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Higher standards have been set for elbow-type parts’ inner-surface finish in industrial production. The influence mechanism of inlet velocity, bend ratio, and bending angle on the surface quality of the elbow is analyzed to research the surface quality control technology of abrasive flow machining (AFM) elbows, and the surface quality control method of elbows in AFM is established. The machining effect of the abrasive flow is capable of being improved, according to the results of numerical simulation, by raising the inlet velocity; the machining capability of lower curvature radii is greater, whereas the uniformity of the overall machining of higher curvature radii is preferable; the numerical simulation verifies that the analysis of the flow state in the 90° elbow applies to elbows with various bending angles, demonstrating that the numerical simulation analysis represents a significant guide to the experiment results. The numerical simulation results and experimental findings for curvature radius agree, and by raising the inlet velocity or inlet pressure, improved surface quality control is capable of being accomplished for higher curvature radii; the experimental findings demonstrate that increasing the inlet pressure enhances the abrasive flow’s ability to machine, demonstrating that the inlet pressure and inlet velocity are directly proportional to one another. Therefore, the experimental findings confirm the accuracy of the numerical simulations, validate the viability and validity of AFM elbows, and provide technical support for the suggested quality control technology of AFM elbows.

The surface finish (SF) becomes a part of the solder joint during assembly and improves the component’s reliability. Furthermore, the SF influences the solder joint’s reliability by affecting the thickness of the intermetallic compound (IMC) layer at the solder interface and copper pads. In this experiment, five different alloys are used and compared with the SAC305 alloy, two of which, Innolot and SAC-Bi, are bi-based solder alloys. This study includes three common SFs: electroless nickel immersion gold (ENIG), immersion silver (ImAg), and organic solderability preserve (OSP). The performance of three surface finishes is examined in terms of component characteristic life. All of the boards were isothermally aged for twelve months at 125 °C. The boards were then exposed to 5000 cycles of thermal cycling at temperatures ranging from −40–+125 °C. Most of the current research considers only one or two factors affecting the reliability of the electronic package. This study combines the effect of multiple factors, including solder paste content, SF, isothermal aging, and thermal cycling, to ensure that the test conditions represent real-world applications. In addition, the electronics packages are assembled using commercialized alloys. The current study focuses on a high-performance alloy already present in the electronic market. The failure data were analyzed statistically using the Weibull distribution and design of experiments (DOE) analysis of variance (ANOVA) techniques. The findings reveal that the micro and uniformly distributed precipitates in solder microstructures are critical for high-reliability solder joints. Re-crystallization of the thermally cycled solder joints promotes the local formation of numerous new grains in stress-concentrated zones. As the fracture spreads along these grain boundaries and eventually fails, these new grains participate in crack propagation. Aging significantly worsens this situation. Finally, although the ENIG surface finish with its Ni layer outperforms other SFs, this does not imply that ENIG is more reliable in all solder paste/sphere/finish combinations.

Laser polishing is presently regarded as one of the enabling technologies hoped to eventually replace the need for time-consuming and error-prone manual polishing operations which are often required by metallic surfaces. During laser polishing, a thin layer of material is being melted as a result of laser irradiation. Since molten metal is characterized by increased relocation capabilities, laser polishing is generally accompanied by a more or less significant decrease in the surface roughness. The primary objective of this study is to present a comprehensive snapshot of the advancements made over more than one decade with respect to theoretical and experimental investigation of laser polishing technology. However, in addition to the usual review of the state-of-theart in the field, the study places an increased emphasis on the finishing performance of the process, defined through the perspective of pre- and postpolishing surface roughness. The implementation of this metric with strong practical implications has revealed that under appropriate process parameters, certain classes of metallic materials can reduce their average surface roughness by more than 80 %, possibly to Ra=5 nm. Nonetheless, a more rigorous and fundamental understanding of the intrinsic mechanisms underlying laser polishing remains one of the currently unfulfilled premises toward a wider industrial adoption of the process. © Springer-Verlag London 2014.

