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Grinding is an effective method for precision machining of difficult-to-machine hard and brittle materials such as carbon/carbon (C/C) composites. Research on grinding force and machined surface quality is crucial for the precision machining process and practical applications of C/C composite components. However, there are currently few studies on ultrasonic-assisted grinding of needle-punched C/C composites, and the material removal mechanism during the grinding process remains unclear. Additionally, a suitable method for evaluating surface quality specifically for needle-punched C/C composites has not yet been established. To address these issues, this paper conducted experiments on both conventional and ultrasonic-assisted grinding for precision machining of needle-punched C/C composites. The influences of ultrasonic assistance and machining parameters on grinding force and machined surface morphology were investigated. The feasibility of using 3D surface roughness parameter Sa to evaluate the surface quality of needle-punched C/C composites was analyzed. The results indicated that the increase spindle speed could effectively reduce grinding force and improve surface quality, while feed rate and grinding depth were inversely proportional to changes in grinding force and surface quality. Compared to conventional grinding, ultrasonic-assisted grinding could significantly reduce grinding force and enhance surface quality. Furthermore, a standardized sampling area of 4 × 4 mm2 for measuring the 3D surface roughness of needle-punched C/C composites was proposed. Additionally, the ratio of the apparent pit area on the surface was introduced as a quantitative measure for analyzing surface damage caused by machining. [ABSTRACT FROM AUTHOR]

Microstructures in glass materials have important applications in fields such as aerospace, MEMS, and medicine. Current non-traditional machining methods used for micro-slit fabrication suffer from poor sustainability, large slit widths, and poor surface quality. To analyze the transformation relationship between the electrical energy and the heat energy from the discharge plasma point of view, a new method of electrochemical-assisted discharge plasma machining of glass microstructures by ultrasonic vibrating wire electrode is proposed. Firstly, the electrothermal energy conversion is studied through simulation and modeling, and the mechanism of improving machining quality by ultrasonic is illustrated. Then, the influence of the key machining parameters on the quality of the slit is studied. The experimental results show that when ultrasonic vibration is applied to the wire electrode, the optimum amplitude is 7.5 μm. The average slit width is reduced by 20.99% and the surface roughness is reduced by 54.23%. Finally, the micro-star structure with a slit width of 64.94 μm and surface roughness of 0.35 μm was successfully machined by selecting the optimum parameters. It is shown that the electrochemical-assisted discharge plasma machining of glass microstructures by ultrasonic vibrating wire electrode can effectively improve the machining quality and stability, providing the feasibility for further machining of more complex microstructures of non-conductive hard brittle materials. [ABSTRACT FROM AUTHOR]

The application of ultrasonic longitudinal-torsional (LT) machining in the field of machining brittle and hard materials such as ceramics and titanium alloys has been increasingly emphasized. Aiming at the existing ultrasonic LT shank, mainly using piezoelectric materials resulting in low power density, overheating failure, and small torsional vibration components, a new ultrasonic LT shank based on giant magnetostrictive materials is designed. The conical transition hollow horn and giant magnetostrictive ultrasonic LT transducer are designed by theoretical analysis method, and the effects of different spiral groove parameters on the resonant frequency and torsion-longitudinal ratio of the horn are analyzed by using finite element software, and the modal analysis is carried out for the shank. Finally, the ultrasonic LT shank is subjected to experimental studies on impedance characteristics, frequency amplitude response, and voltage amplitude response, and the simulation and experimental results show that the designed shank has a resonant frequency of 19.12kHz, a maximum longitudinal amplitude of 14.5μm, a maximum torsional amplitude of 6.1μm, and a maximum torsion-to-longitudinal ratio of 0.46, which is suitable for most of ultrasonic machining, and verifies the correctness of the design methodology. [ABSTRACT FROM AUTHOR]

Post-processing of selective laser melted (SLMed) Ti6Al4V alloy with poor surface quality and low dimensional accuracy is a necessary operation to better achieve its operational performance. Considering the principle and advantages of ultrasonic vibration–assisted machining (UVAM) and textured tools, the synergistic application of UVAM and textured tools is expected to improve the micro-machining performance of SLMed Ti6Al4V alloy. The micro-machinability and machining mechanism of the SLMed Ti6Al4V alloy are investigated by a series of micro-machining with different scanning strategies, different ultrasonic vibration modes, different micro-texture tool types, and different elliptical trajectories. Multifaceted comparisons of machining results are presented in terms of cutting force, cutting temperature, equivalent stress and strain, temperature field, stress field, strain field, and chip formation. The machining results showed that the cutting forces of UVAM are reduced by 56.5 ~ 66.8% compared with conventional machining (CM). The differences in the cutting forces and temperatures of SLMed Ti6Al4V alloys with different scanning strategies are dependent on the microstructures and mechanical properties. The stress and strain fields are significantly affected by the coupled impact effect of cutting motion and ultrasonic vibration, and the UVAM processes improve serrated chip fracture properties. The dual effect of ultrasonic elliptical vibration and textured tools produces better machining performance, especially for the semi-elliptical micro-texture tools. The differences in machining response for different elliptical trajectories are attributed to the effects of tool vibration impact angle and the dynamic cutting thickness, and the machining response with a phase difference of φ = 45° is better. [ABSTRACT FROM AUTHOR]

Aramid fiber–reinforced polymer composite (AFRPC) is popular in aerospace and defense industries owing to its superior thermal and mechanical properties. However, its intricate hexagonal cellular structure and the material's heterogeneous, soft, and brittle characteristics lead to significant surface defects, such as burr formation, wall tearing, roughness, dimensional inaccuracies, and uncut fibers during traditional machining. Such poor machining quality issues notably affect the operational lifespan and functional performance of its sandwich structural components. To address these issues, the rotary ultrasonic assisted machining (RUSAM) process has been introduced. To thoroughly investigate the RUSAM of AFRPC using various cutting tools, a 3D finite element model was developed and validated. This paper mainly investigates the effect of various machining parameters such as vibration amplitude (VA), cutting width (CW), feed rate (FR), and spindle speed (SS) on the cutting force, surface morphology, burr formation, and burr height during RUSAM of AFRPC structure by plane and toothed disc cutters. The burr height was found to decrease with the increase of spindle speed (60.82% and 71.00%) and vibration amplitude (78.15% and 82.32%), whereas increase with cutting width ( 149.81 % and 321.16%) and feed rate (156.53% and 314.83%) during RUSAM by plane and toothed disc cutters, respectively. The pattern of variation of burr height with machining parameters was found similar to that of the cutting force. Significance analysis based on 4 levels, 4 factors orthogonal L 16 ( 4 4 ) experiments revealed the cutting width to be the most influential parameter on the burr height and cutting force followed by the spindle speed, feed rate, and vibration amplitude during RUSAM of the AFRPC core by the disc cutters. Up to 62.54 % reduction in burr height was realized by rotary ultrasonic assisted machining compared to the conventional machining. Under specified operating conditions, the disc cutter generates a higher but less number of burr as compared to the toothed disc cutter without any tearing defects. 3–10% and 5–20% burrs were observed during rotary ultrasonic assisted machining compared to 20–50% and 40–70% burrs during conventional machining of AFRPC structure by plane and toothed disc cutters, respectively. This experimental research will be extremely useful to comprehend the burr formation mechanism and optimize the machining parameters for enhanced surface morphology of AFRPC structures. [ABSTRACT FROM AUTHOR]

