimum diameter of shaft P Maximum bending stress P R Maximum bending stress Q Fatigue factor for bending moment Q R Fatigue factor for torsional moment But for the torsional torque P R Where, 0 V N N P R B 0 V I 0 DW 13) W Radius of the beater pulley = 112mm = 0.112m Then P R B I66.18D0.112 = 15.20Nm = Nmm 13. Beater Design Hence, the effective area of the beater is calculated thus; A = BH + bh 14) Figure 2. Diagram of the beater 14. Tangential Force on the Beater From the relationship of torque and force, the tangential can be determined for outer and inner rods. For the outer beater rods, Torque, T = outer torque on the shaft Where 0 \.]]^ 4 P = Motor power in watts = 745.7w N b = speed of shaft in rpm = rpm Torque, 0 But \.]] FH5 H]5.H = 15.61Nm Diameter of Beater, Torque, T = Force F) Distance r) = -#" :+V_,R,` 16) 17)

6 31 Oweziem Bright Uchenna et al.: Design, Fabrication and Characterisation of an Electric Powered Yam Pounding Machine D = 220mm =0.22m Therefore, Tangential force on beater, - = a : 18) beater which is due to pressure. Hence, #$# = = N/m 2 But the force due to this pressure is Force, - = = N Then for the intermediate beater rod - 6] = N/m 15. Resisting Force on the Beater Considering the cylindrical trough in which the beater rotates, F p = Pressure area of beater 20) = = N 16. Machine Pounding Capacity The maximum machine pounding capacity is determined as follows, Maximum Volume of Yam Pounded [ _ [ _ [ R I [ Where, [ _ P 8$ 2$ " 2 " [ R [$ #$ [ [$ ""$2 # So, I Maximum volume of yam pounded = Bearing Design and Selection Figure 3. Diagram of the Trough Weighing the yam Mass m = 2.52Kg Then Volume of the cylinder trough [ 7# =.GH 6.]E 6. H = m 3 = mm 3 The density of boiled yam in Density,, _Vcc defg_, Density = kg/m 3 19) During operation, there is a force equal at all points of the The single row deep groove ball bearing was chosen because of its high load carrying capacity and suitability for high running speed. Considering the diameter of the shaft which is 30mm, a bearing of bore 30mm was then used for this calculation. The specific static load rating or capacity C o Arvid, 1945) Where, h e G ] e i "j k h e 2"" " # # " 2 " 10* e "# 2 2 # = 12.3 k # j *# " " 0 *$# #. # 1 i $# 2# #. #% 6 q _Vr 8$ # 21) e l mno : p E 22)

7 American Journal of Mechanical Engineering and Automation 2015; 22): And the above data Budynas et al, 2008) the ball diameter can be calculated t u ] k = s9 > 23) v u + wxecy = JK "0 T Then the maximum bearing load in equation 23) q _Vr e k = N e q _Vr k A bearing of 6206, which is of an inner diameter of 30mm and outer diameter of 62mm, then was chosen. The bearing number interpreted as 200 means a light bearing of bore that is inner diameter of 06 5 = 30mm. Also, in the selection of this bearing, the radial load of which the bearing can carry was considered. However, for the ball lubrication, grease should be used at low and medium speed when the temperature is not over 20ºC while oil should be used at higher speed. Hence, in this design, grease is the most satisfactory lubricant. 18. Fabrication, Testing and Characterization The process used in the construction of the components is discussed below. However, some of the parts fabrication had earlier been discussed in the previous chapter. 19. Fabrication Process of the Machine Parts The top plate, brackets for mounting the electric motor was welded and dampers attached to reduce vibration. These frames in which the electric motor and the trough are mounted are made of the mild steel. The first process of the fabrication of this machine was making the working diagram which serves as a guide in the course of its manufacturing. Secondly, the selection of materials for the work was then considered. This was done with respect to the availability of the raw material locally and the cost implication was also considered. Next, marking and cutting of the materials. This was done with the aid of the meter rule and inscriber for marking and the work piece held on the vice while the cutting was carried out. 20. Assembling of Parts The frame of the machine made of mild steel was welded which remains one of the most versatile and effective means of fabrication and individual components assembly into larger module; hence, it is a fabrication process that joins materials such as metals, thermoplastics by way of causing coalescence which is often done by melting the work piece and a filler material to form a pool of molten metal the welded puddle) that cools to become strong joint with pressure sometimes used in conjunction with heat or by itself produces the weld. This was done by electrical arc welding and the electrode. This welded steel forms the rectangular frame for coupling the other parts of the machine such as the electric motor and the trough for pounding. Also, other mode of assembling used here was riveting and screws which were fastened to the hold the 2mm thin sheet. However, the entire structure was filed and polished with abrasive paper to obtain a perfect finish and was painted with spraying machine and was then allowed to dry in a dust free environment. A B

8 33 Oweziem Bright Uchenna et al.: Design, Fabrication and Characterisation of an Electric Powered Yam Pounding Machine C Figure 4. AutoCAD Components Diagram Figure 5. 3-DAutocad Diagram of the Machine and Beater 21. Bill of Engineering Material Components and Evaluation Considering the fact that the total cost of producing this machine is less than the market price, which was discovered from market survey carried out to be within the range of N35,000 N40,000. It is therefore obvious that this design is quite economical. 22. Result and Discussion Three species of cooked yams where tested with the machine by operating it to pound the cooked yams and it was

