ERGONOMICAL EVALUATION OF SELECTED MANUALLY OPERATED COCONUT DEHUSKERS

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1 ERGONOMICAL EVALUATION OF SELECTED MANUALLY OPERATED COCONUT DEHUSKERS P. P. Pawase 2, R. R. Kadam 3 and K. G. Dhande 1 1 Associate Professor, Department of Farm Machinery and Power, College of Agricultural Engineering and Technology, Dapoli, Dist- Ratnagiri, Maharashtra 2 Graduate Student, College of Agricultural Engineering and Technology, Dapoli, Dist-Ratnagiri, Maharashtra 3 Graduate Student, College of Agricultural Engineering and Technology, Dapoli, Dist-Ratnagiri, Maharashtra ABSTRACT The ergonomical study of a folding type and non-folding type manually operated coconut dehuskers was carried out at College of Agricultural Engineering and Technology, Dapoli for its suitability to farmers on the basis of dehusking capacity, dehusking efficiency, damage percentage and ergonomical considerations like heart rate, oxygen consumption rate, energy cost of operation, acceptable work load, overall rating (ODR) and body part score (BPDS) during operation. Dehusking of coconut is drudgerous operation. To reduce drudgery in the dehusking operation, Dr. B. S. Konkan Krishi Vidyapeeth, Dapoli developed two types of coconut dehuskers, one is folding type and another is non-folding type manually operated dehusker. The performance of folding and non-folding type manually operated coconut dehusker was evaluated. The dehusking capacity and dehusking efficiency for folding and non type coconut dehusker were observed as 58 nuts/h and 93.7 % and 52 nuts/h and 93 % respectively. No damage to coconut shell dehusked were observed with both type. The average energy cost of operation of subjects while coconut dehusking with folding and non-folding type coconut dehuskers were 4.29 and 4.82 Kcal/min respectively. The average oxygen consumption rate as per cent VO2 max while operating folding and non-folding type coconut dehusker were and l/min respectively. The coconut dehusking operation with folding and nonfolding type coconut dehusker was within acceptable workload limit. The average HR value for subjects while coconut dehusking with folding and non- folding type coconut dehuskers were and bpm respectively which was less than limit of continuous performance (LCP). Copyright IJAER 2016, All right reserved Page 499

2 The mean value of overall rating of subjects for coconut dehusking operation with folding and non-folding type dehuskers was 3 (light ) and 4 (more than light ) respectively. The average BPDS score while performing the coconut dehusking operation using folding type and non-folding type manually operated coconut dehusker was 5.8 and 6.1 respectively. Keywords: Coconut dehusker, Dehusking capacity, Dehusking efficiency, oxygen consumption rate, Limit of continuous performance, ODR, BPDS, energy expenditure rate, acceptable workload INTRODUCTION Although coconut is of immense economic importance to both the industrialist and rural area, separation of its husk from the nut (dehusking) constitutes the first, most difficult and drugerous operation in its processing. Dehusking is the process of removing the outer covering called husk from the coconut to get two important commercial products such as copra or dried kernel and fibre or coir. The coconut reaching markets are either partially husked or dehusked as per demand and requirement in distant market. Coconuts meant for distant market place are left with some fibre covering the eyes or on all around the nuts. Such partially husked minimizes the breakage during transportation and attains longer keeping quality. Coconut dehusking is the first step in the preparation of coconut for the fresh market. Dehusking is done manually by impairing the coconut on a sharp iron or wooden spike fixed to the ground. The most frequently used dehusking method is by the use of pointed metal spike, secured in the ground in a slightly slanting position, with the pointed ends upward (Mishra and Sutar, 2007). The nuts are brought down with force on the spike, followed by twisting the nut sideward against the spike, causing loosening of the husk. Care is taken for the desired entry of the sharp end of the spike into the husk so as to avoid the damaging of shell. It is, therefore, clear that dehusking is a hard work, and may cause frequent injury to the operator. This process is laborious and time consuming, moreover it requires skilled laborer. A folding type manually operated coconut dehusker and non-folding type coconut dehuskers were developed at Dr. B S KKV, Dapoli which can be easily transported and safe for operation with reduced the drudgery. The performance and ergonomic evaluation of developed dehusker for its workload on operator, necessity of work rest cycle if needed for continuous performance, estimate energy cost of dehusking operation, assess whether workload is within acceptable limit be evaluated. To assess the ease of coconut dehusking operation by coconut dehusker and Copyright IJAER 2016, All right reserved Page 500

