Ultrasonic Vibration-assisted Milling Research Articles

Theoretical Modeling and Surface Roughness Prediction of Microtextured Surfaces in Ultrasonic Vibration-Assisted Milling

Textured surfaces with certain micro/nano structures have been proven to possess some advanced functions, such as reducing friction, improving wear and increasing wettability. Accurate prediction of micro/nano surface textures is of great significance for the design, fabrication and application of functional textured surfaces. In this paper, based on the kinematic analysis of cutter teeth, the discretization of ultrasonic machining process, transformation method of coordinate systems and the cubic spline data interpolation, an integrated theoretical model was established to characterize the distribution and geometric features of micro textures on the surfaces machined by different types of ultrasonic vibration-assisted milling (UVAM). Based on the theoretical model, the effect of key process parameters (vibration directions, vibration dimensions, cutting parameters and vibration parameters) on tool trajectories and microtextured surface morphology in UVAM is investigated. Besides, the effect of phase difference on the elliptical shape in 2D/3D ultrasonic elliptical vibration-assisted milling (UEVAM) was analyzed. Compared to conventional numerical models, the method of the cubic spline data interpolation is applied to the simulation of microtextured surface morphology in UVAM, which is more suitable for characterizing the morphological features of microtextured surfaces than traditional methods due to the presence of numerous micro textures. The prediction of surface roughness indicates that the magnitude of ultrasonic amplitude in z-direction should be strictly limited in 1D rotary UVAM, 2D and 3D UEVAM due to the unfavorable effect of axial ultrasonic vibration on the surface quality. This study can provide theoretical guidance for the design and fabrication of microtextured surfaces in UVAM.

Design and surface analysis in large-amplitude longitudinal ultrasonic vibration-assisted milling of TC4 titanium alloy under dry conditions

Design and surface analysis in large-amplitude longitudinal ultrasonic vibration-assisted milling of TC4 titanium alloy under dry conditions

Effect of Duty Cycle on Cutting Force for Ultrasonic Vibration-Assisted Milling Carbon Fiber-Reinforced Polymer Laminates

Cutting force is an important factor that affects the surface quality of machining carbon fiber-reinforced polymer (CFRP). High cutting force can lead to surface damage such as the burrs and the delamination in the machining process of CFRP. Ultrasonic vibration-assisted machining (UVAM) can reduce the cutting force in the machining process. This work is focused on the relationship between the duty cycle and the cutting force in UVAM of CFRP. Based on the kinematics of UVAM, the movement of the cutting tool edge and the tool–workpiece separation in UVAM were analyzed, and a calculation formula for the duty cycle was obtained. The milling experiment of CFRP was conducted to compare the cutting force between UVAM and conventional machining (CM), and the relationship between the reduction in the cutting force in UVAM and the duty cycle was determined. The experimental results showed that when the duty cycle was 0.2916, the cutting force of UVAM was reduced by 7.4% to 27% compared with that of CM. When the duty cycle was 1, the cutting force of UVAM was reduced by −4.5% to 7.5% compared with that of CM. Therefore, the effect of reducing the cutting force of UVAM can be enhanced by adjusting the process parameters to reduce the duty cycle of UVAM, and a lower cutting force can be obtained.

Experimental Investigation on Axial Ultrasonic Vibration Assisted Milling of Cr12MoV

The conventional milling process is difficult due to the high strength and hardness of Cr12MoV, which can cause the rapid tool wear, premature failure,and poor milling quality of work platform. The ultrasonic vibration machining technology has been founded to be effective in the milling process of hard-to-cut materials like die tool steel and nickel alloys. The ultrasonic vibration assisted milling (UVM) technology is carried out the axial milling of Cr12MoV in this paper, and the average impact force Fi is influenced by the vibration amplitude A, the vibration frequency f, and equivalent mass of the vibrating part M. The mean value of cutting force Fx, Fy, and Fz decreases by 25%, 15.04%, and 17.46%, respectively. With the increase of vibration amplitudes, the value of surface roughness firstly decrease and then increase, and it is obviously lower than conventional milling. The experimental results demonstrated that the UVM technology is a feasible method for the low cutting force and high quality process of cutting Cr12MoV.

