The high-pressure die-casting (HPDC) process involves injecting molten light metal into a steel mold under high pressure, resulting in parts with excellent surface quality and precise dimensions. However, this process subjects the mold to thermal fatigue and mechanical stress, which can lead to damage over time. This study investigated the wear characteristics of two types of inserts made from different steel materials, SKD61 steel and FDAC steel, under HPDC conditions. A thorough approach that combined computer simulations, experiments, and 3D scanning was employed to analyze wear patterns and dimensional changes after up to 300 casting cycles. The results indicate that the SKD61 steel outperformed the FDAC steel in terms of wear resistance and dimensional stability. The maximum deposition values of the SKD61 mold were only 0.009 mm, which was only 25% compared to the FDAC mold, indicating a significantly higher wear resistance. These findings are crucial for selecting and enhancing insert materials in HPDC, ultimately leading to higher-quality and more efficient casting.

This study investigates the torsion characteristics of injection-molded flexural hinges manufactured from common polymers and plastic-based composites. The compliant mechanism provides a nearly constant torque over a specific rotational period. The flexural hinges are created via the injection molding technique, which has the advantage of mass production and low price. The injection plastics are pure polypropylene (PP), acrylonitrile butadiene styrene (ABS), and polyamide 6 (PA6), and the injection composites are PA6 combined with glass fibers. The torsional moment of the ABS flexural hinge ranges from −0.2 to 0.94 N∙m. The torsional moment of the PP polymer typically ranges from −0.6 to 0.8 N∙m. The torsional moment of the PA6 polymer ranges from −0.2 to 1.0 N∙m. Interestingly, the torsional moment diagram for this polymer is comparable to that of ABS, with a stable pattern in both positive and negative ranges. Furthermore, in other words, the PP flexural range is greater than the ABS range. Both ABS and PA6 flexural hinges have a higher level of stability compared to the PP one due to the higher elastic modulus and higher strength of these polymers than the PP polymer. The PP flexural hinge has the lowest negative torsional moment (−0.6 N∙m) compared to ABS and PA hinges. PA6 flexural hinges also have the most stable torsional moment compared to pure polymer varieties. Adding 5% to 10% fiberglass (FG) significantly improves the torsional moment of composite flexural hinges. More flexural hinges from different polymer types should be investigated. Further research should conduct some statistical analysis to clarify the variations between the torques for the various materials. The findings improve our understanding of plastic flexure hinges and expand their applicability.

Beverage bottle caps are usually made from two primary materials: PP and HDPE. In this study, the evaluation criteria were the unnotched impact toughness and the microstructure of PP/HDPE/EVA samples produced by injection molding. The samples were tested according to ASTM D256. PP/HDPE/EVA blends were prepared with various ratios: 47.5/47.5/5, 45/45/10, 42.5/42.5/15, 40/40/20, and 37.5/37.5/25. The results showed that adding EVA to the PP/HDPE blend significantly increased the unnotched impact toughness: from 84.03 kJ/m2 (PP/HDPE/5% EVA) to 85.06 kJ/m2 (PP/HDPE/10% EVA), then decreased to 70.3 kJ/m2 (PP/HDPE/15% EVA), followed by an increase to 83.32 kJ/m2 (PP/HDPE/20% EVA) and 89.42 kJ/m2 (PP/HDPE/25% EVA). The discrepancy in value between the samples with the highest and lowest EVA content was 19.12 kJ/m2. Overall, as the EVA content increased, the unnotched impact toughness also tended to increase. However, the sample with PP/HDPE/15% EVA showed a noticeable decrease.

The authors of the study for this chapter investigated the effects of discharge time on the surface roughness of H13 steel machined by wire electrical discharge. The microstructure displayed dark-colored carbide particles scattering on the martensite matrix. Moreover, sample 2 showed a pulse-on time (T_on) of 6 µs and a pulse-off time (T_off) of 14 µs, which achieved the best surface roughness Ra of 1.91 µm. On the contrary, T_on for sample 8 was 14 µs, and T_off was 14 µs, achieving the highest surface roughness Ra of 3.35 µm. The Taguchi results show that T_on has a stronger effect on the surface roughness than T_off. The outcomes might help to improve the H13 steel wire electrical discharge machining procedure. <!----> <!----> <!----> <!---->