Machining-induced residual stress significantly affects the fatigue life, geometric stability and service performance of machined components. This study presents a fully coupled thermo-mechanical two-dimensional (2D) Finite Element (FE) model to investigate residual stress distributions induced by High-Speed Milling (HSM) of TC4 titanium alloy. The model’s accuracy was validated by comparing the simulated outcomes with experimental data on chip segmentation, cutting forces and temperatures, with relative errors ranging from 6.85% to 12.40%. Beyond model verification, periodic fluctuations of plastic strain and residual stress in the machined surface and subsurface were simulated. Results showed tensile stress dominance at lower cutting speed (150 m/min), while compressive stress prevailed at higher speed (450 m/min), particularly for σ11. Subsurface stress profiles exhibited hook-shaped distributions, with compressive stress peaking at depths of 7–10 μm and diminishing beyond 22 μm. A good correlation was observed between experimental and simulated results, with subsurface stress consistently compressive and increasing with cutting parameters. The effect of thermo-mechanical loads plays a critical role in shaping residual stress distributions; thermal loads primarily influence surface stress, whereas mechanical loads govern subsurface stress. This research provides a comprehensive understanding of residual stress behavior and its impact on fatigue life and service performance.

During the cutting machining of nickel-titanium shape memory alloy (NiTi-SMA), unreasonable machining parameters will lead to severe tool wear and poor surface quality. This article establishes the prediction model relating cutting speed (vc ), feed rate (f) and cutting depth (ap ) to surface roughness (Ra), material removal rate (MRR) and tool wear (VB) based on the Genetic algorithm-optimized BP neural network (GA-BP) by designing full-factor cutting experiments. Experimental findings indicate that the model’s fitting degree is 98.57%, and the maximum relative error is 6.2%. On this basis, the NSGA-II is used for multi-objective optimization and Pareto optimal solution search. The EWM-GRA-TOPSIS method is used to calculate the similarity between the randomly selected 30 sets of Pareto optimal solutions and the ideal solution and sort. The optimal cutting parameters were finally determined to be vc = 79 m/min, f = 0.06 mm/r and ap = 0.12 mm. Using the optimized machining parameters for cutting experiments, the Ra value obtained at a processing length of 40 m is 0.459 μm, the VB is only 0.049 mm and the MRR reaches 9.48 mm³/s. The maximum relative errors between the experimental and predicted Ra, VB and MRR of the optimal parameters are 2.7%, 4.1% and 0.6%, respectively.

Silicon carbide (SiC) is widely used in applications that demand high thermal and mechanical resistance. However, its hardness and brittleness pose significant challenges for machining. To mitigate these challenges, laser treatment can induce controlled cracks in the material, facilitating the machining process by making material removal more efficient. This study aims to analyze the nucleation of cracks in laser-treated SiC using finite element simulations (FEM) and the Mohr-Coulomb failure criterion. The simulations indicated that reducing the laser scan speed increases thermal stresses, generating radial and longitudinal cracks. These cracks nucleate in tensile regions ahead of the laser spot and propagate by shear within the spot. According to the failure criterion, cracks with depths of up to 0.200 mm were predicted. The experimental results corroborated these predictions, showing cracks with depths of up to 0.194 mm, along with increased crack density and width at lower scan speeds. The good agreement between simulated and experimental data validates the theoretical model, demonstrating its ability to accurately predict material behavior under laser processing conditions. This work provides a solid foundation for optimizing laser thermal treatments in hard materials like SiC, improving both crack control and machining efficiency.

Electric discharge machining using a liquid dielectric medium and dry electric discharge machining (dry EDM) are the techniques used for the precision metal working of hard and challenging-to-machine materials. The present work deals with the comparative studies of experiments performed in wet and dry (using compressed air) conditions. An attachment for dry EDM with a rotary electrode was attached to the existing Oscarmax S430 EDM to examine the MRR and SR of Inconel 800, a superalloy. The results show that dry EDM produces a smoother surface finish compared to conventional EDM. In the conventional EDM process, the MRR increased from 0.114 gm/min to 0.318 gm/min as the peak current rose from 8 A to 16 A, whereas in the dry EDM process, it increased from 0.028 gm/min to 0.033 gm/min for the same peak current range. SEM images show that the conventional EDM surface has more irregularity as compared to dry EDM. The study reveals that there is a 23.28% increase in SR within the conventional EDM process under the parametric settings of 3 mm, 16 A, 50 V, 90 µs, 30 µs and 160rev/min. EDS shows that a greater amount of carbon accumulated onto the worked surface in conventional EDM as contrasted with dry EDM. TGRA optimization is also performed to validate the results.

A205 aluminum is a promising new additively manufacturable aluminum alloy. Prior research showed that such A205 aluminum had poor machinability under single-point turning conditions, such as poor surface finish and high-frequency vibrations, as compared to its cast counterpart. This research sought to confirm these results under multi-point milling and determine the effects of two different lubrication methods (flood and MQL) on machining A205 aluminum. In addition to the comparisons in surface finish, force and vibration magnitude, a spectrogram analysis was employed to compare time-series cutting dynamics. The results found that lubrication reduced the average surface roughness up to 80% (average of 3.5 vs. 0.7 µm), cutting forces up to 30% (average of 26 vs. 18 N) and cutting vibrations up to 50% (average of 40.8 vs. 20.3 m/s2) and resulted in more stable, fewer and lower vibrations over time. However, the differences between flood and MQL were not differentiable with any statistical significance for the feeds and speeds chosen. The results suggested the necessity of applying lubrication in A205 machining, but the selection of flood or MQL was not critical.

