ABSTRACT The aim of this research is to investigate the primecast pattern as a replacement for conventional wax and polymer patterns, which have drawbacks like low stiffness, excessive thermal expansion and high ash content. Material characterization was carried out using Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM) to evaluate thermal properties and particle morphology. The Box-Behnken Design (BBD) statistical method was employed to optimize key L-PBF process parameters, including laser power, scan speed, and skin thickness, to achieve minimal dimensional deviation and maximum density. Results indicated laser power had the most significant impact on density (37.24%) and dimensional deviation (77.80%) in Z-axis, while scan speed and skin thickness influenced the dimensional deviation in X and Y-axis, respectively. Confirmation tests validated the model predictions, highlighting the effectiveness of the L-PBF process in producing high-quality sacrificial Primecast patterns for investment casting.

ABSTRACT Material Extrusion (MEX) is a common additive manufacturing (AM) technique using filament and pellets feedstocks to fabricate polymer, elastomer, and composite parts. However, poor surface finish, mainly due to the staircase effect on curved surfaces, limits its industrial applications. Traditional improvements focus on process optimization or post-processing. This study introduces an advanced 3D printing approach by modifying printer hardware for in-situ filament and pellet co-extrusion. A PLA-TPU composite system leverages their melt flow indices (MFI) to fill staircase gaps, enhancing surface quality. A mathematical model estimates roughness based on build orientation and layer height. Surface quality was analyzed using vision systems and roughness measurement tools, with optimization identifying ideal parameters. This method effectively reduces the staircase effect, improving MEX’s applicability.

ABSTRACT The efficiency of Magnetic Abrasive Finishing (MAF) relies on magnetic fields, abrasive particles, their motion, and the surface being processed. This study integrates ultrasonic vibrations with MAF using nano-sized abrasives (UAMAF) to achieve nanometer-scale surface finishing. A custom setup was developed for finishing tubular components using ultrasonic vibration-assisted MAF. The research investigated the impact of ultrasonic vibrations, finishing duration, and carbon nanotube (CNT) addition on the surface roughness of Al7075-T6 and A356.0-T6 alloy tubes. Results showed that ultrasonic vibrations significantly reduced surface roughness. Adding 0.6 wt% CNTs increased surface roughness variations by 7% and 10% for MAF and UAMAF, respectively. The higher material removal rate (MRR) observed in Al-7075-T6 indicates that UAMAF is more effective on harder materials. Optical microscopy confirmed a three-body abrasion mechanism.

ABSTRACT To help overcome the difficulty associated with the efficient production of large-in-number micro-pit arrays, a voice coil motor driven (VCM-driven) high-frequency micro-impact process is proposed in this study. Recovery, compression and cushioning forces needed for the impact system are provided by in-series dual-compression springs incorporated into the proposed design. Within each impact cycle, the impact shaft returns extremely quickly to its home position allowing for no loss in power transmission. Experiments show that an array of 2,300 compact, regular and highly consistent honeycomb-like micro-pits can be created in just 15.3 s with outstanding efficiency at an impact frequency of 150 Hz, spring stiffness of 1.04 N/mm, and feed-rate of 22.5 mm/s. The surface roughness of the tank-walls created are suitable for possible cell culturing. The success of the proposed process as an alternative to current conventional methods of great-in-number micro-pit array manufacturing has great commercial potential.

ABSTRACT With the increasing demands of the aerospace industry, Pulsed Dynamic Electrochemical Machining (PDECM), combining pulse and vibration electrochemical machining, has emerged as a promising technique for blisk manufacturing. A critical factor in PDECM is the efficient removal of electrolytic products during pulse intervals, which directly impacts machining accuracy and surface quality. This study developed a multi-physics coupling mathematical model for PDECM and proposed a machining parameter optimization framework to ensure effective removal of electrolysis products. Finite element simulations validated the accuracy of the optimization model. Experimental results demonstrated that using optimized parameters with traditionally designed cathode tools achieved a blade deviation of only 0.1 mm, significantly reducing tool correction time and enhancing PDECM efficiency. This work provides a theoretical and practical foundation for improving precision in blisk manufacturing.

