The impact of materials feeding design on assembly process performance

Journal article, 2009

Purpose - The purpose of this paper is to provide an understanding of how the materials feeding design at a workstation impacts the assembly process performance, in terms of manufacturing flexibility, process support, materials planning and work task efficiency. Design/methodology/approach The empirical data are based on two embedded case studies performed in close corporation with two Swedish automotive companies; additional observations from more than 20 company visits in Japan, and small-scale case studies performed in Japanese companies. To fully assess the work measurement figures, video recordings, work instructions and layout drawings were used to plot the operatorswalking patterns, and it was then possible to map the whole work cycle for an operator. Industrial engineers, anagers, group leaders, team leaders and operators were interviewed. Based on the literature review and personal experience from the small-scale case studies carried out in Japan, the existing assembly systemscomponent racks were conceptually re-designed. This led to two hypothetical assembly systems, which could be used for understanding the impact of materials feeding design on assembly process performance. The design of the new component racks and the choice of packaging types were made together with practitioners. Findings The paper shows that the design of component racks and choice of packaging types have a major impact on the assembly process performance. Component racks with a large depth and small width and tailored packages create important advantages over traditional Swedish component racks designed for EUR-pallets. Line stocking is not always the best choice for materials feeding, but this paper shows that line stocking, especially in Swedish assembly systems, can be improved. Sequencing can thus be reduced, resulting in fewer problems when there are sequence breaks in the production flow. Component racks with small packages and large depth increase the work task efficiency, volume, mix, new products and modification flexibility. For example, free space is an important issue for these types of flexibilities. Component racks that are portable and easy to rearrange, together with free space, greatly facilitate handling of new product introductions or modifications of products. The new and old component can be displayed and fed to the same workstation, and if there is a larger change a whole segment of a component rack can easily be replaced by a new one between work shifts. Research limitations/implications - The scope of the study is limited to the conditions at workstations. Consequences for the materials flow upstream (i.e. internal materials handling, warehousing, transport, supplier processes, etc.) are not included, but must in further studies also be considered to avoid sub-optimisation. Originality/value - The paper highlights the fact that a shift in focus is necessary when designing workstations with component racks in Swedish companies, meaning that operators become the customers rather than the transport company or materials handler.