Deep hole drilling often exhibits poor torque performance, causing reduced surface quality, productivity, efficiency and tool longevity. To address these issues, ultrasonic vibration-assisted drilling (UAD) was deployed. UAD experiments were conducted on the difficult-to-cut AISI-304 stainless steel with deep holes having a significantly large L/D ratio of 40/5. Conventional drilling (CD) experiments were also conducted in the same way to compare with UAD. Torque produced during the experiments was quantitatively and comprehensively evaluated based on three criteria: coefficient of variation (indicating drilling stability and accuracy), maximum torque (relating to tool breakage) and total work done by torque (representing drilling efficiency). The comparison results revealed that UAD reduced average torque by around 63%, maximum torque by about 3.1 times, torque instability by two times and work done by torque by 2.8 times. A multi-objective optimization using Taguchi-based grey relational analysis showed that even in the worst drilling mode, UAD still decreased torque variation, maximum torque and total work done by 24%, 36% and 32%, respectively. The remarkable improvement in torque performance during UAD deep hole drilling is linked to the discontinuous small-sized chips produced in UAD that facilitate chip evacuation, which significantly improves torque performance and the overall drilling process.

In order to improve patient care, it is necessary to increase the lifetime of double modular hip endoprostheses with tapered junctions. One approach to increasing the lifetime of components is to adjust the residual stress state to the load. Therefore, this study investigates the influence of process parameters and the effect of their interaction on the residual stresses of outer tapers manufactured of Ti-6Al-4V. Generally, compressive residual stresses are present after turning. The process parameters cutting speed and feed have an influence on the circumferential and axial residual stresses. The feed significantly influences the residual stresses in the axial direction, while cutting speed affects the residual stresses in the circumferential direction. The depth of cut has no significant effect on the residual stresses in either direction. With increasing cutting speed, the residual stress state in the circumferential direction is shifted toward tensile residual stresses. This can be explained by the decreasing mechanical load on the subsurface and the predominant influence of the thermal effect. In the axial direction, the compressive residual stresses increase with increasing feed. Due to the low thermal conductivity of titanium, the thermal influence presumably predominates in the near-surface area for the analyzed process parameters.

An investigation has been performed to study the compatibility of machining AZ91 magnesium alloy in dry conditions using uncoated and CVD diamond-coated WC-Co inserts. The machining characteristics such as built-up edge (BUE) formation, surface roughness, cutting forces and chip morphology were studied at the cutting speeds, 350, 650 and 950 m/min. The results revealed severe adhesion of the AZ91 Mg alloy on the uncoated WC-Co inserts with increasing cutting speed and contributed to an increase in surface roughness and cutting forces. The CVD diamond-coated inserts have shown negligible built-up edges at various cutting speeds due to their unique properties like low coefficient of friction, low chemical affinity and high thermal conductivity. Snarled types of long continuous chips were observed while machining with CVD diamond-coated WC-Co inserts, whereas short continuous chips were observed with uncoated WC-Co inserts.

Using closed integral components (CICs) not only simplifies the structure and reduces the weight of aeroengine components but also reduces the number of parts and improves overall engine performance. However, there are currently few publicly available reports on the electrochemical machining (ECM) of CIC blades. The key factor influencing the stability of ECM is the flow-field, which is difficult to design for a CIC because its two sides are closed, thereby limiting the direction of electrolyte flow into the processing area. To achieve the ECM of CICs, flow modes involving either lateral or composite liquid supply (LLS or CLS) are proposed, followed by flow-field and cathode-deformation simulation analyses. The simulation results show that the CLS flow-field is more reasonably designed and its electrolyte distribution is more uniform. The maximum cathode deformation under CLS flow-field is only ca. 15 µm. The experiments were conducted to improve the efficiency of CIC ECM and compare the LLS and CLS flow-fields. During processing, the feed rate was increased from 0.2 min/mm to 0.45 min/mm, and the surface roughness (Ra) decreased from ca. 1.29 µm to ca. 0.37 µm. The experiments show that the CLS flow-field offers higher processing efficiency and better surface quality.

The present study investigates the milling of Inconel 718 (IN718) alloy fabricated using laser powder bed fusion (LPBF). Finish milling has been performed using Al-rich ternary-coated end mills under different lubri-coolant environments. An indigenously developed Cryo-MQL technology for greener manufacturing has been employed. Machinability results have been evaluated in terms of milling forces, tool wear progression, wear mechanisms, surface roughness, sub-surface damages and chip characteristics. MQL and Cryo-MQL conditions reduced milling forces by 50.6% and 47.2%, respectively. A 35–67% flank wear reduction has been obtained for the Cryo-MQL, resulting in minimal sub-surface deformation. Cryo-MQL caused the least milling-induced deformation with no transverse microcrack due to an excellent balance of cooling and lubrication actions. Micro-hardness of the machined sub-surface ranged 450–490 HV0.03 (100–400 μm) for Cryo-MQL compared to 435–485 HV0.03 in a deeper sub-surface deformation zone (250–450 μm) for dry milling. The synergy of lubri-coolant actions in Cryo-MQL mitigated frictional tracks, chip-side cracking and chip-edge fracture.