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Salient findings from present research work

In document Cashew Nut Processing Mills (Page 114-119)

The salient findings from the present research work are presented under three separate phases as:

o Phase I: A cross-sectional study to evaluate the existing working conditions in Indian small and medium-scale cashew nut processing mills

This first phase of the thesis reported the findings of a cross-sectional study that was conducted across four different states (Andhra Pradesh, Orissa, Assam, and Meghalaya) of India. Since not much work had been reported in the area of occupational health of cashew workers, an effort was made to demonstrate the occupational health of cashew workers in Indian small and medium-scale cashew nut processing mills. During the survey, the working conditions in small and medium- scale cashew nut processing mills were closely observed and work activities across different work sections, namely boiling, shelling, peeling, and grading, were observed, and insights were recorded. Demographic and work-related characteristics were collected through a questionnaire. Information related to the prevalence of musculoskeletal disorders was collected using Nordic Musculoskeletal Questionnaire (NMQ). Digital photography and video recording techniques were used to document the work activities in the factories. The work activities involve both upper and lower body parts. Therefore, Rapid Entire Body Assessment (REBA) technique was used for postural assessment. The relationship between WMSDs and demographic and work- related risk factors was analyzed using logistic regression analysis. The following are the main conclusions that were drawn from the first phase of the investigation.

i. The cross-sectional study was conducted on 290 cashew workers, and the sample included 73.4 % females and 26.6 % males from four different work activities. The activities and sample percentage are: boiling (11.4 %), shelling (51.8 %), peeling (22.0%), and grading (14.8 %).

ii. Participants were aged between 19 and 65 years (Mean = 35.0; SD = 9.1), and around 79 % participants were married. Their work experience ranged between 1 and 30 years (Mean = 8.5; SD = 5.8), and their mean daily working time was 9.6 hours per day.

iii. Musculoskeletal disorder analysis revealed that the prevalence of WMSDs was high among cashew workers in Indian small and medium-scale cashew nut processing mills. Around 70.3 % of the cashew workers had experienced discomfort in at least one body region during the past 12 months. Among them, females reported high prevalence of WMSDs than males.

iv. Shoulders, lower back, hands/wrists, and knees were found to be the most commonly affected body regions, and their prevalence rates were 52.4 %, 51.4

%, 43.4 %, and 35.9 %, respectively.

v. With regard to the prevalence of WMSDs among workers in examined work activities, shelling activity workers were found to report higher prevalence compared to other activities.

vi. Analysis of working postures of cashew workers using the REBA showed that most of the workers’ postures were at high and very high risk and required immediate investigation and change.

vii. Analyses of logistic regression revealed that work-related factors including work experience, job stress, daily working time, work fatigue, and demographic factors (age, gender, educational level, marital status, and type of work activity) were significantly associated with WMSDs.

viii. Logistic regression also showed that the type of work activity, particularly shelling, had a significant relationship with WMSDs. The shelling activity workers were found to be 5.34 (odds ratio) (95 % CI: 2.12 – 13.44) times more likely to develop knee disorders than boiling workers.

ix. Overall, the field assessment of problems in Indian small and medium-scale cashew nut processing mills revealed the complicacy of cashew nut shelling activity where the majority of shelling workers suffered from prevalence of musculoskeletal disorders and adopted postures that were risky while using existing shelling equipment.

o Phase II: Ergonomic design and simulation-based evaluation of a cashew nut sheller

In the second phase of the study, cashew nut shelling activity was selected for further investigation. The workers in shelling operation used conventional hand-cum-pedal operated sheller. The design of the existing sheller is mainly attributed to causing musculoskeletal disorders among sheller workers. In order to identify the ergonomic and design issues related to existing cashew nut sheller, direct observations and focus group meetings involving the stakeholders were conducted in four selected small and medium-scale cashew nut processing mills in Andhra Pradesh, India. Through the meetings, initial user requirements related to redesign of existing cashew nut sheller were collected. Using grouping/combining/eliminating technique, the initially

