Solving a mathematical model integrating unequal-area facilities layout and part scheduling in a cellular...

Area of Science:

• Operations Research
• Industrial Engineering
• Manufacturing Systems

Background:

• Cellular Manufacturing Systems (CMS) design often separates machine layout and part scheduling.
• This separation can lead to suboptimal performance and increased operational costs.

Purpose of the Study:

• To develop a novel integrated mixed-integer nonlinear programming model for CMS design.
• To simultaneously consider machine layout and part scheduling as interrelated decisions.
• To minimize makespan, tardiness penalties, and material handling costs.

Main Methods:

• Formulation of an integrated CMS model incorporating part due date, material handling time, operation sequence, processing time, unequal-area facilities, and part scheduling.
• Investigation of sequential versus concurrent approaches for design.
• Development of an efficient genetic algorithm (GA) to address the NP-hard nature of the integrated model.
• Comparison with Branch and Bound (B&B) methods.

Main Results:

• The concurrent approach significantly improves upon sequential design methods.
• The developed GA outperforms B&B in finding optimal solutions faster for both sequential and concurrent approaches.
• Objective function value improvements averaged around 17% with GA and 14% with B&B using the concurrent approach.

Conclusions:

• Integrating machine layout and part scheduling in CMS design yields substantial performance improvements.
• The proposed integrated model and GA offer an efficient solution for complex CMS design problems.
• Concurrent design is superior to sequential design for optimizing CMS performance.