Ergonomics Methods and Work Procedures in Car Manufacturing for Improvement of Quality, Productivity and Health at Work

Doctoral thesis, 2009

Many studies have concluded that there are great human and economic gains in finding ergonomically sound solutions as early as possible in product and production development. Hence, the objective of the research presented in this thesis was to evaluate methods for improved ergonomics assessment in early phases of product and production development and in production. A further objective was to obtain crucial quality and economics data for existing assembly solutions in order to extract knowledge and quantitative facts that can support decision making in the development of economic and ergonomic assembly concepts in new car programs. A new production engineering method, ErgoSAM, was evaluated by comparison of the assessment results of an existing company method with the results of the new assessment method. This was done through observation, filming and analysis of assembly sequences in car production. In product and production development, virtual methods were evaluated with respect to the possibility of early ergonomics risk analysis. Through analysis of assembly sequences, interviews of project engineers and following the build of a new vehicle both in virtual and physical reality, virtual ergonomics simulation methods were evaluated. A Corporate Ergonomics Program was studied with respect to the work environment organization, distribution of responsibility, methods, routines, documents and achievements. Finally, an analysis of the relationship between assembly ergonomics, ease of assembly and product quality was made. 55 assembly tasks at high, medium and low physical work load were analysed during eight weeks in car assembly and another 16 weeks for factory-complete cars. The costs for correction of quality errors related to the 55 assembly items were collected and cost-calculations were made. The research confirmed that both ErgoSAM and the virtual ergonomics simulation tools showed considerable promise but needed further improvements. Furthermore, training in ergonomics and in usage of the tools was considered to be of vital importance for adequate outcome of results. The Corporate Ergonomics Program demonstrated a macroergonomics approach. Important conditions for success were management support, training in ergonomics and linking ergonomics principles to the company strategy. The program resulted in improved cooperation and feedback between stakeholders, decreased absenteeism and personnel costs. The cost-benefit study showed increased risks for quality errors of 3.0 and 3.7 times and total correction costs that were 8.7 times and 8.2 times higher for high and medium load assemblies compared to low physical load assemblies for the 55 tasks analysed. The overall conclusion is that there are huge savings and increased profit margins to make by elimination of ergonomics risk solutions at early stages in the product realisation process.