3 drudgery cause in term of Overall rating (ODR) and Body part score (BPDS) be evaluated. MATERIAL AND METHODS Constructional details of manually operated Coconut Dehusker The Dr. Bala saheb Sawant Konkan Krishi Vidyapeeth, Dapoli developed folding and nonfolding type of coconut dehusker was selected for study. Folding type manually operated coconut dehusking unit selected for study consists of foldable base platform, pole, spike blade, detachable handle with grip for easy handling and transportation. Non-folding type manually operated coconut dehusking unit selected for study consists of base platform, pole, spike blade and handle. The both type of the dehusker selected for the experimental purpose as shown in Fig. 1 and Fig. 2 respectively. Specifications of manually operated coconut dehusker are given in Table 1. Sr. No. Table 1 Specification of manually operated Coconut Dehuskers Particulars 1 Base Platform Type A Non-folding (M. S.) 2 Pole 600 (M.S.) 3 Blade Case hardened Steel, Angle Handle Ø 12, 450 (M.S) Type B Folding (M.S. flat 25 4 ) , 1.5 Thick 65 35, 4 thick, tip Width 20 (2 Nos.) Ø 12, 470 (M.S) Detachable 5 Grip - Ø (Plastic) 6 Hinge - 7 Overall dimensions Ø 12, 85 with 17 OD pipe (2 Nos.) Weight 2.90 kg 2.95 kg 9 Size after Folding Non-foldable (All dimensions are in mm) Copyright IJAER 2016, All right reserved Page 501

4 Fig. 1 Folding type coconut dehusker Fig. 2 Non-folding type coconut dehusker Copyright IJAER 2016, All right reserved Page 502

5 Operation of manually operated coconut dehusker The both type of coconut dehusker has one fixed and one movable blade. At normal position, both the blades are works as one unit. The nuts are brought down with force on the blade. After pierce of blade into husk, handle is lifted up which loosen the husk. To completely loosen the husk of coconut, 4-5 strokes have to be given at different positions. After loosening of husk, the loosen husk can be removed manually. Care is taken for the desired entry of the sharp end of the blade into the husk so as to avoid the damage to shell. The coconuts variety Banawali cultiver is selected for performance evaluation. The moisture content of seeds selected for dehusking was in range of % (wb). The number of coconut dehusks per hour, damage percentage and dehusking efficiency was determined by formulae given below. The experiment was conducted with ten different operators. Performance evaluation of Coconut dehusker 1. Moisture content Moisture content of husk is determined by oven drying method as described in ASAE (1982) standards. Moisture content is calculated by using following formulae (Ghoshal and Mohanty, 2011) Moisture Content, wet basis (wb) = Moisture Content, dry basis (db) = 2. Dehusking capacity and efficiency Weight of moist material Weight of dry material Weight of total material Weight of moist material Weight of dry material Weight of dry material X100 X 100 The dehusking capacity and efficiency of the coconut dehusker were evaluated using ten experimental tests. Each test involved operating the dehusker by a different operator. The fifty coconuts were dehusked by each operator and time required for dehusking nuts was recorded. The dehusked husk obtained and total husk in the five selected coconuts were weighed and recorded. Thereafter, the efficiency and capacity of the machine were computed in each case using the following relationship as given by Nwankwojike et al., Copyright IJAER 2016, All right reserved Page 503