Exploring advanced green processing technology is the way to achieve efficient precision manufacturing of difficult-to-machine materials and carbon-neutral development. Thus, the design and manufacture of a large-amplitude longitudinal ultrasonic vibration-assisted milling (LALUVAM) toolholder is conducted in this work. For validation of the developed toolholder a TC4 titanium alloy milling experiment is carried out. Multifaceted analysis are presented in terms of milling force, surface roughness, and residual stress. The results indicate that the LALUVAM toolholder exhibits excellent performance in milling TC4 materials. What's more, the disordered tool feed trajectory is eliminated when using the LALUVAM toolholder in milling TC4. Moreover, resultant forces F is reduced 36.61%. The minimum surface roughness and a smaller range of compressive residual stress can be obtained under LALUVAM condition. Meanwhile, a scaled texture can be generated on the surface of TC4 by using harmonic movement of end mill. In the future, LALUVAM toolholder will be able to meet the 10 μm to 20 μm ultrasonic machining and provide better results in terms of reduced milling forces and surface roughness. [ABSTRACT FROM AUTHOR]

Nomex honeycomb composite core (NHC) is characterized by thin walls and complex hexagonal cells, giving it specific characteristics. However, this particularity generates significant challenges during its shaping, requiring the use of cutting tools of the particular geometry. In this study, experimental tests were conducted on the milling of NHC structure assisted by RUM technology using the UCSB cutting tool which is a toothed milling cutter. However, the experimental procedure fails to follow the cutting process, which complicates the visualization of the chip formation process due to the rapid movement of the cutting tool and the inaccessibility of the surface between the part/tool. Therefore, in order to effectively follow chip formation, a 3D numerical approach to the milling process of the NHC structure, using RUM technology, is developed using Abaqus Explicit software. On the basis of this model, the study focused on the components of the cutting force, the quality of the machined surface, and the accumulation of chips in front of the cutting tool. The numerical simulation results corroborate the experimental test findings, demonstrating the effectiveness of RUM technology in reducing cutting force components by up to 63%. An exhaustive analysis of the impact of the feed component Fy on the quality of the surface obtained was carried out, highlighting that the quality of the generated surface improves when the values of this component are low. In addition, the effectiveness of ultrasonic vibrations in reducing the accumulation of chips in front of the cutting tool is particularly accentuated, especially when large amplitudes are involved. Thus, the simulated results complemented the experimental results by offering coherent theoretical explanations. [ABSTRACT FROM AUTHOR]

Titanium alloy milling is prone to burrs at the edges of the workpiece, which can negatively affect surface integrity and dimensional accuracy, and even lead to part scrap. Ultrasonic vibration–assisted milling technology can effectively inhibit burr generation and improve machining quality. However, the research of ultrasonic vibration–assisted milling on burr inhibition is not clear, so this paper establishes a mathematical model of ultrasonic vibration vertical milling titanium alloy top burr size based on the chip deformation process and specifically analyses the effect of ultrasonic machining parameters on burr through experiments. The experimental results show that the depth of cut has the greatest influence on the burr size, and the ultrasonic vibration has the second greatest influence on the burr. The cutting force and the burr size on both sides of the groove show a trend of "decrease and then increase" with the increase of ultrasonic amplitude. When the ultrasonic amplitude was 3 µm, the cutting forces Fx and Fy were reduced by 34.42% and 31.36%, respectively, and the heights and widths of the burrs on the up milling side and on the down milling side were reduced by 75.49%, 44.33% and 89.16%, 47.82%, respectively, when comparing with no ultrasonic machining. The longitudinal-torsional ultrasonic vibration converted the large piled-up, rolled-up, and serrated burrs into intermittent, small-sized flocculent burrs, which significantly improved the burr morphology and weakened the serrated characteristics of the chips. [ABSTRACT FROM AUTHOR]

This study introduced a new ultrasonic vibration–assisted short electric arc machining method to improve the machining quality of workpieces. This method mitigated abnormal discharge phenomena such as short circuits, partial discharge, and secondary discharge caused by particle bridges formed between electrodes and workpieces owing to ineffective chip removal in conventional short electric arc machining. After both standard short electric arc and composite processing, the macroscopic characteristics and microscopic morphology of the workpiece were compared through experiments. Moreover, the surface morphology, roughness, and elemental energy spectrum of the workpiece were examined and analyzed through ultra-depth-of-field microscopy, electron scanning, and other methods. The results revealed changes in the surface morphology of the workpiece after the integration of a short electric arc machining and ultrasonic vibration. With the introduction of ultrasonic vibration, the workpiece surface exhibited disorder and uniformity, along with a significant reduction in the number of electrical corrosion pits and surface microcracks. Consequently, the thickness of the recast layer decreased by half, and the surface roughness decreased by over 16%, achieving a maximum reduction of more than twice the original state. Additionally, the surface elements of the material were modified. This study introduces a new method for advancing short electric arc technology to improve processing quality, material modification, and technological coupling. [ABSTRACT FROM AUTHOR]

Metallic glass has been widely used in aviation, medical, military, and other fields because of its excellent performance. In view of the poor processability of metallic glass, the introduction of ultrasonic vibration provides a unique idea for it. In order to further explore the influence of ultrasonic vibration on trajectory and machining effect, this paper focuses on the theoretical feasibility of generating a unique type of tool path under different parameter combinations and studies the machining effect of metal glass under this condition. The experimental results show that the frequency coefficient, amplitude, and phase difference are all important parameters that affect the characteristics of tool path and the machining effect of metallic glass. The tool path formed by the appropriate phase difference and frequency coefficient will greatly improve the surface morphology, and the separation characteristics formed under the appropriate parameters can reduce the cutting force by about 50%. In addition, the effect of ultrasonic vibration machining with a frequency coefficient of 2 is the best, the cutting force generated is similar to that of elliptical ultrasonic vibration machining, and the roughness is reduced by nearly 50%. Choosing the appropriate parameters will get the ultrasonic vibration tool path with a positive effect, and will greatly improve the machining quality of metallic glass. [ABSTRACT FROM AUTHOR]

Particle-reinforced titanium matrix composites (PTMCs) are extensively utilized in key aerospace structural components due to their low density, high ductility, oxidation resistance, excellent wear, and high temperature properties. However, the quality of machining is significantly impacted by macro-fracture and pull-out of the reinforcing particles. In order to address the aforementioned issues and elucidate the material removal mechanism of cubic boron nitride (cBN), this study introduces ultrasonic machining technology into conventional single cBN grain grinding and conducts comparative experiments. The impact of machining parameters on material removal ratio, abrasive wear, and surface quality is the primary focus of the investigation. Findings indicate that the implementation of radial ultrasonic vibration-assisted grinding (RUAVG) can effectively reduce the pile-up ratio from 17.3 to 58.3%. Due to the impact of ultrasonic vibration on abrasive grains and their interference with reinforced particles, cBN abrasive grains undergo continuous micro-fracturing, resulting in superior self-sharpening capabilities and sustained sharpness and processing performance of the grinding edge. Compared to conventional grinding, RUVAG achieves material removal via cutting and micro-fracture mechanisms, which effectively prevents reinforcement pull-out and significantly enhances machining quality. [ABSTRACT FROM AUTHOR]

SiCf/SiC ceramic matrix composites are widely used in high-tech fields such as aerospace and usually processed by grinding methods. In the conventional machining (CON-M), the cutting force during machining is increased due to the hard and brittle characteristics of the material, which affects the surface topography after machining. As a new machining method, longitudinal-torsional coupled rotary ultrasonic machining (LTC-RUM) can effectively reduce the cutting force and improve the surface topography after machining. The machining characteristics of SiCf/SiC ceramic matrix composites in LTC-RUM was investigated to improve the service performance of the material, and reduce the energy consumption. However, relatively few studies have been performed on the machinability of SiCf/SiC ceramic matrix composites by LTC-RUM. This paper studies the cutting force and surface topography during machining by experimental methods. Firstly, the motion characteristics of a single abrasive grain during LTC-RUM are analyzed, and the cutting characteristics of the abrasive grain under the both machining conditions are obtained. Secondly, the effects of spindle speed, feed rate, cutting depth, and ultrasonic amplitude on cutting force and surface roughness were obtained by experimental exploration of CON-M and LTC-RUM. Compared with CON-M, the cutting force is reduced by 64.4%, the surface roughness is reduced by 44.5% under LTC-RUM, and the surface topography is significantly improved. The results of this study provide a theoretical and experimental basis for machining SiCf/SiC ceramic matrix composites. [ABSTRACT FROM AUTHOR]

