Causes of the Gloss Transition Defect on High-Gloss Injection-Molded Surfaces

Gim, Jinsu; Han, Eun Su; Rhee, Byong-Duk; Friesenbichler, Walter; Gruber, Dieter P.

doi:10.3390/polym12092100

Cited by 9 publications

(7 citation statements)

References 34 publications

(68 reference statements)

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“…The packing pressure and time of the packing stage were expected to be the most influential factors on the part weight because the packing stage compensates for shrinkage of the polymer material. However, the injection speed was expected to be less influential than the packing pressure and time because the filling stage predominantly affects the surface quality, not shrinkage in the packing and cooling stages [ 34 ]. These are common process parameters that are tuned to optimize the injection-molding process.…”

Section: Methodsmentioning

confidence: 99%

Novel Analysis Methodology of Cavity Pressure Profiles in Injection-Molding Processes Using Interpretation of Machine Learning Model

Gim

Rhee

2021

Polymers

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The cavity pressure profile representing the effective molding condition in a cavity is closely related to part quality. Analysis of the effect of the cavity pressure profile on quality requires prior knowledge and understanding of the injection-molding process and polymer materials. In this work, an analysis methodology to examine the effect of the cavity pressure profile on part quality is proposed. The methodology uses the interpretation of a neural network as a metamodel representing the relationship between the cavity pressure profile and the part weight as a quality index. The process state points (PSPs) extracted from the cavity pressure profile were used as the input features of the model. The overall impact of the features on the part weight and the contribution of them on a specific sample clarify the influence of the cavity pressure profile on the part weight. The effect of the process parameters on the part weight and the PSPs supported the validity of the methodology. The influential features and impacts analyzed using this methodology can be employed to set the target points and bounds of the monitoring window, and the contribution of each feature can be used to optimize the injection-molding process.

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Section: Methodsmentioning

confidence: 99%

Novel Analysis Methodology of Cavity Pressure Profiles in Injection-Molding Processes Using Interpretation of Machine Learning Model

Gim

Rhee

2021

Polymers

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“…The difference between the cooling times used did not cause a visible difference in the filling. Gim et al also concluded the fact that the higher injection speed could add more melt into the microstructures before the maximum cavity pressure was reached [ 9 ]. This was due to an increased injection rate, leading to a decrease in melt viscosity that improves the melt flow in microstructures.…”

Section: Methodsmentioning

confidence: 99%

“…The replication quality of molded parts or even their mechanical properties can be improved by optimizing process parameters and controlling material flow. Therefore, an optimization approach has been used to improve the mechanical properties of the molded part made by polypropylene (PP) [ 4 , 8 , 9 , 10 , 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Femtosecond-Laser-Structured Injection Molding Tool on Mechanical Properties of the Manufactured Product

Kun

Weltsch

2021

Polymers

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During the injection molding process, the melt travels with a flow due to friction. As the velocity of the layers next to the wall is less than that of those flowing in the middle of the channel, a fountain flow is formed at the melt front. The temperature of the polymer surface decreases from the melt temperature to the contact temperature after contacting the mold surface. Based on all this, a complex shell–core structure is formed in injection-molded products, which can be influenced by the processing parameters and the surface of the tool insert. This paper focuses on investigating the effect of the microstructures replicated from the insert to the polymer product on its mechanical properties. During the research, two microstructured surfaces were created, with different effects on the melt flow formed by the femtosecond laser. These were compared with a ground insert to analyze the effects. For examining the effect of technological variables on the mechanical properties, an experimental design was used. The structure created by the femtosecond laser on the surface of the tool influenced the mechanical properties of the polymer products. Recognizing the effect of microstructures on the melt front and, through this, the change in mechanical properties, a predefined polymer product property can be achieved.

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“…This can be also used to minimize the reduction in tensile strength in parts, where weld lines are present [ 21 , 22 , 23 ]. Besides, the high cavity surface temperature is commonly used to improve surface quality (removal of weld lines’ presence, obtaining high-gloss surface, better replication of microstructure of the cavity surface) [ 6 , 11 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Application of Magnetic Concentrator for Improvement in Rapid Temperature Cycling Technology

2020

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The main method to improve the filling of the cavity by the polymer melt is to increase the mold temperature. Rapid temperature cycling (RTC) technologies have been used around the world for several years, improving the quality of injection molded parts with a slight extension of production time. The present work focuses on the application of induction heating technology in the injection molding process since it is the most effective and most intensively developing method of heating in modern RTC technologies. In this research, the application of the induction heating process for selected surfaces was investigated with particular emphasis on the dynamics of the process. The numerical simulations were used to study the influence of the number of coils, the distance between coils and cavity surface and the mold material was examined with and without the presence of a magnetic concentrator. According to the obtained results, several crucial conclusions were made: the efficiency of heating is directly correlated with the distance between the inductor and the mold surface, the presence of magnetic flux concentrator significantly improves the homogeneity of temperature distribution and heating efficiency, application of aluminum mold lowers the obtained surface temperature.

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Causes of the Gloss Transition Defect on High-Gloss Injection-Molded Surfaces

Cited by 9 publications

References 34 publications

Novel Analysis Methodology of Cavity Pressure Profiles in Injection-Molding Processes Using Interpretation of Machine Learning Model

Novel Analysis Methodology of Cavity Pressure Profiles in Injection-Molding Processes Using Interpretation of Machine Learning Model

Effect of Femtosecond-Laser-Structured Injection Molding Tool on Mechanical Properties of the Manufactured Product

Application of Magnetic Concentrator for Improvement in Rapid Temperature Cycling Technology

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