Parametric Study for Runner Modifications of Die Casted Part with Venting Systems

High-pressure die casting (HPDC) is a process used for creating complex components by injecting the molten metal inside the cavity at high pressure. Failure in die casting may reduce product mechanical properties, surface quality, and life cycle. In this paper, the die-casting process of an inspection instrument – test piece is investigated for parametric study and Computational fluid dynamics (CFD) analysis. Parameters used in the die-casting process are important since it affects the molten flow quality inside the cavity. Thus, a parametric study is done to investigate the optimum parameter use in the die-casting process of the test piece. Runner gating system design is also one of the important criteria to maintain the quality of products. This paper also investigated the effect of runner gating system design optimization in reducing gas porosity. The CT scan of the sample mold is included to compare the relationships between gas porosity occurrence with CFD results. This paper proposed a new runner design named outward curvature runner with an air vent that can improve velocity and temperature distributions in reducing die-casting defects. In addition to that, air vents are installed to extend the volume and promote higher suction, to eliminate gas bubbles entrapment inside the cavity

Parametric Study for Runner Modifications of Die Casted Part with Venting Systems

High-pressure die casting (HPDC) is a process used for creating complex components by injecting the molten metal inside the cavity at high pressure. Failure in die casting may reduce product mechanical properties, surface quality, and life cycle. In this paper, the die-casting process of an inspection instrument – test piece is investigated for parametric study and Computational fluid dynamics (CFD) analysis. Parameters used in the die-casting process are important since it affects the molten flow quality inside the cavity. Thus, a parametric study is done to investigate the optimum parameter use in the die-casting process of the test piece. Runner gating system design is also one of the important criteria to maintain the quality of products. This paper also investigated the effect of runner gating system design optimization in reducing gas porosity. The CT scan of the sample mold is included to compare the relationships between gas porosity occurrence with CFD results. This paper proposed a new runner design named outward curvature runner with an air vent that can improve velocity and temperature distributions in reducing die-casting defects. In addition to that, air vents are installed to extend the volume and promote higher suction, to eliminate gas bubbles entrapment inside the cavity

Analysis of Fractures and Microstructures on Different Injection Speeds in High-Pressure Die-Casting Magnesium Alloy

In this study, to clarify the unknown physical properties of the Mg-Al-Th-RE alloy, the relationship between the injection conditions and the internal porosities, and the mechanical properties exerted by the solidification microstructure was investigated. The obtained cast samples were investigated using X-ray CT internal measurements, tensile tests, Vickers hardness tests, and solidification microstructure observations. The tensile strength and the elongation at the injection speed of 5.0 m/s were higher than at 2.0 m/s. The number of porosities affected the tensile strength and the elongation even at the same fracture position. In addition, it was confirmed that segregation affected the destruction smaller the porosity size and the greater the variability of porosity. As the injection speed increased, the amount of heat transferred between the molten metal and the wall surface also increased, resulting in quick freezing and solidification. The tensile strength increased at the injection speed of 5.0 m/s because the interface between the scattered primary crystals and eutectic systems was narrow. On the other hand, at the injection speed of 2.0 m/s, the tensile strength decreased because the molten metal was delayed in solidification and dendrite growth became remarkable

Analysis of Fractures and Microstructures on Different Injection Speeds in High-Pressure Die-Casting Magnesium Alloy

In this study, to clarify the unknown physical properties of the Mg-Al-Th-RE alloy, the relationship between the injection conditions and the internal porosities, and the mechanical properties exerted by the solidification microstructure was investigated. The obtained cast samples were investigated using X-ray CT internal measurements, tensile tests, Vickers hardness tests, and solidification microstructure observations. The tensile strength and the elongation at the injection speed of 5.0 m/s were higher than at 2.0 m/s. The number of porosities affected the tensile strength and the elongation even at the same fracture position. In addition, it was confirmed that segregation affected the destruction smaller the porosity size and the greater the variability of porosity. As the injection speed increased, the amount of heat transferred between the molten metal and the wall surface also increased, resulting in quick freezing and solidification. The tensile strength increased at the injection speed of 5.0 m/s because the interface between the scattered primary crystals and eutectic systems was narrow. On the other hand, at the injection speed of 2.0 m/s, the tensile strength decreased because the molten metal was delayed in solidification and dendrite growth became remarkable

Parametric Study for Runner Modifications of Die Casted Part with Venting Systems

