A switching rule for plastics identification in electronics recycling

Abstract

The looming obsolescence of 3 billion consumer electronics by 2010 calls for effective recycling of 10 billion pounds of high-value engineering thermoplastics. Because general shredding operations generate mixed plastics of low value, a switching rule is needed rapidly to identify plastics for sortation by colour and type to increase plastics-to-plastics recycling value. The current paper develops a heuristic rule to determine the thresholds for a switching rule that reduces set-up time while managing queue space. Our recycling system is modelled as a multiclass queuing network in a simulation model. Results indicate that laser identification probe utilization, setups, and queue space are sensitive to the switching rule. Our work contributes important insights into the relationship between traffic intensity, setup time, and queue capacity, and generalizes to multiclass queuing systems in other applications.

Keywords:

• Multiclass queuing network
• Scheduling
• Switching rules
• Plastics identification
• Electronics recycling

Acknowledgements

The authors are grateful to two anonymous reviewers for their helpful comments on an earlier version of this paper. The authors thank Winston Bonawi-tan, Lisa Tieman, Leslie Blyler and Michelle Madden for their assistance in collecting data for the electronics recycling process. Author Wieland was supported by an Eastman Kodak Fellowship from the Center for Collaborative Manufacturing at Purdue University. This material is based upon work supported by the National Science Foundation under Grants No. DMII-0049074 and BES-0124761. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.