This is to certify that the work contained in this thesis titled "Design and Evaluate an Ergonomic Intervention to Reduce the Risk of Musculoskeletal Disorders in Indian Small and Medium Scale Cashew Nut Processing Mills" submitted by Mr. Next, it provides the design and evaluation of an ergonomic intervention to reduce the risk of musculoskeletal disorders in Indian small and medium scale cashew nut processing mills from an ergonomic perspective.
Global cashew nut industry
It presents the background of the study – highlighting the current scenario of cashew processing in India and the need for ergonomically based research in the Indian cashew industry. According to Azam-Ali & Judge, cashew kernels are consumed in snacks and the rest (40%) is used in confectionery and bakery products.
Indian cashew industry: an overview
Currently, the Indian cashew industry is growing at a faster pace and is focusing on regionalized production centers with the aim of increasing domestic production of raw cashews. Moreover, another favorable factor for the Indian cashew industry is skilled labor (Harilal et al., 2006).
Cashew nut processing in India–Present scenario
Together, these factors make India's small- and medium-scale cashew nut processing sector labor intensive. In light of these issues, there is a need to conduct ergonomic investigations in Indian small and medium scale cashew nut processing plants.
Musculoskeletal disorders and ergonomic intervention
Identification of musculoskeletal problems (if any) and finding ways to prevent these occupational health problems among workers is highly required in Indian small and medium mills. Many studies have reported that designing workstations or work equipment according to ergonomic principles effectively reduces musculoskeletal problems and increases user comfort, satisfaction and productivity (Choobineh et al., 2004; McNeill & Westby, 1999;.
Aim and objectives
Jadhav, Arunachalam, and Salve (2019) designed an ergonomic workstation for sewing in the footwear industry based on user requirements and ergonomic workstation design guidelines. In general, these studies have emphasized that ergonomically designed work equipment is beneficial in terms of improving work and working methods, providing comfort to the user, reducing postural strain and increasing productivity.
Scope and rationale behind present research
As mentioned earlier (Section 1.3), the design of the existing sheller appears to have ergonomic issues that impose postural strain on the workers and can lead to musculoskeletal problems in several body regions. The current study mainly emphasizes the current activity of shelling cashews to address any postural stress that may lead to musculoskeletal problems.
The necessary changes/reorganizations should be adopted to minimize the risk of musculoskeletal disorders. Every effort has been made to propose an ergonomic intervention in accordance with the requirements of the end users.
In this study, a cross-sectional study was conducted in different states of India to determine the severity of the current issue. Based on relevant anthropometric data, a comprehensive and fully functional model of the new cashew nut peeler was developed.
Organization of the thesis
Then it offers a test evaluation of the new cashew shell compared to the traditional existing shell. Chapter – 2: Evaluation of Working Conditions in Small and Medium Scale Cashew Nut Processing Mills in Eastern India.
This chapter examines the current working conditions in relation to the work attitude, prevalence of WMSDs and associated risk factors among workers in Indian small and medium scale cashew nut processing mills. Furthermore, results of logistic regression performed to determine the relationship between WMSDs and potential risk factors (including demographic and work-related factors) were highlighted.
Work-related musculoskeletal disorders and associated risk factors
In particular, WMSDs have been significant problems in Indian agriculture-related industries such as tea leaf pickers (Bhattacharyya and Chakrabarti, 2012), pineapple peelers (Kumar et al., 2016), anole stings (Rai, Gandhi, and Sharma, 2012). ) etc. Many studies also report various occupational factors, including individual (e.g. age, gender), organizational (e.g. job stress, working hours) and environmental (e.g. air quality, temperature) factors that contribute to the occurrence of WMSD in many SMEs in India (Das et al., 2021; Kumar et al., 2016; Nag & Nag, 2007; Sanjog et al., 2015).
