Sustainable Integrated Process Planning and Scheduling Optimization Using a Genetic Algorithm with an Integrated Chromosome Representation

Hyun Lee,Chunghun Ha

doi:10.3390/su11020502

Abstract

This paper proposes a genetic algorithm (GA) to find the pseudo-optimum of integrated process planning and scheduling (IPPS) problems. IPPS is a combinatorial optimization problem of the NP-complete class that aims to solve both process planning and scheduling simultaneously. The complexity of IPPS is very high because it reflects various flexibilities and constraints under flexible manufacturing environments. To cope with it, existing metaheuristics for IPPS have excluded some flexibilities and constraints from consideration or have built a complex structured algorithm. Particularly, GAs have been forced to construct multiple chromosomes to account for various flexibilities, which complicates algorithm procedures and degrades performance. The proposed new integrated chromosome representation makes it possible to incorporate various flexibilities into a single string. This enables the adaptation of a simple and typical GA procedure and previously developed genetic operators. Experiments on a set of benchmark problems showed that the proposed GA improved makespan by an average of 17% against the recently developed metaheuristics for IPPS in much shorter computation times.

Highlights

A flexible manufacturing system (FMS) is aimed at automated manufacturing by connecting general-purpose facilities such as numerical control machines and machining centers via computer networks and automated logistics systems [1]
We propose a standard genetic algorithm (GA) for solving integrated process planning and scheduling (IPPS), considering tool flexibility and tool-related constraints
The IPPST we considered is close to realistic manufacturing environments by including the capacity of machines and tools as constraints, which has not been covered by conventional IPPS

Summary

Introduction

A flexible manufacturing system (FMS) is aimed at automated manufacturing by connecting general-purpose facilities such as numerical control machines and machining centers via computer networks and automated logistics systems [1]. The improved flexibility and efficiency of an FMS can allow it to respond rapidly to changes in customer requirements and uncertainties of the manufacturing environments. Process planning is the process of selecting an appropriate process route, machine, tool, and fixtures and jigs for manufacturing a product (part or job). The part information and specifications, such as shape, materials, and tolerances, must be considered to ensure feasibility and to increase manufacturing efficiency. Scheduling is the process of determining the temporal schedule of operations to be implemented on each machine so that the entire operation can be performed efficiently with specified manufacturing resources. Process planning and scheduling are the most vital parts of production planning, and their importance is increasing in FMSes due to enhanced flexibility [2]

Methods

Results

Discussion

Conclusion