"The typical seru implementation process can be summarized as follows:
1. As customer demands fluctuate, assembly line inefficiencies become apparent and a strategic choice to emphasize responsiveness is made.
2. Assembly lines are dismantled and replaced with divisional seru systems through resource collocation and removal/replacement, cross-training, and autonomy.
3. Expensive dedicated equipment is replaced by inexpensive general-purpose equipment that can be duplicated and redeployed as needed by serus.
4. As cross-training progresses, divisional serus evolve into rotating serus and yatais.
5. As the seru system matures, cell configurability is developed so that exactly the cells required to meet demand can be rapidly formed, then dismantled once demand is met.
In the years leading up to 1992, production of most high- volume, low-value-added Japanese products was being shifted to low-cost countries because of the Japanese yen's sharp rise. Sony's products did not lend themselves to such offshoring, however, because they were characterized by high variety, low volume, and high value added, with frequent design updates and generational changes. Sony first attempted to respond to its high demand volatility by applying the Toyota Production System mixed-product method to its conveyor lines, but the demand volatility for Sony products substantially exceeded that of Toyota. Rapid changes in product technologies and configurations called for lines to be reconfigurable, whereas the Toyota Production System emphasized investments in expensive, synchronized, integrated production lines. Thus, Sony chose to design its production system to respond to demand volatility, rather than eliminate it as occurs under the Toyota Production System.
Conveyers were replaced by workbenches, and simple equipment and manual tools were used, so that serus could be constructed, modified, dismantled, and reconstructed quickly and frequently. Although divisional serus were considerably more flexible than assembly lines with respect to product variation and volume changes, the demand for some products was volatile enough to require even more flexibility, so some of the divisional serus were converted into rotating serus.
As product variants proliferate and product life-cycles shorten, needs for changeovers and transitions rise. In this case, assembly lines with highly specialized workers and equipment (and resulting costly and lengthy change- overs) are likely to struggle more and more to maintain acceptable levels of utilization (uptime). Given the need to meet these highly varying demands, seru systems actually produce swifter and more even flows than assembly lines, because they handle transitions more quickly and efficiently. The emphasis under seru that all tasks are completed in a single cell, all required resources are made available in the cell, and that everything not required is eliminated, has as its objective to support the swift and even flow of products."