Manufacturing of ultra-fine particle coal fly ash–A380 aluminum matrix composites with improved mechanical properties by improved ring milling and oscillating microgrid mixing

An experimental study is presented of ultra-fine coal fly ash (CFA) aluminum matrix composites produced by successive high-power ring milling of CFA, oscillating microgrid mixing of the CFA–aluminum melt, gravity casting and rapid cooling. Samples corresponding to different CFA concentrations and particle size distributions (1 μm average, or less) are produced and subjected to microstructural and mechanical characterization, including tensile, compressive, impact, hardness and wear testing. While the usual trade-off between increased strength and hardness and reduced ductility and toughness is observed, the obtained ultra-fine particle composites are confirmed to have overall improved mechanical properties compared to composites with larger size particles previously produced by ball milling

Efficient oscillating micro-grid mixing of CFA-aluminium composite melts

Abstract An analytical, numerical and experimental study is presented on the deagglomeration and dispersion of fine coal fly ash (CFA) reinforcing particles in an A380 aluminium matrix using a piston-actuated oscillating micro-grid mixing method with a specially designed grid geometry. Based on real-time measurement of the piston force, the apparent viscosity of the melt and the effectiveness of the deagglomeration are measured indirectly. The oscillating micro-grid mixing process is shown to be considerably more time-efficient that comparative stir-casting processes currently employed, leading to a two-fold or three-fold reduction in processing time for the same or better mixing quality, or alternatively a nearly two-fold reduction in the standard deviation of the micro-hardness throughout the material

Improving the wear resistance of 3D printed spur gears through a free-form tooth flank optimization process

Involute gears have traditionally been the preferred choice for gear transmission systems due to their simplicity and interchangeability. However, there are applications where they do not provide the most durable and efficient solution. While the cost of implementing optimized non-involute gears in most applications often outweighs their comparative advantages, the advent of additive manufacturing has opened up possibilities for designers to explore alternative gear tooth profiles. This is particularly relevant in the realm of plastic gears, where optimized non-involute gears produced through 3D printing can address their primary drawbacks, such as surface durability and wear resistance. In this study, a comprehensive free-form optimization process was conducted to determine the optimal tooth profile that minimizes wear on 3D printed spur gears during operation. The tooth flank geometry was represented using a 4th order B-spline curve, and a genetic algorithm was employed to determine the optimum positions of the control points aiming to minimize wear depth across the tooth flanks. The spur gears were manufactured using Fused Deposition Modeling (FDM) with PLA material. The parameters of the additive manufacturing process were experimentally fine-tuned to achieve the best possible accuracy. To evaluate the performance of the optimized free-form gears, two case studies were implemented, demonstrating that the optimized gears achieved a remarkable reduction of average wear depth by more than 50% and a reduction of maximum wear depth by more than 69% compared to standard involute gears. To further validate the effectiveness of the optimization method, experiments were carried out using an FZG test rig. The profiles of the tooth flanks were measured on a Coordinate Measuring Machine (CMM) before and after the experiments to compare the wear depth against the standard involute gears. The results revealed a significant improvement in the wear resistance of the tooth flanks, with a reduction of wear depth of 44.1%