China Steel (Taiwan)

ABSTRACT Real‐time sensing has become increasingly important in injection molding for understanding melt behavior and improving part quality. Cyclo‐olefin copolymer (COC) is widely used in high‐precision optical components and medical devices due to its excellent optical clarity, low birefringence, and dimensional stability, particularly under cold‐climate and low‐temperature operating conditions, where conventional amorphous polymers may suffer from increased residual stress and optical distortion. Ensuring stable processing and reliable performance of COC components in such environments therefore requires enhanced process monitoring and control strategies. In this study, in‐mold pressure sensing combined with birefringence analysis was employed to investigate the relationship between pressure evolution and residual stress in injection‐molded COC components. Two pressure sensors were embedded at the gate and at the cavity center to characterize pressure drop behavior and a pressure‐derived viscosity index under near‐gate and far‐gate configurations. By integrating real‐time pressure data with optical stress analysis, this work demonstrates how smart sensing strategies can be used to ensure product quality, dimensional precision, and optical performance in injection‐molded COC parts. The results show that the cavity pressure drop was approximately 64% lower than the gate pressure in the near‐gate configuration, with a similar but reduced trend observed in the far‐gate configuration. Consistent variations were also identified in the viscosity index. An increased gate‐to‐cavity pressure drop was found to correlate strongly with improved geometric precision, reflected by reduced out‐of‐roundness, and with lower internal residual stress as revealed by birefringence patterns. Increasing mold and melt temperatures improved flow relaxation but introduced trade‐offs in dimensional stability between regions near and far from the gate. These findings demonstrate the coupled effects of pressure evolution and thermal conditions on part quality and highlight the importance of holistic process optimization in precision injection molding.

The integration of high-quality GaSb layers on GaAs substrates presents a promising route for developing antimonide-based optoelectronic devices on cost-effective platforms. In this work, we investigate the influence of antimony (Sb) flux during the low-temperature antimonidation process, which is proposed to promote Al–Sb reactions and the formation of an AlSb-like interlayer, on the crystallographic orientation as well as the electrical and optical properties of GaSb films subsequently grown on GaAs (001) substrates. Three samples with varying Sb supply conditions were analyzed using high-resolution x-ray diffraction, scanning transmission electron microscopy, and photoluminescence (PL) spectroscopy. Our results suggest that sufficient Sb flux during this initial stage favors the formation of a highly crystalline interlayer with dominant (002) characteristics, which, in turn, enables the subsequent epitaxial growth of GaSb with a (001) orientation. In contrast, reduced or absent Sb flux results in unfavorable (111) or mixed orientations, degraded crystalline quality, and diminished PL intensity. Electrical characterization further confirms that improved crystal orientation correlates with lower sheet resistance and higher carrier mobility. These findings highlight the critical role of Sb availability during antimonidation in determining the performance of GaSb-based heterostructures on GaAs substrates.

The currently available hot briquetted iron (HBI) typically contains approximately 1 wt.% carbon. In the CO-CO2 atmosphere of a blast furnace, carbon loss from iron is significant, accompanied by overoxidation. Based on the high metallicity of HBI, this study designed iron particles with varying carbon contents. These pellets were mixed with three typical blast furnace iron ores-sinter, pellet, and lump- and subjected to thermogravimetric analysis reduction experiments. The investigation explored the effects of substituting 15 wt.% sinter with HBI containing different carbon contents and assessed the resulting impact on the temperature difference between iron and slag melting, ultimately determining the optimal carbon content for blast furnace operations. The findings showed that the addition of iron particles with carbon contents exceeding 1.6 wt.% achieved reduction rates and iron-slag melting characteristics similar to those of typical blast furnace charges. When iron particles containing 3.6 wt.% carbon were added, the iron oxides of various valence states in the charge and pellets exhibited the highest availability of carbon for both direct and indirect reduction. Consequently, the slag melting temperature rose to 1398 °C. Due to the presence of unreacted carbon, the molten iron melted at approximately 1530 °C, while the iron-slag dripping temperature range narrowed to 132 °C, achieving the optimal temperature range for blast furnace application.

Abstract Gas-assisted injection molding (GAIM) introduces high-pressure gas into the mold cavity after molten plastic injection, creating a hollow structure that reduces material usage and improves warpage and cooling deformation, particularly in thick-walled parts. However, conventional GAIM typically employs nitrogen at around 15 °C, which often leads to condensation and pressure drops due to the temperature difference with the molten polymer. These issues result in unstable gas penetration, asymmetric hollow structures, reduced dimensional stability, and surface defects from insufficient gas support. To address these challenges, this study integrates a gas heating module into the GAIM process and systematically evaluates its effects using the short-shot method and spiral-flow specimens. Experimental results show that gas preheating reduces solid material usage by more than 6 % and achieves an average weight reduction above 20 %, attributed to slower cooling and enhanced hollow formation. Heated gas also decreases shrinkage variability by over 20 %, lowers the overall shrinkage rate by ∼5 %, and simultaneously reduces melt pressure by ∼10 % while stabilizing gas output by ∼15 %, thereby improving dimensional stability and process robustness. Furthermore, the hollow ratio is increased by 15–20 % and penetration length is extended by ∼20 %, resulting in more continuous, symmetric, and well-defined hollow structures.