High-pressure die casting (HPDC) is a process used for creating complex components by injecting the molten metal inside the cavity at high pressure. Failure in die casting may reduce product mechanical properties, surface quality, and life cycle. In this paper, the die-casting process of an inspection instrument - test piece is investigated for parametric study and Computational fluid dynamics (CFD) analysis. Parameters used in the diecasting process are important since it affects the molten flow quality inside the cavity. Thus, a parametric study is done to investigate the optimum parameter use in the die-casting process of the test piece. Runner gating system design is also one of the important criteria to maintain the quality of products. This paper also investigated the effect of runner gating system design optimization in reducing gas porosity. The CT scan of the sample mold is included to compare the relationships between gas porosity occurrence with CFD results. This paper proposed a new runner design named outward curvature runner with an air vent that can improve velocity and temperature distributions in reducing die-casting defects. In addition to that, air vents are installed to extend the volume and promote higher suction, to eliminate gas bubbles entrapment inside the cavity

EFFECTS OF INJECTION SPEED ON MECHANICAL PROPERTIES IN HIGH-PRESSURE DIE CASTING OF MG-RE ALLOY

In this study, in order to clarify the unknown physical properties of the Mg-Al-Th-RE alloy, the relationship between the injection conditions and the internal porosities and the mechanical properties exerted by the solidification microstructure were investigated. The obtained cast samples were investigated using X-ray CT internal measurements, tensile tests, Vickers hardness tests and solidification microstructure observations. The flow simulation and the X-ray CT analysis results showed that the porosity volume increased as the injection speed increases. The higher injection speed also affected the metal microstructure to become denser, which leads to a higher material strength and hardness. The eutectic phases quickly formed because of the shorter filled and cooled time. Therefore, the growth of the primary phase α-Mg was suppressed. On the other hand, it was considered that the material strength and hardness were greatly reduced by the coarse primary phase

Desenvolvimento de uma ferramenta para identificar regiões codificadoras nos transcritos do fungo Phakopsora pachyrhizi.

WB2016

Analysis of Fractures and Microstructures on Different Injection Speeds in High-Pressure Die-Casting Magnesium Alloy

In this study, to clarify the unknown physical properties of the Mg-Al-Th-RE alloy, the relationship between the injection conditions and the internal porosities, and the mechanical properties exerted by the solidification microstructure was investigated. The obtained cast samples were investigated using X-ray CT internal measurements, tensile tests, Vickers hardness tests, and solidification microstructure observations. The tensile strength and the elongation at the injection speed of 5.0 m/s were higher than at 2.0 m/s. The number of porosities affected the tensile strength and the elongation even at the same fracture position. In addition, it was confirmed that segregation affected the destruction smaller the porosity size and the greater the variability of porosity. As the injection speed increased, the amount of heat transferred between the molten metal and the wall surface also increased, resulting in quick freezing and solidification. The tensile strength increased at the injection speed of 5.0 m/s because the interface between the scattered primary crystals and eutectic systems was narrow. On the other hand, at the injection speed of 2.0 m/s, the tensile strength decreased because the molten metal was delayed in solidification and dendrite growth became remarkable

GATA2 Mediates Thyrotropin-Releasing Hormone-Induced Transcriptional Activation of the Thyrotropin β Gene

Thyrotropin-releasing hormone (TRH) activates not only the secretion of thyrotropin (TSH) but also the transcription of TSHβ and α-glycoprotein (αGSU) subunit genes. TSHβ expression is maintained by two transcription factors, Pit1 and GATA2, and is negatively regulated by thyroid hormone (T3). Our prior studies suggest that the main activator of the TSHβ gene is GATA2, not Pit1 or unliganded T3 receptor (TR). In previous studies on the mechanism of TRH-induced activation of the TSHβ gene, the involvements of Pit1 and TR have been investigated, but the role of GATA2 has not been clarified. Using kidney-derived CV1 cells and pituitary-derived GH3 and TαT1 cells, we demonstrate here that TRH signaling enhances GATA2-dependent activation of the TSHβ promoter and that TRH-induced activity is abolished by amino acid substitution in the GATA2-Zn finger domain or mutation of GATA-responsive element in the TSHβ gene. In CV1 cells transfected with TRH receptor expression plasmid, GATA2-dependent transactivation of αGSU and endothelin-1 promoters was enhanced by TRH. In the gel shift assay, TRH signal potentiated the DNA-binding capacity of GATA2. While inhibition by T3 is dominant over TRH-induced activation, unliganded TR or the putative negative T3-responsive element are not required for TRH-induced stimulation. Studies using GH3 cells showed that TRH-induced activity of the TSHβ promoter depends on protein kinase C but not the mitogen-activated protein kinase, suggesting that the signaling pathway is different from that in the prolactin gene. These results indicate that GATA2 is the principal mediator of the TRH signaling pathway in TSHβ expression