6 Dehusking capacity,nut/hr = Number of coconuts dehusked Time,hr Dehusking efficiency, % = Weight of husk obtained after dehusking Weight of total husk present in the coconut X Damage percentage The damage percentage of the coconut dehusked was evaluated using ten experimental tests. Each test involved operating the dehusker by a different operator and recording of the total number of fruits dehusked in a given time. During dehusking process, the total number of damage fruit by each operator was recorded. The damage percentage of the dehusked coconut was computed in each case using the following relationship as given by Nwankwojike et al., Damage percentage, % = Number of damage coconuts Total coconuts X 100 Ergonomic Evaluation of Manually Operated Coconut Dehusker 1. The ten male operators (subjects) for dehusking the coconut were selected as dehusking of coconut is mostly done by male workers. 2. Then each subject was calibrated in the laboratory at sub maximal loads. 3. The value of heart rate at resting level and 6 th to 15 th minute of operation were taken for calculating the physiological responses of the subjects (Tiwari and Gite, 1998). 4. Each subject was asked to dehusked coconut up to 25 min with including 5 min for resting and recovery continuously and during dehusking operation, the HR of subject was recorded by using polar heart rate monitor. 5. From the values of heart rate (HR) observed during the trials, the corresponding values of oxygen consumption rate (VO2) of the subjects for all the coconut dehusker were predicted from the calibration chart of the subjects. Copyright IJAER 2016, All right reserved Page 504

7 6. The energy cost of operation of the coconut dehusker was computed by multiplying the oxygen consumed by the subject during trial period with the calorific value of oxygen as kj l -1 (Nag et al., 1980) for all the subjects. 7. The acceptable workload (AWL) for Indian workers was the work consuming 35 per cent of VO2 max (Saha et al., 1979). To ascertain whether the operation of all the coconut dehuskers is within the acceptable workload (AWL), the VO2 maximum for each treatment was computed and recorded. 8. To have a meaningful comparison of physiological response HR values (Increase over resting values) for heart rate (work pulse) was calculated (Tiwari and Gite, 1998). The mean values of the heart rate at rest level and at working condition were used. 9. For the assessment of overall rating, a 10 point psychophysical rating scale (0 no, 10 extreme ) was used and a body map technique was used to assess the body part score which were an adoption of Corlett and Bishop (1976) technique. 10. Based on energy expenditure rate (EER), acceptable workload (AWL), HR value, VO2 max value, overall rating (ODR) and body part score (BPDS), the energy grade of coconut dehusking operation with selected coconut dehuskers were evaluated. RESULTS AND DISCUSSION It is observed that folding type coconut dehusker perform better than non-folding type coconut dehusker. The dehusking capacity and dehusking efficiency for folding and non-folding type were found to be 58 nuts/h, 93.7 % and 52 nuts/h, 93 % respectively. No damage was observed during operation by both the dehuskers. This may be due to higher height of vertical trunk/post, comfortable handle grip and sufficient footrest platform to hold coconut dehusker rigidly. Ten male subjects were selected for the ergonomic investigation of manually operated coconut dehusker. They were selected on the basis of age, stature, body weight. The details of selected subjects for the investigation of coconut dehusker are given in Table 2.The age group of the selected subject varied from 21 and 50 years. The average values of stature and weight of selected subjects were cm and kg respectively. The average heart rates at rest of the selected subjects are varied from to bpm. The predicted average VO2 at rest of the selected ten subjects varied from l/min to 1.30 l/min. The average value of VO2 at rest of Copyright IJAER 2016, All right reserved Page 505

8 selected subjects was l/min. The maximum heart rates of the selected subjects are varied from 170 to 199 bpm. The mean value of maximum heart rate of selected subjects was 184 bpm. The predicted maximum aerobic capacity of the selected ten subjects valid from 1.9 l/min to l/min. The average value of VO2 max of selected subjects was l/min. Table 2 Physiological parameters of subjects participated in manually operated coconut dehuskers ergonomical evaluation Body Average heart Average HR VO2 Age, Stature, Subject weight, Rate at rest, VO2, (max), (max), years cm kg bpm l/min bpm l/min Mean Table 3 Recorded values of heart rate and predicted values of oxygen consumption of subjects for folding and non-folding type manually operated coconut dehusker Subject Folding type Non-folding type HR,bpm VO2,l/min HR,bpm VO2, l/min Copyright IJAER 2016, All right reserved Page 506

