• Design & Manufacturing
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• v.9 no.3
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• pp.1-8
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• 2015

This study presents the preform injection molding and the blow molding of the injection stretch-blow molding process for PET bottles. The numerical analysis of the injection molding and the blow molding of a preform is considered in this paper using CAE with a view to minimize the warpage and the thickness. In order to determine the design parameters and processing conditions in injection/blow molding, it is very important to establish the numerical model with physical phenomenon. In this study, we appropriately predicted the warpage, deformation and thickness distribution along the product walls.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1834-1839
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• 2003

Temperature and velocity distributions of hot air flows in rotational molding machines with two different shapes and structures of oven and inlet were investigated by using FLUENT, a commercial computational fluid dynamics code. The shape and structure of oven and inlet in current rotational molding machine were improved. Two different sizes of mold inside each oven were considered in the analysis. Temperature and velocity distributions of hot air flows in two different rotational molding machines were compared to each other. In order to reduce cycle time and improve product quality in current rotational molding machine, the improved shape and structure of oven and inlet were proposed.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.103-109
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• 2008

The sink mark on boss parts is generated by the volumetric shrinkage that is caused by both the molding thickness and the boss wall thickness. The volumetric shrinkage is caused by packing pressure and its amount tends to decrease by increasing the packing pressure. The packing pressure can therefore increase the flow rate to a boss part and causes the depth of sink mark to increase. As the molding thickness and the boss wall thickness in the boss part can increase the part volume, these may yield bad solidifying and also extend the molding cycle. In this paper, both the injection molding test and the flow analysis were carried out to investigate the effect of sink mark that was generated in the boss wall thickness of injection molded products. The sink mark could also be caused by thickness ratio of boss part. For a given thickness ratio of boss, several molding process parameters such as packing pressure, packing time and melt temperature, affecting to generation of the sink mark were discussed

• Design & Manufacturing
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• v.2 no.3
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• pp.22-27
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• 2008

Forming of PET bottle was performed by injection-stretch blow molding. Blow molding is process of contacting the dies with air of materials by pressing. In this paper, the aim was to improve reliability of technical stabilization for the PET bottle that is last productive product and process technology which was able to do maximization by a preform performance enhancement of the uniform thickness that took temperature and a characteristic of materials. Preform design and dies manufacture were conducted using injection blow molding analysis results. Therefore thickness error of 5% for PET bottle can be obtained in this paper.

• Design & Manufacturing
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• v.17 no.3
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• pp.1-7
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• 2023

Blow molding is a manufacturing process in which thermoplastic preforms are preheated and then pneumatically expanded within a mold to produce hollow products of various shapes. The two-step process, a type of blow molding method, requires the output of multiple infrared lamps to be adjusted individually, so the process of finding initial conditions hinders productivity. In this study, digital twin technology was applied to solve this problem. A blow molding simulation technique was established and simulation-based metadata was generated. A response surface ROM (Reduced Order Model) was built using the generated metadata. Then, a dynamic ROM was constructed using the results of 3D heat transfer analysis. Through this, users can quickly check the product wall thickness uniformity according to changes in the control value of the heating lamp for products of various shapes, and at the same time, check the temperature distribution of the preform in real time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.63-68
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• 2017

The purpose of this study is to improve the whitening phenomenon around the PET preform gate for blow molding. CAE analysis of plastic injection molding has been applied to design of preform shape and select the injection molding conditions. A ceramic insulation gate with lower thermal conductivity than metal is applied to improve the whitening phenomenon created around the gate in the injection molding process. According to the results of CAE analysis, the warpage deformation at the square corner was estimated to be about 0.34 mm at the bottom. From the results of the temperature history analysis, it was confirmed that the resin near the gate cooled more rapidly than the cavity. Ceramic insulated gates were fabricated to reduce the cooling rate and experiments were conducted to confirm the effectiveness of the whitening phenomenon improvement. As a result of the ceramic insulation gate experiment, it was confirmed that the whitening phenomenon was significantly reduced around the gate.