In order to study the influence of machining methods and parameters on the surface quality of carbon fiber reinforced composites (CFRP) in the cutting process, the finite element simulation model of ultrasonic-assisted cutting CFRP was established, the simulation results show that the introduction of ultrasonic reduces the damage degree of CFRP in the cutting process, and the tool attached torsional ultrasonic vibration effect is the most significant. The ultrasonic-assisted torsion and longitudinal cutting tests of CFRP disc were carried out respectively, and compared with the ordinary cutting process, the experimental results show that the introduction of ultrasonic changes the fracture mode of fiber and effectively reduces the surface roughness. The fiber cutting angle (the angle between the cutting speed direction and the fiber direction) is the main factor affecting the surface roughness of CFRP, the effect of ultrasonic is better in the low-speed area, and the direction of fiber can be weakened by high-speed processing. When the amplitude is in the range of 0 ~ 6 μm, with the increase of amplitude, the advantage of ultrasonic is more obvious, and the inhibition of the influence of fiber directivity is more obvious. The results show that large amplitude and small cutting speed can achieve better ultrasonic machining effect; large vibration amplitude and high cutting speed can effectively suppress the influence of fiber directivity. The results are helpful for the high-quality processing of CFRP and other composite materials. [ABSTRACT FROM AUTHOR]

This paper presents an investigation into the machining of CFRP composites using rotary ultrasonic machining. The study aims to analyze how various process parameters influence machining performance and to identify the optimal value of cutting force. The design approach employed isolates the effects of individual characteristics and explores the interactions between them. The results of this study reveal a nuanced interplay between the investigated parameters and the mechanical behavior of carbon fiber-reinforced plastic (CFRP) during rotary ultrasonic machining (RUM). Notably, variations in vibration amplitude (VA), tool rotation speed (TRS), and feed rate (Fr) significantly influenced the cutting force exerted on the CFRP material. Surprisingly, while both VA and TRS exhibited noticeable effects on the machining process, the feed rate emerged as the predominant factor in determining optimal cutting force levels. Specifically, the data illustrate that higher feed rates led to reduced cutting forces, indicating improved machinability. This unexpected inverse relationship prompts a reconsideration of traditional assumptions about the influence of process parameters on CFRP machining. The outcomes suggest that a strategic emphasis on feed rate adjustment can mitigate cutting forces, potentially enhancing the overall efficiency and quality of CFRP machining operations. These findings carry implications for industries reliant on CFRP components, such as aerospace and automotive sectors, offering a practical guide for optimizing machining processes and advancing the broader understanding of CFRP behavior under RUM conditions. The observed trends also open avenues for further research into the intricate dynamics of material removal in composite structures. [ABSTRACT FROM AUTHOR]

The rotary ultrasonic vibration machining (RUM) system composed of ultrasonic transducers, machining tools, and inductive contactless power transmitter (ICPT) plays an important role in precision and efficient ultrasonic machining of difficult-to-machine materials. Due to the influence of leakage inductance, self-inductance of ICPT, the capacitive piezoelectric vibrator, and the machining load, the matching of the RUM system is essential for efficient and reliable power transmission. A new matching topology of dual capacitance series–parallel on the primary side of ICPT is proposed in this paper, with which the RUM system can realize ideal bilateral resonance and simplify the matching structure. The model of the bilateral resonance of the RUM system with a new matching topology is established, and then, the matching capacitance calculation method is proposed. The transmission and load characteristics of the RUM system with the new matching topology are studied. The results indicate that the transmission efficiency and power output vary with the self-inductance and mutual inductance of the ICPT. When the self-inductance of the primary side is equal to that of the secondary side of ICPT, the system exhibits a balanced comprehensive transmission performance. These results are of great significance for the engineering application of the RUM. [ABSTRACT FROM AUTHOR]

Zirconia ceramics are widely used in aerospace, precision machinery, electronics, and biomedical fields because of their high temperature resistance, wear resistance, strong electromagnetic response, and biocompatibility. Nevertheless, high brittleness and low shear strength seriously hinder the large-scale application of zirconia ceramics in industrial production. This paper mainly reviews the research advances on primary machining technologies of zirconia ceramics from two aspects. One aspect is traditional machining of zirconia ceramics, which primarily focuses on the issues such as tool wear, machined surface quality, and cutting force in milling and grinding of zirconia ceramics. And the other aspect is non-traditional machining of zirconia ceramics, which primarily focuses on material removal rate and machined surface quality of zirconia ceramics using the electrical discharge machining (EDM) by assisting electrode method. The machinability and machining quality of zirconia composite ceramics by EDM with the adding conductive phase method have also been analyzed. Furthermore, for the auxiliary machining methods, the effects of ultrasonic vibration-assisted machining (UVAM) and laser-assisted machining (LAM) of zirconia ceramics are comparatively analyzed and elaborated. Subsequently, the research progress of traditional and non-traditional machining of zirconia ceramics is summarized and discussed. Finally, different machining methods of zirconia ceramics were prospected, and their future development trends were discussed, which provides a reference for further improving the machining efficiency and accuracy of zirconia ceramics. [ABSTRACT FROM AUTHOR]

The applications of Nomex honeycomb composite (NHC) structures in aerospace, automotive and defence sectors have been significantly increasing due to their high compressive strength, hexagonal thin-walled structure, ultra-light weight and excellent thermal resistance. Specific applications include composite sandwich structures in helicopter propellers, satellite cabins, aeroplane floors, engine cowls, wings and nacelles. Accuracy of the machined surface of NHC structures is required for adhesive bonding with face-sheets. Conventional machining processes generate machining defects in terms of tearing, damaged cell walls, burr formation, delamination and poor surface quality that result in reduction of strengths of the core structure and its bond with face sheet. Ultrasonic machining is a proven technique to overcome such machining defects and improve the surface quality of NHC structures. Novelty of this research includes the development of a three-dimensional (3D) finite element model to analyse cutting forces, chip formation and machining quality of NHC structures using disc cutter through both ultrasonic and conventional machining processes by providing feed to the workpiece instead of the cutting tool. The significant influence of machining parameters such as depth of cut, feed rate, ultrasonic amplitude and spindle speed on cutting forces was investigated numerically followed by experimental validation. Numerical model in support with experimental results show that cutting forces decrease by increasing ultrasonic amplitude and spindle speed (up to 54.74% and 62.71%, respectively), and increase with the increase of depth of cut and feed rate (up to 60% and 60.48%, respectively). It was also found that the ultrasonic machining reduces the magnitude of cutting forces as compared to conventional machining (up to 42.74%). Surface morphology analysis through scanning electron microscope also indicated improved machining quality achieved by ultrasonic machining at NHC structures' hexagonal cells, triple points and walls. A burr formation of 5% was observed during ultrasonic machining of NHC structures for F y ≤ 3 N , while it was found up to 10% if F y > 3 N , compared to at least 30% burr during conventional machining. To sum up, the employed methodology can be effectively applied for determining the effect of various machining parameters on cutting forces as well as surface quality, chip formation, structural integrity and dimensional accuracy of machined NHC structures during ultrasonic machining process. [ABSTRACT FROM AUTHOR]

