The National Science Foundation's (NSF) Tokyo Office periodically receives and disseminates reports on research developments in Japan that are related to the Foundation's mission. NSF-sponsored researchers currently working in Japan prepare many of these reports. These reports present information for use by NSF program managers and policy makers; they are not statements of NSF policy.
Special Scientific Report #99-19 (November 17, 1999)
Mr. Guy Bear Sindjou, a graduate student in Industrial and Systems Engineering at Virginia Polytechnic Institute and State University, prepared the following report. Mr. Sindjou was a participant in the 1999 Summer Institute sponsored in the United States by NSF/NIH/USDA and the Science and Technology Agency and Japan Science and Technology Corporation in Japan. Professor Fumihiko Kimura of Department of Precision Machinery Engineering, University of Tokyo, hosted Mr. Sindjou. Mr. Sindjou can be reached via email at: moumie@hotmail.com
Introduction:
Industrial mass production of consumer goods has produced enormous concerns about our environment. In Japan particularly, Tomiyama, et al, tell us that as of 1999, 50 million tons of general waste, resulting from households and offices, are disposed of annually. For industrial waste, about 400 million tons are disposed of annually, creating serious problems for the limited waste landfill capacity. Tomiyama adds that in about 2 to 3 years, current sites for industrial waste are projected to be filled up and that construction of new sites is very problematic (1).
Product designers and consumers have become aware of these serious environmental issues and have engaged in conceptualizing environmentally friendly products. Different product life cycle design strategies have emerged to control the impact of industrial waste. Kimura has proposed a strategy called inverse manufacturing which makes the whole product life cycle visible and controllable, and stresses the controllability of product reuse/recycle processes to promote closed loop products and material circulation (2).
Under the same concept of inverse manufacturing, several life cycle strategies could be adopted based on product requirements. Sakamoto, et al, proposed rapid product life cycle to increase the quality requirement of products whose functions tend to become obsolete faster than their actual physical life span. This strategy proposes rapid recollection of products and improvement of its modules and functions (3). However, although very effective in maintaining certain products fast growing quality requirements, this strategy also produces some level of waste relatively important compared to other strategies.
The current study extends Sakamoto, et al's, work and attempts to assess the waste effect of rapid product life cycle as compared to ordinary product life cycle, which differs from the former by its longer recollection time due to its relatively longer product quality requirements. Simulation of the waste effect of both strategies was conducted using a Japanese air conditioner as a case study.
Definitions:
Ordinary life cycle is defined in this study in terms of products with long lives, evaluated at 750 time steps before complete disposal. We assume that after disposal, products are mostly obsolete, and are not put back into the market, but are inspected for modules that can be reused/upgraded/refurbished or recycled.
Rapid product life cycle is defined in terms of products with shorter life cycles, evaluated at 150 time steps before being taken back. When products are returned to the manufacturer, they are inspected for the same reasons as above. Also functions are improved according to customer requirements, and then the product is returned for the customer's use. Fig.1 describes a generic product life cycle waste.
Life Cycle Waste Model:
Description of simulation:
When a product reaches its disposal time it is collected, disassembled, and inspected. During inspection, modules are examined and those which fall within defined a reuse are reused/upgraded/refurbished. Components which fall within b recycle are recycled, and the rest are considered waste. The initial quality of the modules of the entire product quality is assumed to be equal to 1.
2a: Quality control by rapid product life cycle 2b: Recycle
index
showing reuse index (Sakamoto et al., 1998)
Theoretical value parameters:
In choosing values for the simulation we assumed that in general a for rapid life cycle will be lower than that for ordinary life cycle. In other words, rapid life cycle produces more reusable modules. b has been chosen under the assumption that more module weight can be recycled in rapid life cycle, producing lower waste, therefore giving them higher b 's.
Table 1: Value parameters for air conditioner's life cycle waste simulation
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| Rapid Life Cycle | Ordinary Life Cycle | Rapid Life Cycle | Ordinary Life Cycle | Rapid Life Cycle | Ordinary Life Cycle | |
| Compressor(M0) | 10.0 | 10.0 | 0.9 | 0.7 | 0.6 | 0.8 |
| Evaporator (M1) | 3.0 | 3.0 | 0.9 | 0.7 | 0.7 | 0.9 |
| Condenser (M2) | 5.0 | 5.0 | 0.9 | 0.7 | 0.7 | 0.9 |
| Air Filter (M3) | 0.1 | 0.1 | 0.7 | 0.7 | 1.0 | 1.0 |
| Control Unit (M4) | 1.0 | 1.0 | 0.6 | 0.4 | 0.75 | 0.8 |
| Indoor Unit Cover (M5) | 2.0 | 2.0 | 0.9 | 0.6 | 0.8 | 1.0 |
| Outdoor Unit Cover (M5) | 3.0 | 3.0 | 0.9 | 0.6 | 0.8 | 0.95 |
Results:
The graph of figure 3 shows us that we can produce less waste using a rapid product life cycle strategy. However, it is worth mentioning several considerations of importance which have not been taken into consideration for reason of simplicity can affect the outcome of this result. These considerations include technological progress, failure rate, and whether a and b remain constant thoughout the take back-periods in rapid product life cycle.
Conclusion:
Although Sakamoto shows clearly that rapid product life cycle is a good strategy for keeping certain products' quality requirements high, it is not clear whether rapid product life cycle is necessarily better for the environment. Further studies need to look into more specific assumptions in defining both a and b with cost considerations along with others mentioned in the discussion of the results of this study. Until then different manipulation of the data in this study can produce a wide range of results.
References:
[1] T. Tomiyama, et al, "Disassembly and Recycling of Durable and Consumer Goods in Japan" 6th International Seminar on Life Cycle Engineering, Ontario, Canada June 1999.
[2] F. Kimura "Life Cycle Design For Inverse Manufacturing" EcoDesign 99, First International Symposium on Environmentally Conscious Design and Inverse Manufacturing, Tokyo, Japan, February, 1999.
[3] Hata T., Sakamoto H., Kato S., Kimura F., Suzuki H., "Feasibility Study for 'Rapid Product Life Cycle'" 5th International Seminar on Life Cycle Engineering, KTH Stockholm, Sweden September 1998.
[4] T. Nishi, T. Ohashi, Y. Hiroshige, M. Hirano, and K. Ueno "Study on TV Recyclability" EcoDesign 99, First International Symposium on Environmentally Conscious Design and Inverse Manufacturing, Tokyo, Japan, February, 1999.