Tool for subjective assessment of musculoskeletal disorders
Cornell musculoskeletal questionnaire ("Cornell University Ergonomics Web," 2003), Dutch Musculoskeletal Questionnaire (DMQ) (Hildebrandt, Bongers, Van Dijk, Kemper, & Dul, 2001), and standard Nordic Musculoskeletal Questionnaire (NMQ) (Kuor,inka. 1987 ). The limitations of the NMQ include: (a) the interviewer bias that may affect results, and (b) participants' ability to recall—mostly they recall most recent or more severe MSDs (Kuorinka et al., 1987).
Postural evaluation tool for entire body assessment
Materials and methods
- Description of work activities
- Study design
- Statistical analysis
The first part of the questionnaire collected data on demographic details (gender, age, height, weight, marital status, education level, work activity and smoking habit). Demographic and work-related characteristics of the study population were reported as mean (standard deviation), frequencies, and percentages.
- Demographic details
- Work-related details
- Prevalence of WMSDs
- Working posture assessment
- Risk factors for WMSDs
Odds ratios (OD), p-value and 95% confidence intervals (95% CI) were used to describe the association between WMSD prevalence and study variables. The prevalence of WMSD among different body regions as reported by cashew workers is presented in Table 2.3.
Prevalence of WMSDs
Variables Upper back Lower back Knees Ankles/feet. in the lower back and knees. 2020) highlighted that the prevalence of weapons of mass destruction can have a significant impact on the health and well-being of workers.
Factors associated with WMSDs
This finding is in agreement with a previous study reported from Kerala (Girish et al., 2012). It has previously been reported that extended working hours in several working groups contribute to the development of weapons of mass destruction (Kumar et al., 2016; Thetkathuek et al., 2018).
Work stress: Several studies showed a statistically significant relationship between work stress and WMSDs in different parts of the body (Sakthi Nagaraj, Jeyapaul, & . Mathiyazhagan, 2019). In the present study also, there is a significant association of work stress with back disorders with an odds ratio of 3.51.
Chapter 2 summary
The findings of this study warrant an ergonomic design intervention to improve working conditions in small and medium-sized cashew nut processing mills. Therefore, this chapter presents a systematic process of devising an ergonomic design intervention to solve the problems of cashew nut shelling.
In Indian small and medium scale cashew nut processing plants, cashew nut grinding is a major activity where workers usually use hand pedal cashew nut cutter to cut ripe cashew nuts. In this activity, workers are required to adopt difficult work postures for long periods, which contributes to the occurrence of WMSD.
Cashew nut shelling activity and shelling equipment
Narsia (2020) also highlighted that the awkward postures and repetitive actions are mainly attributed to WMSDs among shellers. However, investigations on redesigning existing cashew shell to improve the health and productivity of shell workers are rare in Indian scenario.
Cashew nut sheller design – A review
It consists of two knives (upper and lower knife) with a cashew nut outline. During the shelling operation, the cashew nut is subjected to cutting-cutting to extract the kernel.
Considerations for a design intervention – An ergonomic perspective
Depending on the type of work to be performed, the height of the work surface must have a certain relationship with the height of the operator's elbow. According to Konz (1967), the height of the work surface should be ± 5 cm above elbow level.
Participatory approach and computer-based simulation tools
Therefore, designing work equipment based on ergonomics and anthropometric data is strongly required (Sharma et al., 2021). Some researchers ensured good face validity of DHM after testing the effectiveness of design interventions (Jadhav et al., 2019; Kushwaha & Kane, 2016; Sanjog et al., 2016).
Redesign of existing cashew nut sheller
- Design brief
- Study location and participant recruitment
- Introductory meeting
- Reasons for not using semi-automated and automated equipment
- Identification of user requirements
- Generation and screening of design alternatives
As a result, a total of 15 pre-screened user requirements have been identified and defined, as shown in Table 3.3. The correlation matrix is built to find the existing relationship between user requirements and design requirements.
Simulation-based evaluation of redesigned sheller
- Creation of digital human model
- Posture analysis
- Visibility analysis
- Clearance analysis
- Results of RULA
- Results of visibility analysis
- Results of clearance analysis
The RULA dialog box displays the details, including the final score for the work position and the score for each body segment. The results of thigh clearance analysis conducted for three dummies in this study revealed the clearance values as 59 mm, 102 mm and 101 mm for 5.P, 50.P and 95.P respectively.