Composites with a silicon carbide fiber-reinforced silicon carbide matrix (SiCf/SiC) are difficult to be machined by the conventional processing due to its hardness and brittleness. The longitudinal-torsional coupled rotary ultrasonic machining (LTC-RUM) is regarded as an effective processing for the material; however, the SiCf/SiC composite's material removal mechanism in LTC-RUM has not been reported, as well as the cutting force. In order to better understand the material removal mechanism of SiCf/SiC composites, this study proposed a cutting force model of LTC-RUM end surface grinding of SiCf/SiC composites. Firstly, the motion path of a single abrasive grain was analyzed, and the micromechanical analysis was used to convert a heterogeneous material into an equivalent homogeneous material. Then, a single abrasive grain material removal mechanism was explored by considering the three material removal regions, including ductile region, ductile-to-brittle transition region, and brittle region. The corresponding material removal mechanism of single abrasive grain during each region was analyzed in detail, and the normal and tangential cutting forces were obtained. Finally, a number of designed experiments were carried to verify the developed model and found that the predicted values were in good agreement with the experimental ones, and the maximum relative errors of normal and tangential cutting forces were 8.51 and 10.19%, respectively. Compared with conventional grinding, the cutting force shows a nonlinear decline in LTC-RUM end surface grinding. The results of this study provide a valuable reference for the LTC-RUM SiCf/SiC composites. [ABSTRACT FROM AUTHOR]

Electrochemical discharge machining (ECDM), as a new type of non-traditional machining method, is widely used in the machining of insulating hard and brittle materials such as glass and ceramics. However, there are some problems such as difficulty in circulating electrolyte, resulting in poor quality machining of deep and small holes. In this paper, electrochemical discharge machining with ultrasonic vibration and tube electrode is used to improve the flow field in the machining gap and enhance the machining quality by using the injected electrolyte inside the tube electrode and ultrasonic vibration. First, the temperature distribution state of electrochemical discharge is simulated, and the influence of the coupling effect of the electrolyte injection and ultrasonic vibration on the machining gap is analyzed. And then, the influence weights of each factor were analyzed by orthogonal experiments and further analyzed to obtain the optimized combination of machining parameters, which reduced the entrance size of small holes by 19.3%, increased the machining depth by 18.5% and increased the depth-to-diameter ratio by 46.2% compared with the traditional ECDM. The effect of ultrasonic vibration was studied on the basis of the optimized machining parameters. The results show that the optimized effect of ultrasonic vibration with an amplitude of 7μm is most obvious under the conditions of low pressure and low injection rate. Finally, with the optimized machining parameters, a 5×5 array of small holes and three deep and small holes were machined, demonstrating that electrochemical discharge machining with ultrasonic vibrating tube electrode can be an efficient and high-quality method for machining small holes. [ABSTRACT FROM AUTHOR]

The carbon fiber composites are widely used in many manufacturing fields due to their superior mechanical. Rotary ultrasonic milling (RUM) technology as a promising method is introduced to machining these composites. However, the processing damage is still a common problem for assembly operations. These defects will reduce the surface service performance and the fatigue life of components severely. Fiber cutting angle is a crucial factor that affects the removal mechanism and machining defects of the carbon fiber composites. In this study, an investigation on the fiber cutting angle during RUM of the carbon fiber composites is conducted, and the corresponding theoretical model is proposed. Both RUM with longitudinal vibration (RUM-L) and with longitudinal-torsional vibration (RUM-LT) are studied. In order to compare the improvement of the fiber cutting angle between RUM-L and RUM-LT, a characterization coefficient is developed. The results indicated that the proportional factor between longitudinal and torsional amplitude b = 0.3 is most reasonable for fiber cutting. A new longitudinal-torsional ultrasonic machining system is developed based on this proportional factor. Finally, the pilot experiments are carried out to verify the theoretical model. Experimental results indicate that the fiber cutting angle is in good agreement with the analytical model for calculating. [ABSTRACT FROM AUTHOR]

Longitudinal-torsional coupled vibration rotary ultrasonic machining (LTC-RUM) provides effective surface grinding of difficult-to-machine and brittle materials. The cutting force analysis can assess its machining effect, which is instrumental in further exploring the material removal mechanism. This study proposed a cutting force model of LTC-RUM end surface grinding of zirconia ceramics considering the ductile and brittle stage of the material removal. The corresponding single abrasive particle movement, cutting depth, and material removal rate during each stage was analyzed in detail, and the cutting force evolution was predicted. Several designed experiments were conducted, verifying the developed model's feasibility. The predicted and experimental results agreed well under various input variables. The cutting force was reduced by increasing spindle speed and ultrasonic power while it grew with feed rate and cutting depth. [ABSTRACT FROM AUTHOR]

Longitudinal ultrasonic vibration-assisted machining (LUVAM) is a machining technique that offers several benefits such as low cutting force, good surface quality, and prolonged tool life. A new set of LUVAM spindle with high-frequency vibrations was designed to enhance the efficiency of LUVAM and the critical cutting speed of "tool-workpiece separation." The spindle's stepped axial vibration transducer is designed analytically, and its amplitude is amplified. The spindle's performance was assessed by measuring resonant frequencies and amplitudes of tungsten carbide and high speed steel tool at varying lengths. Experimental results showed that the transducer's maximum resonance frequency was around 33.52 kHz, and its maximum amplitude was approximately 24.03 μm. The maximum spindle speed exceeded 20,000 rpm, and the runout error was low during high-speed operations. Additionally, Inconel 718 was machined with the new spindle, and the experimental cutting force, machining temperature, surface morphology, chip, and surface integrity were analyzed under different machining parameters. The test results showed that LUVAM could successfully reduce cutting force and temperature while improving surface integrity when separation conditions are met. Compared to conventional machining, LUVAM reduced cutting force and average cutting temperature by up to 23.3% and 19.8%, respectively. The new spindle design provides a new approach for high-quality, efficient, and eco-friendly machining of difficult-to-cut materials. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration–assisted machining (VAM) is a process in which a tool or workpiece is vibrated using ultrasonic frequency small-amplitude vibrations to improve cutting performance, and an ultrasonic transducer usually generates these vibrations. This study investigates how two-dimensional vibrations are generated using axially polled piezoceramics. Modifying the wave propagation in geometric ways by creating a notch at the front mass, the longitudinal response excited by the axially polled piezoceramic discs can be converted into combined longitudinal and bending vibrations at the transducer front mass. Finite element analysis (FEA) software COMSOL is used to study wave propagation, and ANSYS is used to optimize the transducer's mechanical structure, while an equivalent circuit approach is used to analyze the electrical impedance spectra and confirm its resonance frequency. An experimental analysis of impedance response and amplitude of generated vibrations using the novel 2D ultrasonic transducer is conducted to validate the numerical and analytical results, which shows that resonance frequency results are in very good agreement with the theoretical model. Finally, the proposed design is validated by preliminary test results that demonstrate its performance and principles. [ABSTRACT FROM AUTHOR]

As the core component of the rotary ultrasonic machining (RUM) system, the working frequency of the ultrasonic vibration unit and the actual tool vibration amplitude in RUM are important for the machining quality. The electrical characteristics of the ultrasonic vibration unit have a close correlation with both factors. Due to the difficulty in measuring the electrical characteristics of the ultrasonic vibration unit in the RUM system directly, the research on the effect of force load during machining on the variations of its electrical characteristics is relatively little. In this paper, the electrical characteristics of the ultrasonic vibration unit in a typical RUM system are investigated. Firstly, the relationship between electrical parameters and the resonant frequency of the ultrasonic vibration unit is investigated when different tools are clamped by the ultrasonic transducer. The ultrasonic vibration is designed to work in the local resonant state to adapt to various cutting tools. Then, rotary ultrasonic drilling experiments are conducted to study the effect of processing parameters on the electrical characteristics of the ultrasonic vibration unit. An experimental platform is designed where we can directly monitor the voltage signals and current signals of the ultrasonic vibration unit during the machining, and the variations of electrical parameters under different machining conditions are investigated. It is found that the variations of electrical parameters are significant under different ultrasonic voltages but not under different feed rates. [ABSTRACT FROM AUTHOR]

