Assessment of ergonomic methods for the quantification of biomechanical load in manufacturing systems

The Italian legislation, D.Lgs 81, obliges the employer to evaluate all risks, including the biomechanical risk, for guaranteeing the health and safety of workers according to the technical standards. The assessment of the biomechanical load risk consists in the evaluation of the musculoskeletal efforts, quantifying the main biomechanical factors correlated to musculoskeletal disorders: applied forces, repetitive movements, postures engaged during the working tasks and the net duration of the working tasks taking into account adequate recovery periods. The Ph.D. subject focused on physical ergonomics for manufacturing system and it is born in the framework of the agreement of research cooperation signed by Fiat Grouped Automobiles and Politecnico di Torino. In a first step of the research activity, the methods of risk assessment mentioned in the legislation and widely recognized in the literature were analyzed to evaluate their applicability in different industrial contests. The methods of risk assessment mentioned in the standards are simple observational techniques that consist in pro forma sheet methods and are applicable in specific industrial realities as they refer to particular technical actions and body districts. These characteristics of the methods imply limits of applicability in complex industrial realities, as for example assembly lines. D.Lgs 81/08 also obliges workplace and plant designers to comply with general principles of prevention and protection of the health and safety of workers already at the design phase. D.Lgs 81/08 directly correlated to the Machinery Directive, that requires compliance with CEN standards related to Safety and Ergonomics for all new or updated machineries. Applicability of observational methods in the design phase is limited because, at this stage, data necessary to correctly compile methods may be lacking. With reference to the trend that can be observed in the scientific literature, holistic assessment of the risk as well as multi method evaluation should be applied in order to allow, in the next phases of prototype and production, a deeper understanding of the different main risk factors relating to each body districts.After defining benchmarking parameters, an experimental procedure of method evaluation was programmed. Significant samples of workstations were collected and analyzed in order to assess the robustness and the compliance of some methods of particular interest for application in the design phase (Simulation tools, Checklist di Torino and EAWS method) with respect to the methods mentioned in standards. In a second step of the research work, in collaboration with the sector of Ergonomics and Work Medicine of the University of Turin, focus was posed on the improvement and validation of a first screening tool for the holistic assessment of the biomechanical risk of different body districts. The experimental procedures developed in the first phase of the research activity were used to determine suitable cut–off values for the traffic light indication according to legislation. This tool answers to the current demands for having simple and user-friendly tools and methods for the risk assessment and management to use in the design and screening phase by national and international agencies as well as operators of small and medium enterprises. It’s worth to remember that these kind of tools and methods must be reliable with respect to methods mentioned in standards, in order to assure compliance with the legal requirements.