A Review: Practice and Theory in Line-Cell Conversion

Abstract

Since the 1990s, Japanese manufacturers had been faced with a dynamic production environment of decreased market demands and increased product variations. To survive in such an extremely tough business environment, the traditional high-volume conveyor assembly lines were no longer fulfilled. Speedy adjustments were needed to handle transitions in product models and demands. A company’s competitiveness was becoming dependent on whether or not it can respond to these transitions. Instead traditional conveyer assembly line, several flexible manufacturing methods were developed to handle the outside changing factors like as varying product types, smaller batch sizes, varying task sizes, and inside changing factors like as flexible layout and planning, cross-training of workers. These challenges and innovations of manufacturing methods have resulted a remarkable improvement in productivity, reduction on capital investment, shortened lead times, saving of manufacturing work space, improvement in product quality, decreasing work in process and parts storage, and so on. Traditionally, such innovations have been called totally Seru Seisan (cellular manufacturing or shorten it by CM) in Japan, because the system was adopted usually a U-shaped layout in which one (or multiple) worker carries out all of the operations of a job. However, even it is not a problem in Japan because the special characteristic of Japanese, the naming may confuse the understanding of the innovations against traditional cellular manufacturing. In fact, we refer the new innovations now in Japan include the traditional cellular manufacturing. For example, Tanaka (2005) reported that there are seven manufacturing methods have been used to correspond the new manufacturing in RICOH UNITECHNO Inc., which is a middle scale Japanese company to manufacture facsimiles/copy machines/printers. Those methods are as follows: (1) One worker-One machine method (the product will be assembled by only one worker, he should do all of the assembly operations); (2) Two workers-One machine method (there are too operational works to assemble for a larger machine that can not complete by one worker, in such case two workers should be assigned to do this assembly operation); (3) Cart pulling method (instead conveyor line a cart is used as transport tool, which is pulled among several workers to complete the