Surface texturing is a potential approach to achieving excellent surface performance. To realize high precision and efficiency in micro-texturing fabrication, a surface texturing method utilizing an ultrasonic surface rolling process is proposed. Firstly, the feasibility and geometric controllability of micro-texture preparation using ultrasonic surface rolling process are analyzed. Then, a contact theory model of ultrasonic rolling texturing process is established, which can describe the geometric relationship of the micro-texturing generation region. Based on the elastic–plastic theory, simulations of single-pass and multi-pass ultrasonic rolling texturing processes are developed to elucidate the formation and strengthening mechanism of micro-textures, and further characterize the effects of ultrasonic rolling machining parameters on micro-textures. A series of validation tests of ultrasonic rolling texturing are implemented on AISI 5140 steel. Simulation and experimental results show that the ultrasonic surface rolling process can fabricate micro-groove arrays with the periodic distribution. The validity of the theoretical and finite element models is confirmed by the comparison results. It is demonstrated that the ultrasonic rolling texturing process is a feasible and efficient way to fabricate controllable micro-textures. [ABSTRACT FROM AUTHOR]

To solve the problems of high cutting forces, severe tool wear, and poor surface integrity faced by advanced materials in aerospace manufacturing, multi-dimensional vibration machining (MDVM) is receiving unprecedented attention. MDVM utilizes workpiece and/or tool vibration excited in different directions to achieve high quality and efficient machining of aeronautical hard-to-cut materials. This paper covered typical MDVM hardware systems based on different vibration mechanisms, vibration application methods, and control methods, discussed the machining mechanisms such as friction reversal and contact-separation, and displayed the application effects in extending tool life, improving surface integrity, and manufacturing functional surfaces. The diversity of vibration mechanisms and the complexity of vibration modes of the MDVM system made it difficult to develop a unified design method for vibration systems and to demonstrate the machining mechanism under the coupling of different ultrasonic-induced effects. Therefore, it is an important development direction for future research to investigate the vibration and machining characteristics of MDVM systems and reveal the unified law. [ABSTRACT FROM AUTHOR]

Ceramic rock slab is a kind of new material with the advantages of high hardness, wear resistance, and high-temperature resistance, and it is widely used in industry and households. However, problems such as easy chipping and serious tool wearing occurred in conventional grinding (CG). To overcome these challenges, this work introduces rotary ultrasonic grinding (RUG) in processing ceramic rock slabs. Study the theoretical motion trajectory of single abrasive grain and the removal mechanism of hard and brittle materials in RUG, and analyzed the influence of amplitude on cutting force in finite element simulation of single abrasive grain. A comparative process experiment of RUG and CG was performed on the hole processing of ceramic rock slabs. The experimental results showed that compared with CG, the cutting force and chipping area of RUG were reduced by 40.4 and 14.3%, respectively. The cutting force and chipping area decreased with the increase of the spindle speed and increased with the increase of the feed speed. With the increase of ultrasonic amplitude, the cutting force and chipping area decreased gradually, and the tool wear rate decreased from 0.54 to 0.10%, which effectively suppresses the spalling of abrasive grains on the surface of the tool and extends the life of the tool. [ABSTRACT FROM AUTHOR]

A study on ultrasonic vibration-assisted electrical discharge machining (UVEDM) micro-hole, which mainly includes three key designs, was conducted to improve the machining performance of the electric discharge machining (EDM) micro-holes on TC4 titanium alloy. First, a mathematical model for the velocity of the flow field in the interelectrode gap was established. Consequently, the effect of the presence or absence of ultrasonic vibration on the flow velocity was analyzed. Furthermore, based on COMSOL Multiphysics, the two distributions of the flow field and the debris in the interelectrode gap were simulated, and the influence of ultrasonic amplitude on them was analyzed. Finally, the study of UVEDM micro-hole machining with different ultrasonic amplitudes was conducted. The machining performance of the UVEDM micro-hole was found to increase with the increment of the ultrasonic amplitude and the optimal value of 5.22 μm, while the performance decreases when the ultrasonic amplitude goes beyond the optimal value. Compared with EDM micro-hole, the MMR is increased by 2.4 times, and the electrode loss and hole taper are reduced by 56% and 24%, respectively. [ABSTRACT FROM AUTHOR]

As a new method developed for machining difficult-to-cut materials, ultrasonic vibration–assisted machining technology not only could be effective in reducing cutting force and temperature but also could be significant in obtaining residual compressive stress. Especially, residual compressive stress is essential to realize anti-fatigue manufacturing for components. However, in recent years, research on residual stresses of ultrasonic vibration–assisted machining mainly focuses on experimental and finite element analysis methods. In this paper, an analytical model was established by considering the effect of ultrasonic vibration to predict residual stresses and reveal the mechanism for UVM of in situ TiB2/Al-MMCs. And a series of experiments were conducted to verify the residual stress model proposed and analyze the effect of ultrasonic vibration and cutting parameters on the surface residual stress. The results show that the predicted residual stresses are in good agreement with measured residual stress. Cutting parameters have a significant effect on the surface residual stress by influencing cutting force and cutting temperature. Residual compressive stresses could be achieved in both UVM and conventional milling, and residual compressive stresses in the former are larger than that in the latter. With cutting speed and cutting depth increasing, the relative increase ratio between UVM, and CM decreased gradually, while with feed rate increasing, it increased first and then decreased slightly. [ABSTRACT FROM AUTHOR]

Rotary ultrasonic machining is a cost-effective and precise machining method for hard and brittle materials. Aiming at processing SiCp/Al composites, a rotary ultrasonic grinding spindle is proposed in the present study. Expressions were established to calculate the displacement, rotation angle, bending moment, and shear force of the vibrating elements based on the Mindlin moderately thick plate theory. Combining continuous and boundary conditions of vibrating elements with the proposed expressions, the vibration model and frequency equation of a longitudinal-flexural resonating transformer with a large load were established. Then two transformers were designed according to the frequency equation. The resonant characteristics of the transformers were studied using finite element analysis, impedance analysis, and ultrasonic resonance experiments. The obtained results show that the maximum deviation between the resonant frequency and the design frequency of the transformers was 4.95%. Moreover, the maximum deviation of the positions of the pitch circles was 6.51%. It is concluded that the proposed designs have high accuracy. Finally, the orthogonal single-factor experiments of SiCp/Al composites were performed with and without ultrasound. The obtained results show that introducing ultrasonic vibrations significantly reduces the grinding force and the surface roughness while improving the surface quality of the SiCp/Al workpiece. The present study is expected to provide experimental fundamentals to further improve the structure of the grinding spindle, optimize process variables of ultrasound-assisted grinding, and improve the processing efficiency. [ABSTRACT FROM AUTHOR]

Ceramics and other hard-and-brittle materials are very effectively processed by longitudinal-torsional coupled rotary ultrasonic machining (LTC-RUM), which cutting force evolution and the effects of processing parameters on the material removal mechanism need to be optimized. This study introduced the LTC-RUM cutting force model of zirconia ceramics based on the brittle material removal mechanism. Firstly, the kinematic analysis of a single abrasive grain was performed, with further consideration of the material removal volume, the effective contact time, and the impact force per one ultrasonic vibration cycle. Then, the longitudinal-torsional coupled vibration of the core tool was analyzed from the wave energy conversion standpoint. The analytical model was finalized and experimentally verified by LTC-RUM tests, which results closely correlated with the ones predicted via the proposed model. With the spindle speed, feed rate, and ultrasonic power variation, the maximum discrepancies between the predicted and experimental cutting forces are 15.51, 13.24, and 8.3%, respectively. The results obtained are considered instrumental in predicting the effects of processing parameters on the cutting force during LTC-RUM of ceramics and their further optimization. [ABSTRACT FROM AUTHOR]

