Use of work equipment, tools, and other mechanical means in industrial activities enhances productivity and physical capacities of workers. But excessive use of poorly designed tool affects workers’ occupational health and are found to be a major reason for occurrence of WMSDs (Kumar et al., 2016; Ncube et al., 2019; Sanjog et al., 2016; Thetkathuek et al., 2018). Generally, work equipment can be categorized into two main categories, namely manually operated and automatic. While designing manually operated equipment, one must consider principles of ergonomics.
Consideration of ergonomics while designing tools or work equipment has found to be effective in reducing WMSDs and in increasing user comfort, satisfaction, and productivity (Choobineh et al., 2004; McNeill & Westby, 1999). For example, Patel et al.(2017) developed a manually operated paddy thresher adaptable to agricultural needs of north-eastern region of India and recommended that improved design of agricultural equipment can reduce discomfort among agricultural workers. Another study by Singh et al. (2012) that designed a hand-operated maize dehusker-sheller using ergonomics reported that physiological workload has reduced over traditional method. McNeill & Westby (1999) redesigned and evaluated a manually operated cassava chipping machine and found that redesigned chipper reduced discomfort and drudgery among the workers. Umar et al. (2019) reported noticeable improvement in the working postures of technicians in manual material handling operation with ergonomic design of manually operated trolley-lifter. Kushwaha & Kane (2016) designed a manually operated crane cabin workstation and recommended that
adopting an ergonomic based intervention in workplace greatly reduce mismatch between man and machine interaction. Sanjog et al. (2019) implemented a contextual design intervention from occupational ergonomics perspective and reported reduction in operator cycle time as compared to traditional operations. Jadhav et al. (2019) designed an ergonomic stitching workstation in footwear industry based on user requirements and ergonomic guidelines of workstation design. They found that the workstation design was effective in reducing postural workload. These studies highlighted that ergonomically designed work equipment is advantageous in terms of improving work and work methods, providing comfort to the user, reducing postural stress, and enhancing productivity.
By adopting a participatory approach to design and paying close attention to ergonomics aspects, a hand-operated cashew nut sheller was conceptualized and has been reported in detail in the previous chapter. The simulation-based evaluation of the sheller was found to be fairly satisfactory in terms of reducing musculoskeletal risk due to awkward postures. A sheller of such kind should be constructed in developing countries like India for small-scale processors and at village level application. The construction of a physical prototype, field testing, and feedback of users are essential to determine its long-term impact. In order to develop a physical prototype model, one needs to determine necessary dimensions of work equipment and anthropometric measurements of users. Researchers showed that a mismatch between anthropometric dimensions and equipment dimensions contributes to discomfort, biomechanical stress, and reduced productivity. On the other hand, the application of anthropometric data in design development is very much useful for a better fit between man and machine (Bhattacharjya & Kakoty, 2020). It also provides comfort to users and minimizes the risk of WMSDs. Bhattacharjya & Kakoty (2020) showed that the application of anthropometric data for designing pedal-operated Chaak in pottery industry and reported a higher level of comfort among workers. Zadry et al. (2017) designed an ergonomic spinal board based on anthropometric data of Indonesian people in order to improve safety and comfort while evacuating injured patients. So, anthropometry should be considered as an ideal factor during the design process for a good fit between human and the designed equipment.
Evaluation of working posture of workers during the interaction with work equipment and elements of work equipment is essential for reducing risks of
biomechanical overload in workplace (Burton & WHO, 2010). Due to awkward working posture, workers’ mental and biomechanical load may increase (Caffaro et al., 2018; Hallbeck et al., 2010) leading to WMSDs in different body regions (Mukhopadhyay & Ghosal, 2008; Patel et al., 2017). There are few international standards (EN 1005-4:2009, 2009; ISO 11226:2000, 2000; ISO 11228-3:2007, 2007) that have been developed to define risk assessment methods to evaluate postural stress referring to work activity, equipment characteristics, and human-machine interaction.
These standards are aimed to protect workers’ health and safety.
Rapid Upper Limb Assessment (RULA) (McAtamney & Nigel Corlett, 1993) and Rapid Entire Body Assessment (REBA) (Hignett & McAtamney, 2000) are the two simple methods for assessing occupational postural risk. According to World Health Organisation (WHO) and International Ergonomics Association (IEA), both RULA and REBA are most cited among the selected tools for prevention of WMSDs (Enrico Occhipinti & Colombini, 2012). These methods are also referenced across international standard for occupational risk assessment (ISO 11228-3:2007, 2007).
Indeed, previous studies also showed that observational methods are reported to be effective in biomechanical work-related load assessment. These are also advantageous in terms of being more versatile and less expensive compared to objective methods when time and resources are considered. While assessing specific work activity using RULA and REBA, these methods give a numerical index that quantifies workers’
exposure to musculoskeletal risk and recommends the level of intervention required based on risk level. RULA method is applied to identify neck, back, and upper limb postural disorders in relation to muscular action and external loads applied on the body. The REBA method is suggested for identification of postural disorders of the whole body in relation to external loads applied on the body, muscular action, and the type of grip. Furthermore, these methods have been widely applied in industrial activities (Garosi, Mazloumi, Kalantari, Vahedi, & Shirzhiyan, 2019; Kumar et al., 2016; Kushwaha & Kane, 2016; Patel et al., 2017;Qureshi & Solomon, 2021; Sakthi Nagaraj et al., 2019; Umar et al., 2019) for quantification of biomechanical overload risk.
In developing countries like India, most of the industrial operations depend on manually operated equipment, and workers spend long hours interacting with them.
Assessing postural aspects during human-machine interaction has been constantly
under investigation. With regard to manual equipment, cashew nut sheller is the most widely used work equipment in cashew processing industry. The attention to this manual equipment is increasing because of high-level quality of yield (Ajav, 1996;
Ojolo & Ogunsina, 2007) and incidence of WMSDs among workers. Given the importance of shelling equipment, the aim of the present study reported in this chapter was to construct a hand-operated sheller and to compare its postural risk with the conventional sheller.