9 Mean The mean values of the heart rate from 6 th to 15 th minutes of operation and the predicted values of oxygen consumption for all the selected subjects are shown in Table 3. It is observed that the working heart rate of selected subjects while operating folding and non-folding type coconut dehusker varied from 94 to 118 bpm and 99 to 122 bpm respectively. The mean value of working heart rate of all the selected subjects for folding and non-folding type was bpm and bpm respectively. It is observed that the difference between working heart beats and resting heart beats is below 40 in all subjects for operating both the coconut dehusker, hence all subjects are suitable for doing coconut dehusking for continuously. The corresponding oxygen consumption values of all selected subjects for operating folding and non-folding type coconut dehusker was to 1.30 l/min and to 1.40 l/min respectively. The mean value of corresponding oxygen consumption was l/min for folding type and l/min for non-folding type manually operated coconut dehusker. It is observed that heart rate and oxygen consumption rate of operating folding type coconut dehusker is less than non-folding type coconut dehusker. This may be due to comfortable posture of working with folding type and suitable handle grip provided on folding type of coconut dehusker. The energy cost of operation of dehusking operation was computed by multiplying the oxygen consumed by subject during trail work with calorific value of oxygen as kj/l (Nag et al. 1980), for all subject. The mean values of heart rate and oxygen consumption of all subjects for manually operated folding type coconut dehusker were bpm and l/min respectively. It was revealed from Table 4 that the energy expenditure of all selected subjects varied from 3.22 to 6.45 kcal/min. The coconut dehusking operation was grade as very light when energy expenditure was less than 2.5 kcal/min, light for those three subjects when energy expenditure varied from 2.5 to 5 kcal/min, moderate heavy when energy expenditure varied from 5 to 7.5 kcal/min, heavy when energy expenditure varied from 7.5 to 10 kcal/min, very heavy when energy expenditure varied Copyright IJAER 2016, All right reserved Page 507

10 from 10 to 12.5 kcal/min and extremely heavy when energy expenditure was 12 kcal/min. The coconut dehusking operation with folding type coconut dehusker is light grade. The average value of energy expenditure for subjects operate non-folding type coconut dehusker is more than the folding type coconut dehusker. The dehusking operation using folding type coconut dehusker is easier than non-folding type coconut dehusker may due to its special feature of folding type manually operated coconut dehusker. Table 4 Energy cost of operation of all subjects while operating folding and non-folding type coconut dehusker Subject Energy expenditur e, kj/min Folding type Energy expenditure, kcal/min Energy grade of work Energy expenditure, kj/min Non-folding type Energy expenditure, Kcal/min Energy grade of work Light Light Moderate heavy Moderate heavy Light Light Light Light Light Light Light Light Light Light Light Light Light Moderate heavy Moderate heavy Moderate heavy Mean Light Light The average value of worker HR from 6 th to 15 th minutes when dehusked by different subjects was recorded, OCR of selected subject was recorded. The relative costs of workload during operation were recorded (% of oxygen consumption rate to VO2max). The recorded value for Copyright IJAER 2016, All right reserved Page 508

11 folding and non-folding type dehuskers shown in Table 5.It was revealed from Table 5 that, among all subjects was within the range of acceptable workload i.e. below 35 % of VO2 max. The per cent values of VO2 max for folding and non-folding type coconut dehusker was in the range of 7 to % and of 7.37 to % respectively. The mean value of per cent of VO2 max for folding and non-folding type coconut dehusker was 9.25 % 10.32% respectively. This indicates that coconut dehusking by both manually operated coconut dehuskers was below the acceptable workload and coconut dehusking operation is acceptable to all subject. Table 5 Oxygen consumption rate as percent of VO2 max while operating folding type and non folding type coconut dehuskers Subjects Per cent of VO2 max Folding type Acceptable workload (35 % VO2 max) Per cent of VO2 max Non-folding type Acceptable workload (35 % VO2 max) < AWL < AWL < AWL < AWL < AWL 8.62 < AWL < AWL 8.35 < AWL < AWL 7.37 < AWL < AWL 9.95 < AWL < AWL < AWL < AWL 9.54 < AWL < AWL < AWL < AWL < AWL Mean < AWL < AWL Copyright IJAER 2016, All right reserved Page 509