Metallic glass is an excellent material for optical, electromagnetic, and structural parts due to its high strength, high hardness, wear resistance, and corrosion resistance. But due to its high strength and high hardness, it is difficult to be machined, which hinders the further wide application of metallic glass in industry. Some research on traditional and non-traditional machining of metallic glass has been done in recent years. In traditional machining, the related research is mainly focused on machined surface quality, tool wear, and cutting force in turning, milling, and grinding of metallic glass. In non-traditional machining, related research is mainly conducted on machined surface quality and material removal rate by sinker electrical discharge machining (Sinker EDM) metallic glass. The relevant machinability of wire electrical discharge machining (WEDM) and wire electrochemical micro-machining (WECMM) metallic glass is also analyzed and elaborated. Meanwhile, some scholars have carried out study on the laser and ultrasonic welding machining. Based on the above statement, this paper mainly summarizes and analyzes the research progress and some results of traditional and non-traditional machining of metallic glass. Then the machining development trend of metallic glass and further application is discussed, which provides certain reference for furtherly improving machining precise and efficient of metallic glass. [ABSTRACT FROM AUTHOR]

There is a tremendous increase in the demand for converting biomaterials into high-quality industrially manufactured human body parts, also known as medical implants. Drug delivery systems, bone plates, screws, cranial, and dental devices are the popular examples of these implants - the potential alternatives for human life survival. However, the processing techniques of an engineered implant largely determine its preciseness, surface characteristics, and interactive ability with the adjacent tissue(s) in a particular biological environment. Moreover, the high cost-effective manufacturing of an implant under tight tolerances remains a challenge. In this regard, several subtractive or additive manufacturing techniques are employed to manufacture patient-specific implants, depending primarily on the required biocompatibility, bioactivity, surface integrity, and fatigue strength. The present paper reviews numerous non-degradable and degradable metallic implant biomaterials such as stainless steel (SS), titanium (Ti)-based, cobalt (Co)-based, nickel-titanium (NiTi), and magnesium (Mg)-based alloys, followed by their processing via traditional turning, drilling, and milling including the high-speed multi-axis CNC machining, and non-traditional abrasive water jet machining (AWJM), laser beam machining (LBM), ultrasonic machining (USM), and electric discharge machining (EDM) types of subtractive manufacturing techniques. However, the review further funnels down its primary focus on Mg, NiTi, and Ti-based alloys on the basis of the increasing trend of their implant applications in the last decade due to some of their outstanding properties. In the recent years, the incorporation of cryogenic coolant-assisted traditional subtraction of biomaterials has gained researchers' attention due to its sustainability, environment-friendly nature, performance, and superior biocompatible and functional outcomes fitting for medical applications. However, some of the latest studies reported that the medical implant manufacturing requirements could be more remarkably met using the non-traditional subtractive manufacturing approaches. Altogether, cryogenic machining among the traditional routes and EDM among the non-traditional means along with their variants, were identified as some of the most effective subtractive manufacturing techniques for achieving the dimensionally accurate and biocompatible metallic medical implants with significantly modified surfaces. [ABSTRACT FROM AUTHOR]

To address the problem of the poor stability of ultrasonic machining of wave-absorbing honeycomb material, this study takes ultrasonic cutting of wave-absorbing honeycomb material with a disc cutter as the research object and establishes a multi-degree-of-freedom mathematical model of the cutting system based on the relative positions of the tool, the wave-absorbing honeycomb material, and the motion characteristics of the tool. On this basis, modal analysis of the disc cutter and the honeycomb cell wall plate is carried out to draw the Lobe diagram of ultrasonic cutting stability, the process experimental parameters are determined to accord to the solved stability Lobe diagram, and machining stability verification experiments are carried out. The experimental results show that the machining parameters in the stable zone of the Lobe diagram result in a neat and clean surface, less fibre pullout, a complete outer substrate, and less tool wear than those in the critical and unstable zones, thus verifying the correctness of the theoretical model and the stability Lobe diagram. [ABSTRACT FROM AUTHOR]

In order to study the influence of spindle speed and amplitude on the surface integrity, TC18 titanium alloy samples were milled by the process of conventional milling and longitudinal ultrasonic vibration assisted milling. The experimental data were obtained by dynamometer, thermometer, scanning electron microscope, X-ray diffractometer, and three-dimensional surface topography instrument for observation and analysis. The results show that the spindle speed has a significant effect on the cutting force, cutting temperature, surface morphology, and surface residual stress. Compared with conventional milling, the surface micro-texture produced by longitudinal ultrasonic vibration assisted milling is more regular, and the cutting force and cutting temperature can be reduced by 34.1% and 19.5%, respectively. Then, the surface residual compressive stress and surface roughness can be increased by 50.9% and 163.88%, respectively. In addition, a certain depth of plastic deformation layer can be formed under the surface of ultrasonic vibration machining, and the depth of deformation layer increases with the increase of amplitude, and when the amplitude is 4 μm, the depth of plastic deformation can reach about 5.2 μm. This study lays a theoretical foundation for further research and optimization of ultrasonic milling technology for difficult machining materials. [ABSTRACT FROM AUTHOR]

Micro-structure on metal surface can be created with high precision and good surface quality by ultrasonic-assisted electrochemical micromachining (USEMM). One of the prevalent material removal mechanisms in ultrasonic machining (UM) is cavitation erosion. However, the mechanism of material erosion is not clear and worth investigating. This study of the mechanical and chemical effects of the ultrasonic vibration on the 6061 aluminum alloy is targeted to reveal the material processing mechanism in USEMM. Based on the built model, the velocity of micro-jet produced near the workpiece surface by ultrasonic cavitation reaches up to 350 m/s when bubble collapses computed by software MATLAB. The impact of micro-jet produces plastic micro-pits on the metal surface and the convex peak around the edge of the pits, which is verified in ABAQUS software. The metallographic microscope and curves of the electrochemical polarization behavior results indicate a significant grain refinement and a marked increase of anodic dissolution current, as well as a weaker resistance than the original workpiece in NaNO3 electrolyte during UM. The current-time curve during machining demonstrates the passive layer forms on the metal surface and then breaks down at the time of less than 0.0066s in USEMM. Micrographs of scanning electron microscope (SEM) of the machined surface in different stages show that many uniform and flat pits are formed in USEMM, compared with the local uneven pits in EMM. [ABSTRACT FROM AUTHOR]

The ultrasonic transducer employing helical slots to generate longitudinal-torsional (L&T) ultrasonic vibration is popular in the field of hard and brittle material machining. However, the design approach for this type of L&T ultrasonic transducer is not well established. An improved design model combining equivalent circuit theory and material parameter equivalent method based on stiffness variation was proposed in this study. The structure parameters of the transducer can be obtained according to given resonance frequency and nodal position. The model can further predict electrical characteristics and mechanical responses under specific excitation. For the preliminary verification of this theoretical model and the optimization of the transducer, finite element analyses were carried out to investigate the influences of slot structure parameters on dynamic performances in terms of resonance frequency, frequency separation, and amplitude of L&T vibration. After that, a prototype was manufactured according to the design results, and the measurements of impedance curve and vibration amplitude were conducted. The experimental results indicate that this prototype resonates at 24,920 Hz with an effective electromechanical coupling coefficient of 0.19. Meanwhile, the vibration amplitude in longitudinal direction is 8.1 μm and that in tangential direction is 5.6 μm under 70-V sinusoidal voltage excitation, which are consistent with the theoretical design and simulation results. Furthermore, machining tests demonstrate that surface roughness reduction and surface quality improvement can be gained by adopting this L&T ultrasonic transducer, compared to using the longitudinal vibration transducer. The proposed design approach was validated and this study can provide guidelines for the design of L&T ultrasonic transducer for rotary ultrasonic machining (RUM). [ABSTRACT FROM AUTHOR]