The height adjustment pin provided at the bottom of the seat will accommodate a wide range of people. These adjustment features provided in the redesigned shell will eliminate ergonomic and anthropometric problems of the users.
Chapter 3 summary
This chapter demonstrates the development of the full-scale model of a hand-operated cashew nut sheller and reports field test data conducted to determine its role in addressing the awkward working posture of shelling workers and high musculoskeletal strain. It is reported in this chapter that a manual sheller provides a comfortable physical position at work and is useful in reducing the musculoskeletal strain on various body parts of shellers.
The simulation evaluation of the shell was found to be quite satisfactory in terms of reducing musculoskeletal risk due to awkward positions. The REBA method is recommended for the identification of postural disorders of the whole body according to external body loads, muscle function and type of grip.
Structure of cashew nut
Physical dimensions of cashew nut
In terms of hand equipment, cashew sheller is the most used work equipment in the cashew processing industry.
Basic considerations for the development of cashew nut sheller
Development of hand-operated cashew nut sheller
- Sheller unit design
- Seat design
- Table design
- Final design
- Working principle of hand-operated cashew nut sheller
Based on the final simulation format and detailed drawings, a prototype hand-operated cashew nut cutter was built. Most of the components used in the development of the manual operation were sourced and fabricated in a local workshop.
Application of anthropometric data
- Handle length
- Handle diameter
- Seat width
- Seat length
- Seat forward-inclination
- Seat height
The hand width values of 5th percentile men, 50th percentile men and 50th percentile women were added. The seat length is determined based on the buttock-popliteal length of female population according to Mehta et al.
- Posture assessment
- Comparison of tasks in shellers
- Results of posture analysis
- Results of task analysis
The foot pedal is pressed down; so the cashew nut is pressed with the blades. In the new peeler, a cashew is grabbed with the left hand and placed between the blades.
However, the RULA score for inserting cashews with a manual peeler was 5, indicating further investigation and modification. Overall, the developed manual cashew nut peeler was well received and liked by all participants.
Chapter 4 summary
During an informal meeting with the participants, most of them felt that the hand-operated forerunner improved their work posture. Finally, the main contributions, limitations and suggestions for future work are highlighted in this chapter.
Salient findings from present research work
Analysis of musculoskeletal disorders revealed that the prevalence of WMSDs was high among cashew workers in Indian small- and medium-scale cashew processing factories. In the second phase of the study, the activity of cashew nut peel was selected for further investigation.
Achievement of research aim
The number of steps performed in a hand-operated cashew sheller was less 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.
Fulfillment of the objectives
Overall, this study provided a detailed overview of the current working conditions in Indian small and medium-sized cashew nut processing mills. After an extensive review of existing shell designs (Chapter – 3; Section 3.3) and with reference to similar tasks, a new shelling method for cashew nuts was developed.
Contributions of the present research work
It was demonstrated that the new sheller could be operated with one hand instead of the hand and foot pedal required in the existing sheller. After a virtual ergonomic simulation, a full-scale model of a hand-held sheller was developed through the application of anthropometric data and tested with users.
Limitations and suggestions for future work
In the present work, no attempt was made to determine the effects of hand-operated sheller on worker performance. Therefore, we strongly recommend worker training and further field trials to test the effectiveness of hand-operated sheller under real production conditions.
Chapter 5 summary
Prevalence and risk factors associated with musculoskeletal disorders among cashew nut shellers in India. Development of compact machines for shelling cashew nuts (part 2): testing and evaluation of manual and semi-automatic shellers.
Questionnaire used for data collection
Rapid Entire Body Assessment (REBA)
Questionnaire survey for the user requirements
Rapid Upper Limb Assessment (RULA)
Name and specifications of the items used for fabrications of hand-
Fabrication and specific mechanical operations
The actual use cases of completing shelling activity using hand-
List of publications