collected user requirements were screened and finalized. With an intention to provide customer satisfaction and a more acceptable solution, a methodological design tool, Quality Function Deployment (QFD) approach, was used. Preliminary concept sketches were generated and screened based on the initial information and previous interactions with the stakeholders. Following the participative design process, a simple, improved, and desired cashew nut sheller design (CAD model using CATIA V5 software) was conceptualized. To check the compatibility of redesigned sheller, virtual simulation using the digital human modeling technique was performed. Three digital human models representing 5th percentile, 50th percentile, and 95th percentile were developed based on Indian anthropometric database. Rapid Upper Limb Assessment (RULA) tool was used to assess the working posture in redesigned sheller. Vision analysis and thigh clearance analysis were also conducted to check the effectiveness of the new design. The following are the main conclusions that were drawn from the second phase of investigation.

i. Even though various semi-automated and automated shelling equipment were developed and patented by different researchers from India and other countries, the commercial use of such equipment is scant in India. Some of the reasons which contributed to this were found to be: limited capital investments, lack of effective operational knowledge and technical support, seasonal nature of production, lack of electricity, and recovery of whole kernels.

ii. In this context, the focus group meetings with thirteen stakeholders has resulted a total of 45 initial requirements for redesigning existing cashew nut sheller. The screening of these initial requirements using grouping/combining/eliminating gave fifteen final user requirements.

iii. A questionnaire survey including the finalized user requirements was conducted on thirty randomly selected participants. The computed Cronbach’s alpha was 0.75, which indicated acceptable reliability of survey questionnaire.

iv. Based on the user requirements and interaction with stakeholders, three preliminary design concepts of redesigned existing cashew nut sheller were generated in the present study. A final concept, the vertical hand-operated cashew nut sheller with seat, was finalized by the users. Some important design features of redesigned cashew nut sheller are (1) Hand lever (2) V-

shaped blades (3) Sheller unit frame (4) Seat surface (5) Height adjustment pin (6) Shelling table frame (7) Dropping chute (8) Container.

v. Simulation-based evaluation of redesigned cashew nut sheller was performed using digital manikins (5th P- short (female), 50th P- medium (male), and 95th P- large (male)) to check its effectiveness.

vi. The results of the simulation-based evaluation revealed that the redesigned cashew nut shelling equipment is effective in reducing the risk of harmful postures.

vii. The vision analysis and thigh clearance analysis were also satisfactory. The head flexion has improved, and there is enough gap (thigh clearance) between the manikin and the redesigned sheller.

o Phase III: Development and evaluation of a new cashew nut sheller

The third phase of the thesis reports the construction and evaluation of the newly developed sheller. Using appropriate anthropometric data of thirty shelling workers from the field, an ergonomically improved cashew nut sheller was developed. Digital photography and video recording techniques were used to field test the redesigned sheller. Rapid Upper Limb Assessment (RULA) and Rapid Entire Body Assessment (REBA) methods were used to evaluate the new sheller and a comparison test was conducted with the existing one. The number of steps to complete shelling using existing and redesigned sheller was compared.The following are the main conclusions that were drawn from last phase of present investigation.

i. The construction of a hand-operated sheller was carried out by the application of anthropometric data of thirty random participants from the local population.

The specifications of important machine elements are: handle length = 105 mm; handle diameter = 44 mm; seat width = 450 mm; seat length = 400 mm;

table area = 850 mm X 600 mm.

ii. The method of shelling has been changed in the new sheller. In the existing sheller, both hand and leg were used for completing the shelling of the roasted cashew nut, whereas use of hands can accomplish the shelling operation in the new sheller.

iii. Filed testing results showed that the grand scores for both RULA and REBA had improved and indicated working postures in the redesigned cashew nut sheller were safe.

iv. The number of steps performed in a hand-operated cashew nut sheller was lesser than the conventional sheller.

Considering ergonomic design and evaluation, it can be concluded that the hand-operated cashew nut sheller developed based on ergonomic principles and anthropometric data is useful in improving the working conditions of the shelling activity across small and medium-scale cashew nut processing mills in India.

In document Cashew Nut Processing Mills (Page 114-119)