ABSTRACT To fill the gap for the impact of electrochemical machining parameters on the electrochemical grinding process, solitary abrasive grinding was introduced to investigate the impact of electrochemical machining parameters on grinding material removal and abrasive wear during grinding. The results indicate that under identical grinding profundity, the grinding material removal volume after high-voltage electrochemical machining in the incipient grinding process was slightly higher than that after low-voltage electrochemical machining. In the subsequent grinding process, the abrasive granule materialize as macro-fractures after low-voltage electrochemical machining, causing the grinding material removal competence to diminish. After high-voltage electrochemical machining, the wear degree of the abrasive granule is alleviated, thereby persisting a higher grinding material removal competence. A grinding model was built to interpret the impact of electrochemical machining parameters on the grinding process. The study provides a theoretical guidance for the selection of electrochemical machining parameters for electrochemical grinding.

ABSTRACT In the present work, electrochemical micromachining (ECMM) was utilized to fabricate uniformly tapered Nitinol needles for endodontic application. A novel dynamic drawing method with stepwise voltage increments was employed to achieve precise uniform tapering during the ECMM process. To better investigate the effect of feed rate, specimen length, duty ratio, and electrolyte concentration on the full taper angle of the tapered needle, an in-house setup of an ECMM was developed. The feed rate had the highest influence (26.35%). Experimental findings verified the designed taper angles for each specimen length to ensure uniform tapering of the fabricated needles. Regression analysis identified optimal parameters: feed rate of 0.32 μm/sec, duty ratio of 21.37%, specimen length of 5.93 mm, and electrolyte concentration of 2.49 M. Validation tests confirmed the reliability of the proposed ECMM process with a novel approach, achieving a minimal error of 1.17%, making it suitable for endodontic applications.

ABSTRACT Fused Deposition Modeling (FDM) is pivotal in creating functional prototypes and end-use parts, with Tough PLA emerging as a favored material due to its durability. However, fine-tuning printing process variables for Tough PLA on the Ultimaker 2 + 3D printer remains challenging. This study employs Taguchi Grey relational analysis to optimize these process variables. L09 Taguchi’s systematic approach and Taguchi Grey Relational Grade Analysis (TGRGA) investigated Layer Thickness (LT), Infill Density (ID), and Nozzle Temperature (NT) at varying levels for which response variables such as Ultimate Tensile Strength (UTS), Average hardness (AH), and Surface Roughness (Ra) are evaluated. Utilizing Taguchi Grey Relational Grade Analysis (TGRGA), enhancements in ultimate tensile strength from 43.182 N/mm2 to 46.56 N/mm2, average hardness from 64 to 67, and Surface roughness from 8.60 µm to 8.35 µm are achieved. This study contributes to advancing additive manufacturing optimization, offering insights into refining Tough PLA part production on the Ultimaker 2 + 3D printer for bio implants like stent application.

ABSTRACT The surface finish required for the application of products to aerospace and defense sectors cannot be produced by additive manufacturing (AM), and hence, a secondary finishing process is required post-additive manufacturing. Consequently, the current study analyses the ability of micromilling to enhance surface integrity for AM Inconel 718. Micromilling has been performed at three different levels of cutting conditions. The force induced during micromilling, surface finish, and top burr width for machined workpieces has been analyzed. A minimum value of 50 nm has been achieved for surface finish post-machining at a feed of 2 µm/flute and a speed of 50,000 rpm. An upmilling strategy has been found to be generating a lower top burr width compared to downmilling with a minimum value of 141 µm. A stability plot has also been constructed for the micromilling of AM Inconel 718 and compared with the stability lobe for wrought Inconel at different cutting speeds.

ABSTRACT Silicon nitride (Si3N4) ceramic is a typically difficult-to-machine material and has been one preferred material for functional microstructures like heat dissipators, reactors, mixers and so on. However, the processing capabilities of conventional manufacturing techniques are inadequate in machined quality and efficient for Si3N4 microstructures with large-aspect ratio (LAR). Waterjet-assisted laser machining (WJALM) is a method that introduces the waterjet assistance into the laser-only machining (LOM) process, thus combining the advantages of LOM with the impact and cooling effects of the waterjet. This makes WJALM become an ideal approach for fabricating LAR microstructures on silicon nitride ceramic. This research concentrates on multi-objective optimization of aspect-ratio (AR) and ablation-area ratio (AAR) of LAR microgrooves by orthogonal experiments and Grey-relational analysis (GRA). Optimal waterjet-laser composite parameters are obtained, and the optimized AR and AAR is 3.324 and 80.1%, respectively.