12 Table 6 Work pulse ( HR) of all selected subjects while operating folding and non-folding type coconut dehusker Subject Folding type Non-folding type HR, bpm LCP,40 bpm HR, Bpm LCP,40 bpm < LCP < LCP < LCP < LCP < LCP < LCP < LCP < LCP < LCP < LCP < LCP < LCP < LCP < LCP < LCP 35 < LCP < LCP < LCP < LCP < LCP Mean < LCP < LCP From Table 6, it was observed that in the case of manually operated folding type coconut dehusker, work pulse of the subjects varied from 63.6 to 84.4 bpm and HR varied from to bpm. The average value of HR was bpm which was less than Limit of Continuous Performance (LCP).In the case of manually operated non-folding type coconut dehusker, work pulse of the subjects varied from to bpm and HR varied from to bpm. The average value of HR was bpm which was less than Limit of Continuous Performance (LCP). This indicates that coconut dehusking with both folding and non-folding type coconut dehusker can be operated continuously without any rest cycle. The values of ODR and BPDS of subjects while operating folding and non-folding type manually operated coconut dehusker are presented in Table 7. Copyright IJAER 2016, All right reserved Page 510

13 Table 7 Overall s rating and Body part score of subjects for the dehusking using folding and non-folding type manually operated coconut dehusker Subject ODR Folding type Scales BPDS score ODR 1 3 Light Non-folding type Scales BPDS score 2 2 No Light No Light Light Light No No Light 6 4 Mean 3 Light Moderate As shown in Table 7, it was observed that the coconut dehusking with manually operated folding type coconut dehusker, the mean value of ODR was 3 which is light operation. The coconut dehusking with manually operated non-folding type coconut dehusker, the mean value of ODR was 4 which is more than light operation. For folding type coconut dehusker, the mean value of BPDS of subjects was 6.45 and non-folding type was The maximum number of intensity levels of pain experienced coconut dehusker was 4 category. It is observed that average BPDS score for coconut dehusking with folding and non-folding manual coconut dehusker is marginal and can be considered at par. This may be due to similar type of operation carried on both the coconut dehusker Copyright IJAER 2016, All right reserved Page 511

14 CONCLUSIONS The following conclusions are made from the study 1. The dehusking capacity and dehusking efficiency for folding and non type coconut dehusker were observed as 58 nuts/h and 93.7 % and 52 nuts/h and 93 % respectively. 2. No damage to coconut shell dehusked were observed with both type. 3. The average recorded values of heart rate and predicted values of oxygen consumption of subjects for folding type coconut dehusker were bpm and l/min respectively and for non-folding type coconut dehsker were bpm and l/min respectively. 4. The average energy cost of operation of subjects while coconut dehusking with folding and non-folding type coconut dehuskers were 4.29 and 4.82 Kcal/min respectively. 5. The average oxygen consumption rate as per cent VO2 max while operating folding and non-folding type coconut dehusker were and l/min respectively. The coconut dehusking operation is within acceptable limit for folding and non-folding type coconut dehusker. 6. The average HR value for subjects while coconut dehusking with folding and nonfolding type coconut dehuskers were and bpm respectively which was less than limit of continuous performance (LCP). 7. The mean value of overall rating ( ODR) of subjects for coconut dehusking operation with folding and non-folding type dehuskers was 3 (light ) and 4 (more than light ) category respectively. 8. The average BPDS score while performing the coconut dehusking operation using folding type and non-folding type manually operated coconut dehusker was 5.8 and 6.1 respectively. Copyright IJAER 2016, All right reserved Page 512

15 REFERENCES Christensen, E. H., Physiological valuation of work in Nykroppa iron works. In W F Floyd and At Wellford (eds), ergonomics Society Symposium on Fatigue, Lewis, London: Corlett, E. N. and Bishop, R.P., 1976.A technique for assessing postural Ergonomics, 19: Ghoshal, M.K. and Mohanty, S.K., Ergonomical study and performance evaluation of different types of coconut dehuskers. International J. of Agric. Engg., 4(1): Nwankwojike, B. N.; Onuba, O. and Ogbonna, U Development of coconut dehusking machine for rural small scale farm holders. Int. J. of Innovation Technology and Creative Engg., (2)3. Shirisha, D., K. Kathirvel and Manian, R Development and Evaluation of Direct Paddy Seeder for Assesing the Suitability to Rural Women. Agriculture Mechanization in Asia, Africa and Latin America. 39(4): Varghese, M. A., Saha, P. N. and Airiya, N., A rapid appraisal of occupational workload from a modified scale of perceived exertion. Ergonomics, 37 (3): Copyright IJAER 2016, All right reserved Page 513