Industrial recycling and remanufacturing is practice of growing importance due to the increasing environmental and economic pressures. It involves product disassembly to retrieve the desired parts and/or subassemblies by separating a product into its constituencies. The disassembly process modeling and planning is more challenging than assembly since its termination goal is not necessarily fixed depending on the system status. Moreover, it is uncontested that disassembly is charged with more uncertainty in system structures and component conditions than assembly. The paper reviews methods for modeling and process planning in disassembly. Its purpose is to survey the state-of-the-art of this emerging area to supply important information for future study.

This paper presents a methodology for designing and implementing disassembly plans and processes using Petri nets (PN) for remanufacturing obsolete products. Process modeling and planning using PN are discussed. The proposed PN accommodate product topology and precedence relations during disassembly. Decision values are attached to PN to enable consideration of uncertainty during process execution. The resulting planner guarantees the plan's optimality when product remanufacturing parameters are known. In cases of uncertainty about product parameters, an adaptation scheme is designed and implemented to facilitate the goal of maximum benefit. Three planning and execution algorithms (globally fixed, limited adaptive, adaptive) are presented for disassembly processes. They are demonstrated comprehensively through a robotic disassembly system, and its use is demonstrated in disassembly of a car radio.

A principal process during the remanufacturing of worn-out or malfunctioning products is disassembly that enables the dumping, cleaning, repair or replacement of components as desired. Products subjected to disassembly exhibit uncertainty in the product structure and component conditions. Hence the termination goal (the level of disassembly) is subject to change, and the disassembly plan must be adapted. This paper proposes a mathematically sound disassembly Petri net (DPN) for the modeling and adaptive planning of disassembly processes. The planning algorithm guarantees the optimal remanufacturing value when each node's utility function (benefit of a subassembly or part and cost of a disassembly operation) is fixed. It can be modified to deal with the cases when the disassembly operation success rates vary with the product condition and reliability of resources performing the operations. The proposed methodology and algorithms are demonstrated through the sample disassembly of a telephone.