• Design & Manufacturing
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• v.9 no.2
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• pp.25-29
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• 2015

This paper presented characterization of spray velocity and angle of spray nozzle systems for cosmetic products. Diameter and length of nozzle orifice were chosen as shape factors of the spray system. Spray orifice of the spray pattern is a factor influencing the quality of the product. Fluid analysis was conducted by using "Fluent" to obtain spray angle and velocity. RSM (Response Surface Method) was used to approximate the relationship between these 2 factors and spray characteristics. To evaluate the proposed method, experimental work with existing was conducted and good agreement between simulation and experimental results.

• Design & Manufacturing
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• v.13 no.3
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• pp.41-47
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• 2019

In conventional machining, the use of cutting fluid is essential to reduce cutting heat and to improve machining quality. However, to increase the performance of cutting fluids, various chemical components have been added. However, these chemical components during machining have a negative impact on the health of workers and cutting environment. In current machining, environment-friendly machining is conducted using MQL (minimum quantity lubrication) or cryogenic air spraying to minimize the harmful effects. In this study, the injection nozzle that can combined injecting minimum quantity lubrication(MQL) and cryogenic gas was designed and the shape optimization was performed by using computational fluid dynamics(CFD) and design of experiment(DOE). Performance verification was performed for the designed nozzle. The diameter of the sprayed fluid at a distance of 30 mm from the nozzle was analyzed to be 21 mm. It was also analyzed to lower the aerosol temperature to about 260~270K.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.462-473
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• 2019

The effects of the location and dimension of the gate, location, and volume of the feeder, application of a chill, chill volume, and heating method of the feeder with respect to the effect of the mold-designing technologies on the defect status of the products are described. It is possible to increase the solidification time of the feeder by heating feeder. Furthermore, the pressure generated from the feeder is imposed on a product, and this decreases the generation of shrinkage porosities. In this study, two types of gating and feeding systems had been proposed: the bottom L-type junctions and the top L-type junctions. Additionally, solidification behaviors, such as solidification time, shrinkage porosities, weight percentage of chill system to product, hot spot, and solidification time ratio (=Solidification time of feeder/solidification time of product), are extensively analyzed by using commercial casting simulation software. Based on the solidification behaviors, reasonable mold design, feeding system, critical feeder heating temperature, and solidification time ratios are proposed in the sand casting process for the fabrication of carrier housing in order to reduce the casting defects and to increase the recovery rate.

• Design & Manufacturing
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• v.15 no.1
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• pp.14-20
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• 2021

The objective of this study is to introduce the new possibility of sensing technology based on inductive displacement sensors to monitor the status of wheel position in the hot forging process. In order to validate effectiveness of proposed sensing technology, the indirect forging force measurement with displacement sensor was applied into a typical closed hot forging die-set used for the manufacturing of flange bolts. The locations to implement the displacement sensor were selected carefully by simulating forming process and static structural. From the measurement results of the forging force change during one hot forging cycle, it was found that the proposed monitoring system can provide useful information to understand the detailed behaviors of die-set in the closed hot forging process.

• Design & Manufacturing
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• v.15 no.4
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• pp.37-42
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• 2021

The tube necking process increases the thickness of the material, and some of the tube necking products require cutting on the inside of the formed product as a post-process. In order to prevent over-cutting or un-cutting due to increased thickness during cutting, it is necessary to know in advance the increase in thickness after forming. Therefore, in this study, the thickness change according to the tube necking was observed. Aluminum 3003-F and 6061-O were used for the materials used in the experiment, and necking was carried out up to 50% of the outer diameter of the tube through five processes. The two materials were formed under the same conditions, and the thickness of three points was observed in each process. In addition, the thickness increase of the two materials was compared, and the trend of thickness increase according to the cumulative necking ratio was observed. As a result of the experiment, both materials had the smallest thickness at the end of the formed product. In addition, as a result of comparing the thickness measurement values of the two materials, the maximum difference was 0.1mm, indicating that there was no difference in thickness between the two materials.

• Journal of Korean Society for Quality Management
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• v.51 no.4
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• pp.735-749
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• 2023

Purpose: The purpose of this study is to derive solutions and prevent similar cases from occurring by analyzing the causes of cracks found in temperature cycling tests of rocket motor. Methods: By combining the results of the current state confirmation test, non-destructive test, domestic and foreign rocket motor comparison test, cutting test, and adhesion test according to the number of times to apply mold release agent, a Cause and Effect Diagram analysis was performed to derive the cause of cracks. Results: Through this study, 26 factors that could cause cracking in rocket motors during temperature cycling tests were identified. Through various additional test results, a total of five causes were identified, including chemical and structural design of the joint between the propellant and stress relief insert, omission of procedure in the manufacturing procedures, natural aging due to temperature, and load accumulation due to temperature changes. The fundamental cause was confirmed to be insufficient consideration of the release properties of the propellant and stress relief insert. Conclusion: During the design process, it was confirmed that this could be solved by structurally or chemically designing the insert so that it does not combine with the propellant, or by applying a mold release agent during the manufacturing process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.321-322
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.429-430
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• 2009

• Transactions of Materials Processing
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• v.14 no.2 s.74
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• pp.112-120
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• 2005

In the die casting process, the flow of liquid metal has significant influence on the quality of casting products and die life. For the optimal process design of gear housing of automobile transmission, various analyses were performed in this study by using computer simulation code, MAGMAsoft. The simulation has been focused on the molten metal behaviors during the mold filling and solidification stages for the sound casting products. Also internal defects were predicted by application of air pressure and feeding criteria.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.477-480
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• 1995

Dccisions of optimal filling conditions for the chip encapsulation have been done primarily by an ad hoc use of expertise accumulated over the years because the chip encapsulation process is quite complicated. The current CAE systems do not provide mold designers with necessary knowledge of the chip encapsulation for the successful design of optimal filling except flow simulation capability. There have been no attempts to solve the optimal filling problem in the process of the chip encapsulation. In this paper, we have constructed an design system for optimal filling to avoid short shot in the chip encapsulation process which combines an optimization methodology with CAE software.