A multistage inner cone hole (MICH) consists of numerous inner cone holes of varying degrees of conicality and length and is frequently employed in diverse machinery. Due to the use of difficult-to-machine materials and the demand for high machining quality, precision machining has become an urgent challenge. To improve the surface finish quality of MICH, a novel electrochemical machining (ECM) process assisted by a hydraulic self-driven rotating magnetic field is proposed in this paper. A hydraulic self-driven rotating shaft with magnets attached to the cathode is designed, which can be driven by the electrolyte to rotate and generate a rotating magnetic field during the ECM process. The rotating characteristics of the hydraulic self-driven rotating shaft and the rotating magnetic field characteristics are studied via simulations. According to the simulation analysis results, the parameters related to the rotating shaft and the rotating magnetic field are optimized. Finally, the ECM cathode of MICH was machined, and a machining experiment was conducted. The experimental results indicate that the surface finish quality of MICH machined by the proposed ECM is better than that of conventional ECM, the maximum dimensional error is 0.1 mm, and the surface roughness is Ra 0.695 μm.

Free-form surfaces generated by non-uniform rational B-splines (NURBS) are evolving to face turbomachinery component requirements, such as turbine blades to enhanced efficiency. Super abrasive machining (SAM) is presented as a potential process for high-added value components using custom-shaped tools to be adapted to any surface. The adaptability and flexibility of these tool concepts are specifically designed to fit these complex surfaces. This paper presents an innovative manufacturing approach for blade type components using a custom-shaped tool designed through an optimization process that simultaneously optimizes both the shape of the tool and its motion. The proposed method with SAM finishing using a custom-shaped tool is compared against a standard tool and traditional machining process. The result obtained on the blade test case shows that the custom-shaped tools need fewer paths, yet produce more accurate surface finish.

In this study, an interconnection was formed between a Cu/SnAg pillar bump and an Ni-less surface-treated Cu pad through laser-assisted bonding (LAB), and its bonding characteristics were evaluated. The LAB process influences the bond quality and mechanical strength based on the laser irradiation time and laser power density. The growth of the intermetallic compound (IMC) in the joint cross-section was observed via FE-SEM analysis. Under optimized LAB conditions, minimal IMC growth and high bonding strength were achieved compared to conventional thermo-compression bonding (TCB) and mass reflow (MR) processes. As the laser irradiation time and laser power density increased, solder splashing was observed at bump temperatures above 300 °C. This is hypothesized to be due to the rapid temperature rise causing the flux to vaporize explosively, resulting in simultaneous solder splashing. With increasing laser power density, the failure mode transitioned from the solder to the IMC.

In the realm of machining, the surface finish of the final product serves as a pivotal quality indicator, signifying the excellence of the manufactured component. Consequently, a pressing requirement exists for dependable and precise predictive models that can effectively oversee the surface finish of machined parts throughout the in-process stage. This study presents a novel ensemble learning model, specifically the Convolutional Neural Network-Extreme Gradient Boosting (CNN-XG Boost), to classify the ongoing machined surface finish. To this end, a dataset containing images of machined surfaces was harnessed for training various traditional machine learning algorithms, encompassing Decision Tree (DT), Random Forest (RF), XGB, and K-Nearest Neighbors (KNN). Notably, XGB exhibited the highest accuracy at 41.6%. Expanding upon this, a deep learning CNN algorithm was trained, manifesting an elevated accuracy of 62.5% compared to its counterparts. The pinnacle of this endeavor entailed training ensemble algorithms such as CNN + DT, CNN + RF, CNN + XGB, and CNN + KNN. Among these, CNN + XGB stood out by achieving a remarkable prediction accuracy of 98%.

