Abstract
As a result of rapid product development, the product life cycle has become
shorter, and thus the amount of waste from discarded industrial products has
risen dramatically. An awareness of the world s environmental problems has
stimulated researchers to explore the opportunities to reuse, recycle and
remanufacture end-of-life products. Disassembly is a systematic approach to
separating products into components or subassemblies in order to facilitate
recovery of components or materials. However, the full disassembly of a product
tends to be unproductive due to technical and cost constraints and product
conditions after usage. Therefore, selective disassembly has been introduced
as a more practical approach, where only a limited number of disassembly
paths that lead to selected parts with recovering potential are considered.
This research focuses on the development of a selective disassembly
methodology by reversing an assembly sequencing approach. The methodology
uses a step-by-step approach to generate a disassembly sequence diagram.
This involves listing all the parts within the product, generating a liaison diagram
to illustrate part relationships and then establishing precedence rules describing
prerequisite actions for each liaison. This is followed by segregating
disassembly paths that lead to the removal of selected parts or subassemblies.
Then a winnowing process is applied to these paths to eliminate invalid
disassembly states and transitions. The last step is to select the optimal
disassembly path by using the time requirement as the main selection criterion.
In order to shorten the time for carrying out the sequencing process, a javabased
program that is capable of performing the first three steps has been
created. The program requires three basic inputs in forms of precedence rules,
and user-required part (s) and disassembly rules, prescribing which liaison (s)
should be done subsequent to a particular liaison. The viability of the
methodology and the program is proved through seven case studies conducted
on a fishing reel, a single-hole punch, a kettle, an entire washing machine and
three washing machine subassemblies. The application of the program allows the users to determine an optimal disassembly sequence in a very short time
and with only basic product information as the input.