Carbon fiber–reinforced plastic (CFRP) composites are extensively being applied in manufacturing sectors because of their extraordinary characteristics. However, CFRP composites often require some extra machining processes to improve the dimensional accuracy and component integrity of CFRP composites in manufacturing industries. The ultrasonic machining (USM) process progressively has been examined due to its greater ability in machining difficult to cut, brittle, and hard materials such as CFRP composites and due to its relatively low machining cost. Furthermore, USM shows to be a promising process with better surface quality, lower cutting force, less or no fiber fracture, laminate delamination, and lower tool wear rate. Recently, USM has been extensively investigated by many researchers for the machining of CFRP composites. This paper explores the literature and presents a comprehensive review of the advances in USM of CFRP composites by classifying the studies reported in two perspectives. First, the review summarizes most of the reported studies starting from 2011 to 2020 based on the applied USM process, equipment/system/platform used to carry out experiments, considered process parameters and output variables, and challenges investigated or gap filled. Then, the reported studies are summarized considering the type of USM process variant, CFRP composite, adopted process parameters on machining characteristics, and their respective results and conclusions. The aim is to present the current research status in USM of CFRP composites and thus provide guidance and foundation for future research. [ABSTRACT FROM AUTHOR]

Due to the notable advantages of ultrasonic-assisted machining, this technology is being more and more adopted in different manufacturing processes. Aramid honeycomb structures are among materials for which ultrasonic-assisted machining has become an interesting alternative thanks to its effect in reduction of machining forces and less micro imperfections. A considerable number of research works have addressed micro machining defeats in ultrasonic application such as dust generation and fiber delamination in Aramid honeycomb workpieces. However, in this study, a great attention is dedicated to the geometrical errors observed in the workpieces in cutting process of Aramid honeycomb structures using ultrasonic technology. The effect of different elements involved in robotic-based ultrasonic-assisted cutting process of Aramid honeycomb structures on these error types has been studied. To proceed this goal, a machining force estimation model is experimentally developed using the machining forces captured during the execution of several cutting tests. An on-site measurement process for measuring the geometrical errors in resulted workpieces is presented. The compliance behavior of robot-tool system is simulated using an extended virtual joint method (VJM) approach. In this approach, the machining tool is considered an additional joint-link system attached to the 6-revolute joint industrial system. Simulation results based on this method applied on the case study showed that the portion of contribution of industrial robotic arm to the compliant errors of process is negligible compared with the one of ultrasonic cutting knife. An offline compensation algorithm is proposed based on the developed machining force and tool compliance behavior models. Experimental results supported the efficiency of the proposed compensation method in reducing the geometrical error by up to 95% based on the machining features. [ABSTRACT FROM AUTHOR]

Cutting force is the predominant output variable in rotary ultrasonic machining (RUM). It dictates other output variables, such as tool wear, cutting temperature, edge chipping, etc. It is desirable to develop a mechanistic model to predict cutting force and reveal the underlying cutting tool-workpiece interaction in RUM. Numerous researchers have developed theoretical approaches to predict cutting force in RUM; nevertheless, the combined effects of material removal on cutting force model have not been investigated. RUM has been used for machining rocks in several recent experimental investigations. However, there are no reports on cutting force model for RUM of rocks. This work bridges the gap and reports an improved mechanistic cutting force model. The model is derived based on the ductile mode removal and brittle fracture mode removal of rock under the indentation of a single abrasive particle. The cutting force model for RUM of rocks is then developed by aggregating the effects of all active abrasive particles bonded to the tool end face. Based on this model, the relationships between input variables (tool rotation speed, feedrate, ultrasonic vibration amplitude, abrasive size, abrasive concentration, and tool size) and cutting force are predicted. Experiments have been conducted and the experimental results agree well with the model predicted trends. [ABSTRACT FROM AUTHOR]

Aluminium 8112 alloy has become a leading material in the aluminium family and currently used in the aerospace and automobile industries due to its excellent chemical and mechanical properties. However, during machining of aluminium alloy, one of the challenges faced by the manufacturing industry is the material adhesion, which increases the rate of chips discontinuity at the machining region and leads to a high surface roughness of the workpiece. The focus of this research is to proffer solutions to this material adhesion by implementing vegetable oil that is copra oil-lubricant, titanium dioxide (TiO2) and multi-walled carbon nanotube (MWCNTs) nano-lubricants during end-milling of AA8112 alloy. Also, using quadratic rotatable central composite design (QRCCD) to study the effects of the machining parameters under minimum quantity lubrication condition, this research used the two-step method to synthesise the nano-lubricants and carried out the homogenisation using the magnetic stirrer and ultrasonic cleaner machine. The study considered five machining factors, including spindle speed, feed rate, length of cut, depth of cut and helix angle. The result from the surface roughness shows that the TiO2 nano-lubricant reduces the surface roughness with 10% and 17% when compared with the MWCNTs nano-lubricant and copra oil. The minimum surface roughness of 1.15 μm, 1.16 μm and 1.35 μm, for the three machining environments, was achieved, respectively. Spindle speed is the most influential machining parameter, followed by the feed rate. The result of this study will aid the manufacturing industry to produce an excellent quality product for a cleaner manufacturing system. [ABSTRACT FROM AUTHOR]

Delamination, an inter-ply debonding failure phenomenon, is considered as the most undesirable and challenging failure mode in hole making of carbon fiber-reinforced plastic (CFRP) composite laminates. The existence of delamination, even small ones, noticeably damages the strength and stability of the assembled products. It is reported that delamination is responsible for up to 60% of composite components' rejection during assembling. In order to reduce delamination, rotary ultrasonic machining (RUM) has been studied and utilized in hole making of CFRP composites. Existing investigations on delamination of CFRP composites in RUM hole making are experimental studies, in which several methods (such as adjusting input variables and the use of supportive plate) to reduce delamination are reported. To understand delamination generation mechanisms and predict delamination initiation, theoretical investigations are needed. Cutting force models in RUM of CFRP composites have been developed, and it is well accepted that delamination is correlated to thrust force. However, there are no reported investigations to predict delamination initiation and study the impact of thrust force on the delamination of CFRP composites in the RUM hole-making process. Finite element analysis (FEA) could be an effective way to study the delamination in the RUM process. In this paper, FEA was conducted to predict delamination initiation and establish the relationship between the thrust force and delamination thickness in RUM, for the first time. In addition, experiments were conducted to validate the FEA model. The proposed model was proved to be effective in predicting delamination initiation, and the trends of the FEA results agreed well with those of the experimental results. [ABSTRACT FROM AUTHOR]

Ceramic matrix composites of type C/SiC have great potential in space applications because of their superior properties such as low density, high wear resistance, and high-temperature resistance. However, due to their heterogeneous, anisotropic, and unstable thermal properties, the machining is still challenging to achieve desired efficiency and quality. For advanced materials, rotary ultrasonic machining (RUM) is considered as a highly efficient technology. Predicting mechanical load in RUM can help to optimize input variables and reduce processing defects in composites. In this research, a mathematical axial drilling load (force and torque) model has been developed based on the indentation fracture theory of material removal mechanism considering penetration trajectory and energy conservation theorem for rotary ultrasonic drilling (RUD) of C/SiC. Experiments were conducted on C/SiC composites to validate the model, and experimental results agreed well with model predictions with less than 14% (force) and 10% (torque) error. Therefore, this theoretical model can be effectively applied to predict axial drilling load during RUD of C/SiC. The relationships of axial drilling force and torque with machining process parameters, including spindle speed, feed rate, and ultrasonic power, were investigated. A specific range of experiments was carried out to demonstrate the benefit of ultrasonic vibration in RUD over conventional drilling (CD) on mechanical load for a designed drilling tool. It was noticed that RUD outperformed CD with a maximum of 38.11% and 34.30% in axial drilling force and torque reduction, respectively. The influence of drilling tool flute length on drilling performance was also elucidated based on a set of experiments using several designed drilling tools. [ABSTRACT FROM AUTHOR]