The blade surface roughness of blisk is of significance to performance of aero-engine on the aspects of thrust weight ratio and service life, etc. However, it is difficult to achieve uniform surface finish because of the strong geometry interferences arising from the complex structures, through the processes of manual finishing, belt grinding, and CNC polishing. In this paper, abrasive flow machining (AFM) process is adopted to polish blade surfaces of blisk with the aim to acquire qualified uniform surface finish, by virtue of AFM’s excellent machining flexibility for parts with structures difficult to machine. Researches on surface finishing are taken for the proposed experimental prototype blisk with straight blades, through the approaches of both experiments and numerical simulations, where abrasive media with different mesh sizes and mass fractions are used. Experimental results show that surface roughness values near regions of leading/trailing edges are higher than those in regions of blades’ center, although surface roughness of the whole blades is improved obviously after AFM process. And, results from numerical simulations indicate that there exist irregular flows of abrasive media and high-pressure gradients near the leading/trailing edges, which provides reasonable explanations why uneven surface finish of blades is not achieved. Based on these analyses, a new fixture with guild blocks is proposed and proper fixture parameters are set to efficiently regulate the abrasive media flows near leading/trailing edges, and the validation experiments show that surface finish uniformity of blades is achieved with this apparatus. The conclusion could be drawn from the studies of this paper that uniform surface finish for blisk is achievable through properly designed AFM fixtures.

Sn-10Bi low-bismuth-content solder alloy provides a potential alternative to the currently used Sn-Ag-Cu series due to its lower cost, excellent ductility, and strengthening resulting from the Bi solid solution and precipitation. This study primarily investigates the interfacial evolution and shear strength characteristics of Sn-10Bi joints on a Ni/Au surface finish during the as-soldered and subsequent isothermal aging processes. To improve the joint performance, a 0.2 or 0.5 wt.% dopant of Zn was incorporated into Sn-10Bi solder. The findings demonstrated that a 0.2 or 0.5 wt.% Zn dopant altered the composition of the intermetallic compound (IMC) formed at the interface between the solder and Ni/Au surface finish from Ni3Sn4 to Ni3(Sn, Zn)4. The occurrence of this transformation is attributed to the diffusion of Zn atoms into the Ni3Sn4 lattice, resulting in the substitution of a portion of the Sn atoms by Zn atoms, thereby forming the Ni3(Sn, Zn)4 IMC during the soldering process, which was also verified by calculations based on first principles. Furthermore, a 0.2 or 0.5 wt.% Zn dopant in Sn-10Bi significantly inhibited the Ni3(Sn, Zn)4 growth after both the soldering and thermal aging processes. Zn addition can enhance the shear strength of solder joints irrespective of the as-soldered or aging condition. The fracture mode was determined by the aging durations—with the brittle mode occurring for as-soldered joints, the ductile mode occurring for aged joints after 10 days, and again the brittle mode for joints after 40 days of aging.

EDM is a special type of non-traditional machining technique in which material removal takes place due to repeated electrical discharges at short intervals in the presence of a dielectric medium. It is used in high precision machining of all types of conductive materials such as metals, metallic alloys, graphite and even some ceramic materials. In EDM, the main output parameters are the material removal rate (MRR), electrode wear rate (EWR), and surface roughness ( R a ). It is generally desirable to obtain the maximum MRR with minimum EWR with good surface finish. The dielectrics play a vital role in machining. Even though EDM process has been traditionally used in die sinking industry mostly for machining hard materials, lighter materials like Ti alloy are machined more recently. In some cases, components made out of soft metals like Aluminium alloys are machined in EDM due to the intricacy of profiles, blind prismatic holes and inaccessible areas by other machining methods. This paper aims to investigate the effect of using different dielectrics, viz., biodiesel, transformer oil and kerosene on the material removal rate, electrode wear and surface roughness in EDM. Based on Taguchi’s design of experiments, machining were carried out on Aluminium Alloy 6063 specimens using a die-sinking EDM machine fitted with a copper electrode. The results show that the biodiesel as a dielectric has better performance in MRR, EWR and surface finish in comparison with kerosene and transformer oil. However, performance sustainability and the environmental effect of biodiesel have to be studied.