9 American Journal of Mechanical Engineering and Automation 2015; 22): observed that the white yam Dioscorea. rotundata), took a maximum time of two minutes thirty seconds, the yellow yam Dioscoreacayenensis), took a maximum time of three minutes and the water yam Dioscoreaalata) took a maximum time of two minutes. However, only the water yam was semi-starchy while the white and the yellow yam were starch. The machine was also, observed while in operation and it was found that the resistance of the electric motor to vibrations and its performance were satisfactory, pointing to the fact that a greater percentage of the vibrations set up during the pounding process are absorbed by the damper on the electric motor seating and fan belt. Table 1. Standardized Bought materials Material Unit Price Total S/N Description Quantity Components N) N) 1. Electric Motor 1hp 1 8,500 8, Bolts and Nuts M Ball Bearing Belt V-Belt A Electrode Screws Cap Screw S/N Material Components Metal Rod for Shaft Angle Bar for Frame Stainless Steel Sheet 4. Flat Mild Pan) Table 2. Machined Components Description Quantity Unit Price N) Total N) Ø 30mm ,000 3, /50FT 1 3,700 3,700 2mm Thickness 1 2,200 2, Miscellaneous 2,500 Total Productivity Considering the traditional way of yam pounding, time and the manpower required in carrying out the operation, if it takes a minimum of 1-3hours to pound about 20kg of yam manually coupled with its unhygienic mode of operation, it will take about 15minutes to pound the quantity of yam with greater output quality. Hence the general productivity per hour for the machine can be calculated thus, In 15minutes, 20kg of yam was pounded 56 6 Therefore, in 1 hour 60minutes), = 80kg Hence, output of 80kg of pounded yam per hour indicates that the machine is of high productivity, efficient and also saves time. 24. Conclusion Although they can be other possible challenges which this machine can solve such as in the pounding of fufu, however, G] it is gratifying that to know that it has been proven to perform its function satisfactorily. It is pertinent to add here that some of the materials used for this fabrication may not be adjudged as the best in the market but were selected based on the constraint of cost. This is in reasonable cost while still ensuring that the materials used perform their function satisfactorily. Also, the volume of yam pounded at a time is mm 3 ) which is approximately enough to feed two or more people. Finally, it is expected that with the low cost of this machine manufacturing that every home can comfortably proper pounded yam in a hygienic way even as more improvements would be definitely made on it as researches and the engineers are out to make life more comfortable to man in all area most especially concerning this he eats. Recommendation It is recommended that all homes should procure at least a pound machine to enable them prepare a good and hygienic pounded yam thereby saving them from the strenuous and the traditional method of pounding yam. Also, the young graduate mechanical engineers should be made to undergo compulsory training on technological skill acquisition such as the design and fabrication of a machine such as this to enable them be self-employed and also, employer of labour thereby reducing the search for white-collar job References [1] Walsh S 2003). Plant Based Nutrition and Health. ISBN New York, USA. pp [2] Muller, K and Ennis D.M 1979, Rotatable designs in product development. Food Technology, Vol. 337): 5-5 [3] Gupta J.K and KhurmiR.S2004). Publishing HousePvt). Ltd, New Delhi. pp , [4] Habart& Kenwood, 2007). Power Splitters, Patent & Design Journal, No. 6159, June 2007, pp [5] Mignouna, H. D., Abang, M. M. and Asiedu, R. 2003). Harnessing modern biotechnology for tropical tuber crop improvement: Yam Dioscorea spp.) molecular breeding. Available online accessed on the 5 th of August [6] Budynas, Nisbett 2008) Shigley s Mechanical Engineering Design, Mcgraw-hill companies 8 th edition pp15,351 [7] Food Information Network, 2008). Wageningen University, the Netherlands. [8] Odior A.O, Orsarh E.S 2008), Design and Construction of a Yam Pounding Machine, International Journal of Nature and Applied Sciences, 43): pp [9] Odior A.O, Oyawale F.A 2012) Analysis of Production capacity of a yam flour producing firm using a mathematical model, ARPN Journal of Engineering and applied science. pp [10] Osueke C.O,2010). Design and Construction of a Yam Pounding Machine, Avaliable online blogsite) accessed on the 12 th of September 2012.

10 35 Oweziem Bright Uchenna et al.: Design, Fabrication and Characterisation of an Electric Powered Yam Pounding Machine [11] Akissoe, N., D.J. Hounhouigan, C. Mestres and M. Nago, How blanching and drying affect the colour and functional characteristics of yam DioscoreaCayenensis- Rotundata) flour. Food Chem., 82: [12] Federal Office of Statistics, Nigeria Trade Summary. Federal office of Statistics, Lagos, Nigeria. [13] Kalpakjian, S., Schmid, S. 2006). Manufacturing Engineering and Technology, Pearson Education Inc., Upper Saddle River, New Jersey. pp [14] Avid, P. 1945). Ball and Roller bearing Engineering, S.H Burbank and Co., Incorporated Philadelphia. Pp78-86