Subsurface damage (SSD) generated in rotary ultrasonic machining (RUM) process significantly deteriorates the technological and structural performance of the optical components. However, the invisibility of subsurface cracks underneath the machined surface makes it difficult to accurately and online evaluate the SSD depth. In the present research, incorporated with the probability statistics of the abrasive heights and the indentation fracture mechanics of the brittle material, a theoretical prediction model was established by investigating the inherent correlation between the measured cutting force of the diamond tool and the maximum depth of the subsurface cracks. Utilizing this predictive method, the SSD depth could be rapidly and precisely calculated through the mechanical properties of the material, the cutting force of the diamond tool, and the geometrical characteristics of the abrasives. To validate the feasibility of prediction technique, the experimental measurements of the maximum SSD depths were compared with the predicted results, revealing the acceptable consistency in their values. [ABSTRACT FROM AUTHOR]

Compared with conventional surface grinding (CSG) process, surface machining of carbon fiber-reinforced plastic (CFRP) composites using rotary ultrasonic machining (RUM) with vertical ultrasonic vibration generates smaller cutting forces because of improved machining performance and more damages to the machined CFRP surface due to the intermittent knocking induced by vertical ultrasonic vibration. It is reported that surface quality can be improved when the ultrasonic vibration is parallel to the feeding direction. In addition, elliptical ultrasonic vibration can be formed by the combination of horizontal and vertical ultrasonic vibrations. However, the effects of elliptical ultrasonic vibration in RUM surface machining of CFRPs are still unknown. This paper will study the influences of elliptical ultrasonic vibration on the machining performance and machined surface quality in RUM surface machining of CFRPs. The comparisons of output variables (including cutting forces, surface roughness, and machined surface topography) between RUM surface machining with elliptical ultrasonic vibration and the CSG process as well as RUM surface machining with vertical ultrasonic vibration will be conducted under different levels of input variables (including depth of cut, feedrate, and tool rotation speed). The abrasive-grain trajectory and the tool-workpiece contacting modes in these three machining processes are analyzed. It is found that RUM surface machining with elliptical ultrasonic vibration produced smallest feeding-direction cutting force, smallest vertical-direction cutting force, best morphology of machined surface, and smallest surface roughness among these three kinds of machining processes. [ABSTRACT FROM AUTHOR]

Longitudinal-torsional (L-T) vibration in rotary ultrasonic machining (RUM) can further reduce the cutting force and improve the machining efficiency compared with the single longitudinal vibration in RUM. In this study, an ultrasonic step horn with spiral slots using the principle of mode conversion was designed to realize L-T vibration. The torsional amplitude to longitudinal amplitude (AT/AL) ratio is proposed to quantify the efficiency of mode conversion. Moreover, a simulation method was used to carry out the frequency coupling design of the ultrasonic horn with spiral slots. The influence of the step position and slot position with a spiral angle of 52° on the resonant frequency and amplitude of the ultrasonic horn were analyzed, respectively. Based on the simulation results, ultrasonic horns with different AT/AL were designed and fabricated. Finally, the results obtained through experiments with milling glass plane revealed that the cutting force was reduced by 48–73%, while the surface quality improved compared with single longitudinal vibration when the torsional vibration is coupled with the longitudinal vibration in RUM. The reasonable AT/AL ratio could effectively reduce the cutting force when the synthetic amplitude was the same. This indicates that the L-T vibration changes the trajectories of the diamond abrasives, which improves the machining performance. [ABSTRACT FROM AUTHOR]

A giant magnetostrictive rotary ultrasonic machine tool (GMRUMT) with a large and stable amplitude output was developed. The purpose of this study was to comprehensively evaluate the performance and technological characteristics of the GMRUMT by conducting large amplitude experiments of rotary ultrasonic machining. Combined with the transducers' characteristic curves of vibration amplitude versus frequency, the GMRUMT has the advantages of greater amplitude, higher power, and better stability compared with the conventional piezoelectric actuated rotary ultrasonic machine tool. The vibration stability of the GMRUMT during the machining process was evaluated by carrying out the rotary ultrasonic face milling of quartz glass and the measurement of the actual ultrasonic amplitude. The processing performance of the GMRUMT was evaluated by obtaining the cutting force, the critical feed rate, and the edge-chipping size at the exit hole via rotary ultrasonic drilling experiments. The tool life was evaluated by observing the abrasive wear of the tool. Finally, the GMRUMT was studied in a stable amplitude output condition via tuning to verify the machining advantages of the GMRUMT. [ABSTRACT FROM AUTHOR]

The ultrasonic-assisted drilling (UAD) process is a technology that applies ultrasonic vibrations in the feed direction of the drill to improve drilling conditions and productivity. In recent years, UAD has been the subject of extensive research due to its advantages over the conventional drilling (CD) process, these being reported as thrust force and torque reduction, burr height reduction, improvements in surface roughness, and hole accuracy. The results of the research also showed that these benefits do not necessarily equally occur for all drilling conditions but can vary with machining and ultrasonic conditions. In particular, it is found that the drill vibration amplitude is a key factor in determining UAD benefits. However, a critical difficulty is that the all-important matter of the drill vibration amplitude at the point of material engagement, the so-called "down-the-hole" amplitude, is not known due to inaccessibility. This difficulty, not faced, for example by the ultrasonic-assisted turning (UAT) process due to its visual access, has prevented measurement of load effects on UAD, as well as verification of analytical models of the process. In this study, a technique to measure the effect of load on drill vibration amplitude during UAD is presented. The technique is based on examining the surface of the drilled hole, where minute, oscillatory traces of the vibrating drill tip are found that correspond to drill tip vibrational amplitude. This data, when coupled with in-process laser vibration measurements at the drill chuck, as well as no load amplitude measurements, permit the effects of load on vibration amplitude to be determined. Results have shown that drilling loads cause measurable reductions in drill vibration amplitude and must be accounted for in UAD procedures. [ABSTRACT FROM AUTHOR]

Micro-ultrasonic machining (MUSM) is an effective way of processing microstructures made from hard and brittle materials, although controlling the fluctuation of the machining force during processing is difficult. To control the quality of micro-holes fabricated in hard and brittle materials, MUSM with force control (MUSMFC) is used to study the edge chipping rate (ECR) and material removal rate (MRR) during micro-hole fabrication. The process is controlled using a force sensor and a processing control strategy. Various experiments are designed to assess the processing efficacy. Comparative experiments indicate that the ECR with MUSMFC is superior to that with traditional MUSM. Single-factor experiments show that the ultrasonic power and the fluctuation of the machining force exert a significant influence on the ECR. The influence of the spindle speed on the ECR is small. Orthogonal experiments show that the fluctuations of the machining force and ultrasonic power have large impacts on the MRR. The spindle speed has a significant impact on the MRR as well, whereas the mass fraction has little effect. The best combination of ECR and MRR is obtained using a spindle speed of 500 rpm, a machining-force fluctuation of 0.1 N, an ultrasonic power of 50 W, and a mass fraction of 10%. [ABSTRACT FROM AUTHOR]