Hadfield steel demonstrates outstanding mechanical characteristics, merging significant work-hardening ability with substantial ductility. This research intends to examine the impact of plastic deformation on Hadfield steel via the cold rolling (CR) technique. The examined samples included both as-cast specimens and those subjected to cold reduction (CR) of 20%, 30%, and 40%. The Hadfield steel specimens were fabricated through casting and later sectioned with wire cutting. The samples were subsequently affixed with resin and hardener, then ground and polished before characterization. X-ray diffraction (XRD) was utilized for phase identification, and the diffraction data were examined with HighScore software to ascertain the existing phases, full width at half maximum (FWHM), and approximations of crystallite size and microstrain through Williamson–Hall analysis. Moreover, Vickers hardness assessment utilizing a 30 kgf load was conducted to analyze alterations in hardness due to plastic deformation occurring during cold rolling. The findings indicated that augmenting the extent of plastic deformation via cold rolling led to a reduction in crystallite size, decreasing from 33.68 nm in the as-cast state to 32.91 nm (CR 20%), 22.28 nm (CR 30%), and 21.61 nm (CR 40%). Conversely, the microstrain escalated from 0.53% in the as-cast state to 0.68% (CR 20%), 0.72% (CR 30%), and 0.92% (CR 40%). The rise in microstrain signifies an escalation in lattice distortion as assessed via XRD peak broadening analysis with heightened plastic deformation. The Vickers hardness measurements indicated a rise in hardness corresponding to the level of deformation, progressing from 212.1 ± 10.2 HV30/10 in the as-cast state to 401.4 ± 6.6 HV30/10 (CR 20%), 469.7 ± 18.4 HV30/10 (CR 30%), and 525.7 ± 56.0 HV30/10 (CR 40%). The noted enhancement in hardness aligns with strain hardening caused by plastic deformation throughout the cold rolling procedure.
Gas turbines are widely used in modern power generation due to their high efficiency and flexibility. However, using exhaust silencers in exhaust gas systems can increase back pressure, reducing overall turbine performance. The aerodynamic behavior of the splitter inside the exhaust silencer, especially at the trailing edge, significantly affects pressure drop and turbulence intensity. This study aims to optimize the trailing edge geometry of a GE Frame 6FA exhaust silencer splitter using a combination of computational fluid dynamics (CFD) and Bayesian optimization (BO). CFD simulations were conducted in ANSYS Fluent using a poly-hexcore mesh, while the optimization employed a Gaussian process (GP) surrogate model with an expected improvement (EI) acquisition function. Seven trailing edge angles (5°–20°) were evaluated to observe the aerodynamic trade-off between pressure drop and turbulent kinetic energy (TKE). The optimal configuration was found at 13.9°, yielding a TKE of 0.43 J/kg and a pressure drop of 18.38 Pa, well below the industrial allowable pressure drop limit of 34 Pa. The results confirm that the BO-GP framework effectively reduces computational cost while achieving a more aerodynamically balanced silencer design.
The use of asbestos as the main material in brake pad manufacturing has been discontinued due to its toxic nature and serious health risks, including asbestosis, mesothelioma, and lung cancer, thereby encouraging the development of safer and more environmentally friendly alternative materials. This study developed bio-composite brake pads based on mahogany wood powder as a natural fiber combined with brass powder, using polyester resin as the matrix binder and magnesium oxide as a reinforcing agent to enhance mechanical integrity. The fabrication process was carried out using a compaction method followed by sintering to achieve optimal bonding and densification. This research aimed to evaluate the effects of compaction pressure and variations in constituent composition on the wear resistance of the brake pads. Compaction pressures of 3000, 3200, and 3400 psi were applied with mahogany powder to brass powder ratios of 1:4 and 4:4. Wear tests were conducted on all fabricated specimens. The results showed that the highest specific wear value of 9.2 × 10⁻⁴ mm³/kg.m occurred in the 1:4 composition at a compaction pressure of 3000 psi, while the lowest value of 5.5 × 10⁻⁴ mm³/kg.m was obtained in the 4:4 composition at a compaction pressure of 3400 psi. These findings indicate that both compaction pressure and constituent composition significantly affect the wear resistance of brake pads.
Advances in manufacturing technology require accurate, consistent, and efficient drilling processes. Manual drilling of locator holes can cause positional deviations and rely on operator skill. This study aims to design, fabricate, and evaluate a drill jig to produce locator holes with diameters of 6, 8, and 10 mm while accommodating variations in workpiece position and thickness. The research stages included requirement identification, CAD-based design, drilling and clamping force calculations, CAE-based structural analysis, prototype fabrication, and experimental testing. The main structure was made of SS400 steel. Simulation results showed a maximum von Mises stress of 213.32 MPa, maximum displacement of 0.0691 mm, and minimum safety factor of 0.97. Experimental testing was conducted in five trials using a bench drill on an 18-mm-thick SS400 workpiece with a nominal hole diameter of Ø8 mm. Using the drill jig reduced average loading time from 43.20 s to 29.80 s, unloading time from 31.80 s to 22.00 s, and drilling time from 39.40 s to 31.00 s. Average cycle time decreased from 114.40 s to 82.80 s, representing a 27.6% reduction. The average hole diameter with the drill jig was 8.05 mm, closer to the nominal diameter than the 8.20 mm obtained without the jig.
Higher productivity, lower cost, environmental requirement and occupational health have become serious challenges for manufacturing industries nowadays. In this study, a mixture comprising canola oil, emulsifier and ZnO nanoparticles was applied as the cutting oil for face milling of stainless steel SS316L. Previous studies have demonstrated decreasing surface roughness with increasing spindle speed. Numerous previous studies have also revealed decreasing surface roughness with increasing ZnO concentrations. However, a relationship between elevated ZnO concentrations and reduced spindle speeds has barely been addressed. Building on this circumstance, a novel machining strategy was proposed in this study by employing elevated ZnO concentrations as a trade-off strategy to reduce the spindle speeds. The spindle speeds in this study were 1500, 1800 and 2100 rpm. The experiment demonstrated that elevating ZnO concentrations from 1.0 to 4.0 wt% could be used to decrease the spindle speeds from 2100 to 1800 rpm while maintaining acceptable surface roughness. Although future studies are warranted, reducing spindle speed is beneficial for manufacturing industries as it may contribute to lower electrical energy consumption. Furthermore, the proposed trade-off strategy can also be implemented for manufacturing industries located in regions with limited electrical grid capacity, for example, due to restricted capacity of electrical transformers.
