Abstract
This study numerically investigates the effects of a moving crane and airflow on contaminant removal efficiency of various reticle box coverage sequences in a stocker. The analyzed characteristics of flow patterns are used to protect the reticles from contaminants, without altering their internal component configuration in conjunction with the aim of cost-savings. A finite volume method was applied in a numerical analysis using computational fluid dynamics software, ANSYS Fluent. To simulate actual operating conditions, the effects of inlet velocity of clean air and crane movement speed on contaminant removal efficiency (CRE) are considered, and a particle release technique is analyzed to determine contaminant concentrations in the stocker. The results show that a higher airflow rate leads to a better contaminant removal efficiency in the stocker. For the various arrangements of reticle boxes in the stocker, the symmetric coverage sequence provides the most satisfactory contaminant removal rate. An optimal inlet airflow velocity of 0.12 m/s is obtained based on the CRE distribution. In addition, the airflow distributions indicate that a vortex is induced by the air flow through a solid boundary; thus, a higher inlet airflow velocity results in a small vortex that also benefits the CRE. The results also demonstrate that a high crane movement speed causes a large reverse flow region at the bottom that also induces a long wake behind the crane, into which particles are easily drawn.
Highlights
In recent years, the high-tech manufacturing industry has been overwhelmed by the rapid advances in technology
The results showed that the downwash airflow could prevent the formation of a recirculation zone behind the automatic guided vehicle (AGV) as it moved with accelerated, decelerated, and constant velocities
Lin et al [11] investigated the flow patterns on maintaining the air quality for a thin-film-transistor liquid-crystal-display (TFT-LCD) panel delivery facility in a clean room. They reported that increasing the air velocity of the fan filter unit (FFU) can enhance the contaminant removal performance and suggested the moving velocity of the delivery facility should be at 0.16 m/s
Summary
The high-tech manufacturing industry has been overwhelmed by the rapid advances in technology. It is necessary to investigate the characteristics of flow fields inside the stocker based on various moving crane speeds and inlet velocities of clean air. Lin et al [11] investigated the flow patterns on maintaining the air quality for a thin-film-transistor liquid-crystal-display (TFT-LCD) panel delivery facility in a clean room They reported that increasing the air velocity of the FFU can enhance the contaminant removal performance and suggested the moving velocity of the delivery facility should be at 0.16 m/s. The detailed characteristics of a flow field and particle transport induced by the interaction between downwash air flow and a moving object in mini-environments was studied by Tsao et al [15] with the help of experiments. A numerical simulation is used to analyze the unsteady flow fields of a stocker with a moving crane (at different speeds) in a clean room. The characteristics of reticle stocker flow fields and the particle distributions are investigated under different conditions
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