Job sequencing and layout optimization in virtual production line

Most of the problems involving the design and planning of manufacturing systems are combinatorial and NP-hard. It covers all aspect of creating and operating a manufacturing system before it is implemented. The main activities in creating and operating a manufacturing system are determining the job size, resources needed, equipment layout, routing sequence, and process scheduling. This problem must be solved before it is implemented in real factory. A new trend is using virtual factory approach for testing and validating the proposed design and planning. Designer will have feel at the factory while doing layout planning and design. The contribution of this paper is the integration of two optimization models such as: layout and sequence (job) optimization to those factories who want to produce the various kinds of products with fixed and changeable machine locations as integrated approach for designing a virtual production line. Due to the combinatorial nature of the solution spaces, genetic algorithm is applied for both sequencing and layout. A case study is also reported to demonstrate the feasibility of the proposed approach

Reentrant FMS scheduling in loop layout with consideration of multi loading-unloading stations and shortcuts

The scheduling problem in flexible manufacturing systems (FMS) environment with loop layout configuration has been shown to be a NP-hard problem. Moreover, the improvement and modification of the loop layout add to the difficulties in the production planning stage. The introduction of multi loading-unloading points and turntable shortcut resulted on more possible routes, thus increasing the complexity. This research addressed the reentrant FMS scheduling problem where jobs are allowed to reenter the system and revisit particular machines. The problem is to determine the optimal sequence of the jobs as well as the routing options. A modified genetic algorithm (GA) was proposed to generate the feasible solutions. The crowding distance-based substitution was incorporated to maintain the diversity of the population. A set of test was applied to compare the performance of the proposed approach with other methods. Further computational experiments were conducted to assess the significance of multi loading-unloading and shortcuts in reducing the makespan, mean flow time, and tardiness. The results highlighted that the proposed model was robust and effective in the scheduling problem for both small and large size problems

Empirical evidence of AMT practices and sustainable environmental initiatives in Malaysian automotive SMEs

This paper presents significant empirical evidence on the relationship between Advanced Manufacturing Technology (AMT) practices and sustainable environmental initiatives with the manufacturing capabilities of automotive SMEs in Malaysia. A cross-sectional survey is adopted in this study, which involves 83 Malaysian automotive SMEs. Two hypotheses are proposed in this study, i.e. Hypothesis 1: There are positive effects of AMT practices on the manufacturing capabilities of SMEs and Hypothesis 2: There are positive effects of sustainable environmental initiatives on the manufacturing capabilities of SMEs. The results obtained from the pairwise correlation analysis indicate that both AMT practices and sustainable environmental initiatives have positive effects on manufacturing capabilities, which support both hypotheses. In addition, it is found that 50% of the SMEs implement AMT for flexibility and cost reduction in the past five years. It is also found that more than 80% sustainable practices are adopted in most of the SMEs with the exception of Life Cycle Assessment. Based on the findings, there is a need to move forward into the hybrid approach, which will consider both AMT practices and environmental initiatives to ensure that SMEs remain competitive and become the world player in the automotive industry

Reentrant FMS scheduling in loop layout with consideration of multi loading-unloading stations and shortcuts

This article is closed access.The scheduling problem in flexible manufacturing systems (FMS) environment with loop layout configuration has been shown to be a NP-hard problem. Moreover, the improvement and modification of the loop layout add to the difficulties in the production planning stage. The introduction of multi loading-unloading points and turntable shortcut resulted on more possible routes, thus increasing the complexity. This research addressed the reentrant FMS scheduling problem where jobs are allowed to reenter the system and revisit particular machines. The problem is to determine the optimal sequence of the jobs as well as the routing options. A modified genetic algorithm (GA) was proposed to generate the feasible solutions. The crowding distance-based substitution was incorporated to maintain the diversity of the population. A set of test was applied to compare the performance of the proposed approach with other methods. Further computational experiments were conducted to assess the significance of multi loading-unloading and shortcuts in reducing the makespan, mean flow time, and tardiness. The results highlighted that the proposed model was robust and effective in the scheduling problem for both small and large size problems