• Korea-Australia Rheology Journal
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• v.20 no.2
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• pp.79-88
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• 2008

In this study, we focus on the improvement of the filling efficiency in injection molding by application of ultrasonic vibration. While studies about the filling efficiency of typical filling processes in the injection molding have been widely performed, there have been only few studies about the filling efficiency of an ultrasonic process. The effect of the ultrasonic vibration is an important process condition, which influences the flow characteristics of polymer melt. This new condition even affects well-known injection conditions such as cavity pressure, injection temperature and mold temperature. For this study, we carried out a numerical analysis by appropriate modeling and analysis of the ultrasonic process in the filling process. To verify this numerical analysis, we compared the numerical results with the experimental data. Also, we analyzed the filling process in a thin cavity using this numerical analysis. To understand the flow characteristics of polymer melt in the ultrasonic process, we substituted real and complex vibration conditions with simplified and classified conditions according to the position of vibrating cavity surfaces and the phase difference between two opposing cavity surfaces. We also introduced MFR (melt flow ratio) as a new index to estimate the filling efficiency in the ultrasonic process.

• Journal of Power System Engineering
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• v.21 no.3
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• pp.37-44
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• 2017

In this study, failure analysis of the angular pin for molding machines to aluminum component molding was carried out. SM45C steel was used for the angular pin, it was surface hardened by the induction surface hardening heat treatment. The cross section of damaged angular pin was observed, and micro Vickers hardness value from the fractured part was measured. Brittle fracture was occurred from the fracture surface of angular pin, therefore, impact toughness value was evaluated by V-notch Charpy impact test. It was confirmed that the impact absorption energy was high when was tempered at a high temperature for a long time, and the toughness was slightly increased. Also, 2-parameter Weibull statistical analysis was investigated in order to evaluate the reliability of the measured micro Vickers hardness values and absorbed energy. The micro Vickers hardness and absorbed energy well followed a two-parameter Weibull probability distribution, respectively. The reverse design against angular pin was proposed as possible by using test results.

• Transactions of Materials Processing
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• v.16 no.1 s.91
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• pp.25-30
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• 2007

The present study covers an integrated simulation method to evaluate optical performance of an aspheric plastic lens by connecting a finite element (FE) analysis of injection molding with a ray tracing simulation. Traditional ray tracing methods have based on the assumption that the optical properties of a lens are homogeneous throughout the entire volume. This assumption is to a certain extent unrealistic for injection-molded plastic lenses because material properties vary at every point due to the injection molding effects. To take into account the effects of the inhomogeneous optical properties of the molded lens, a new.ay tracing scheme is proposed in conjunction with a FE analysis of the injection molding. A numerical scheme is developed to calculate ray paths on every element layer with more realistic information of the refractive indices which can be obtained through the FE analysis. This information is then used to calculate the ray paths based on the FE mesh of which nodal points have unique index values. The proposed tracing scheme is implemented on the tracing of an aspheric lens, and its validity is ascertained through experimental verification.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.388-395
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• 2015

The waste gate valve (WGV) for gasoline vehicles operate in a harsh high-temperature environment. Hence, WGVs are typically made of Inconel 713C, which is a type of Ni-based superalloy. Recently, the metal injection molding (MIM) process has attracted considerable attention for parts used under high-temperature conditions. In this study, an MIM analysis for the head and other parts of the WGV is conducted using a commercial CAE program Moldflow. Further, optimal manufacturing conditions are determined by analyzing flow characteristics at various injection times and locations. Moreover, to improve the accuracy of the analysis results, we compare the actual temperature of the mold during injection processing with that observed through the analysis. As the results, metal injection patterns of analysis are well in accord with these of short shot test. And the temperature variations of analysis is also very similar with those of feedstock when metal injection molding.