The growing demand for high-quality decorative polymer surfaces has increased interest in Out Mold Decoration (OMD), yet the combined influence of processing conditions and product geometry on film adhesion and deformation remains insufficiently defined. This study establishes an integrated framework that connects OMD process parameters with geometry-dependent deformation behavior using polycarbonate films printed with an ink grid. Adhesion and surface quality were evaluated using 2.5D specimens, while 3D models with varied fillet radii, slopes, and heights enabled quantitative assessment of grid-spacing evolution and thickness distribution. Results show that preheating smooths the film without improving adhesion, whereas increasing the forming environment temperature enhances both bonding and surface quality within the material’s thermal tolerance. Vacuum pressure strengthens film–substrate contact but requires moderation to prevent overstretching. An optimized condition of 100 °C preheating, 90 °C forming temperature, and 2.5 kg vacuum pressure provides a balanced performance. Geometric factors exert strong control over deformation, with small radii, steep slopes, and tall features producing greater strain and nonuniform thinning. These findings establish practical processing windows and geometry guidelines for achieving reliable OMD components that integrate high visual quality with stable adhesion performance.

In injection molding, draft angle design plays a critical role in ensuring smooth de-molding and maintaining surface quality. With the growing emphasis on aesthetics and the increasing demand for the appearance of plastic products, the need for textured plastic components has continuously risen. The coupling between surface texture replication and dimensional accuracy has become an important indicator of product performance. However, systematic studies on the interaction between different polymer materials and draft angle design remain limited. This study aims to investigate the influence of draft angle variation on the surface texture quality and dimensional stability of injection-molded parts by comparing the differences between crystalline and amorphous thermoplastic materials, as well as between commodity and engineering plastics. Four representative polymers, namely polypropylene (PP), polyoxymethylene (POM), acrylonitrile-butadiene-styrene (ABS), and polycarbonate (PC), were selected to examine the impact of material characteristics on surface texture replication after molding. In addition, product geometries incorporating eight draft angles (0° to 3.5°) were designed. Surface texture replication was analyzed using scanning electron microscopy (SEM) and surface profilometry, while dimensional deformation was measured with a high-precision optical measuring instrument. The results show that draft angle variation has a limited influence on the overall trend of dimensional deformation, but it has a significant effect on the clarity of surface replication. Crystalline polymers exhibited generally higher surface roughness than amorphous polymers, and the distinction between commodity and engineering plastics, particularly those requiring higher processing temperatures, also led to higher roughness (PP > POM; ABS > PC). Dimensional deformation was more pronounced in crystalline polymers (POM > PP > ABS > PC). SEM observations further confirmed that higher roughness corresponded to clearer and more distinguishable texture patterns, whereas lower roughness resulted in blurred or indistinct textures.

Gas nitriding was implemented in the current work at a constant nitrogen potential (KN) of 2.0 for 8 h to enhance the fatigue properties of SCM 440 steel, and the results were compared with those of the substrate tempered at the nitriding temperature (475 °C). Fine particle peening (FPP) prior to nitriding imposed a refined structure and induced compressive residual stress (CRS) in the near-surface peened zone. The fine-grained structure provided numerous paths to enhance nitrogen diffusion inwards during nitriding. The compound layer formed on the nitrided SCM 440 steel primarily comprised a mixture of Fe3N and Fe4N; however, the pre-peened and nitrided (SPN) specimens exhibited a higher proportion of Fe3N and a thicker compound layer than the non-peened and nitrided (NPN) counterparts. In addition, FPP prior to nitriding increased both the case depth and the magnitude of the CRS field compared with nitriding alone. The fatigue limits of the substrate (SB), NPN, and SPN samples were approximately 750, 1050, and 1400 MPa, respectively. Gas-nitriding at 475 °C significantly improved the fatigue performance of SCM 440 steel. Moreover, pre-peening prior to nitriding further enhanced fatigue strength and life of the treated SCM 440 steel by introducing a deeper case depth and higher CRS field. Multiple cracks initiation at the outer surface of the SB sample accounted for its lowest fatigue limit among the tested samples. Surface microcracks and pits on the surface of the NPN specimen would be crack initiation sites and harmful to its fatigue resistance. These surface dents were considered to be responsible for fatigue crack initiation in the SPN specimens. Therefore, polishing after nitriding to reduce surface roughness and/or microcracks was expected to further increase the fatigue resistance and the reliability of nitrided SCM 440 steel.