| Summary: | Wafer fabrication is a front-end semiconductor manufacturing. Notoriously
complex, it has attracted voluminous researchers to improve its production planning
and control. This study is a fundamental research with the aim to obtain greater
understanding of the basic aspects of conwip-based systems in the wafer
fabrication environment. This comparison was achieved by five production control
systems in a manufacturing environment emulating the complexity of wafer
fabrication. These include push, constant work-in-process (conwip) and modified
conwip systems (conload, m-conwip and nested conwip). Except nested
conwip, the other systems are methods established in different industries. Nested
conwip is a newly conceived method in this research to allow early release of
complementary cards to influence job selection. Characteristics of interest relevant
to wafer fabrication are the re-entrant process flow, job dependent setup, job mix,
priority and batching. The performance measures considered are total output (to),
total critical output (tco), average flow time (avgft), standard deviation flow time
(sdft), average waiting time (avgwt) and machine utilization (mutil). The study
was performed by using the discrete event simulation and statistical analysis. The
selection of parameters, variables and performance measures in the simulation was
relatively based on a wafer fabrication case study. For statistical analysis, analysis of
variance (anova) determined the relationship between variables and performance
measures for each system.
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