Investigating the material removal mechanism and cutting performance in ultrasonic vibration-assisted milling of carbon fibre reinforced thermoplastic

Carbon fibre reinforced thermoplastic (CFRTP) has emerged as a sustainable alternative to carbon fibre reinforced plastic (CFRP) due to its improved reparability and recyclability. CFRTP, particularly carbon fibre reinforced polyetheretherketone (CF/PEEK), is a high-performance material known for its excellent mechanical, thermal, and corrosion resistance properties, making it well-suited for extreme environments in civil aviation equipment. However, machining processes such as milling often result in defects due to the material’s high toughness and anisotropic nature. This study aims to investigate the material removal mechanism in ultrasonic-assisted milling (UAM) of CF/PEEK and compare the effects of fibre cutting angle (θ) and milling processes on milling performance. To simulate the fibre fracture mechanisms under different θ, finite element analysis (FEA) is employed. The results reveal different fracture modes, including bending, bending-shear, compression, and compression-shear, at various θ. Additionally, UAM demonstrates lower cutting forces and temperatures compared to conventional milling (CM). Notably, UAM greatly improves surface quality by reducing burr height and facilitating chip evacuation, while also enhancing surface integrity by minimizing cavity defects and fibre pull-out phenomena. These findings contribute to the development of low-damage machining methods that aim to achieve higher accuracy in CFRTP.

Analysis and modeling of cutting force considering the tool runout effect in longitudinal-torsional ultrasonic vibration-assisted 5 axis ball end milling

The longitudinal-torsional ultrasonic vibration-assisted milling (LTUVAM) can improve the machining quality compared with conventional milling (CM), and the machining quality is closely related to cutting force which is affected by the tool runout effect. In this study, a mechanistic force model for longitudinal-torsional ultrasonic vibration-assisted 5 axis ball end milling considering the tool runout effect is proposed. First, the cutting edge motion model considering the effects of tool runout and ultrasonic vibration is established. Then, based on the analysis of the cutting edge motion relative to the workpiece, the uncut chip thickness (UCT) is computed by means of the geometrical calculation method, and the engaged cutting edge elements are determined according to the Z-map method, the ultrasonic milling force model is established after determining the cutting force coefficients and tool runout parameters through calibration tests. Moreover, the impact of different parameters on dynamic separating characteristics of LTUVAM is studied by the tool-workpiece contact rate. Finally, the verification tests are carried out, and the experimental results show the effectiveness of the ultrasonic milling force model.

Stability analysis of TATWC based on UVA milling method

Difficult machining characteristics of titanium alloy materials and low rigidity characteristics of thin-walled component make Titanium Alloy Thin-Walled Component (TATWC) prone to chatter during machining, resulting in poor surface quality and other defects, which restricts the expansion and application of TATWC in the special industrial field. The appearance of Ultrasonic Vibration Assisted (UVA) milling method provides a new technology to overcome the processing problems of the TATWC. To analyze the stability of the TATWC processed by UVA milling method, first, by introducing a characterization function, a cutting force model of UVA milling method is established; The coefficients of cutting force between milling cutters and TATWC are solved through experiments. The model is verified by comparing the experimental and predicted values of cutting force; Secondly, the stability prediction model of UVA milling method based on full discrete method is established, and the effect of various process parameters on the stability of UVA milling method is researched. Finally, based on theoretical analysis, the modal characteristics of TATWC are measured through modal experiments. The feasibility of the stability prediction model of UVA milling method is verified by cutting TATWC with variable cutting depth.

Simulation and experimental study of ultrasonic vibration-assisted milling of GH4169 high-temperature alloy

GH4169 high-temperature alloy is widely used in aerospace and other fields because of its excellent fatigue, radiation, oxidation, and corrosion resistance. However, milling forces, high temperatures, and machining hardening can occur during milling processing. To explore the machining characteristics of GH4169 high-temperature alloy, an ultrasonic vibration-assisted milling model was established to study the effect of ultrasonic milling parameters on the milling process. The simulation results show that: the increase of ultrasonic amplitude can effectively reduce the machining stress, improve the chip-breaking effect and reduce the milling force; with the rise of milling speed, the separation characteristic is weakened, which is not conducive to chip breaking; the increase of radial cutting width will increase the machining stress and improve the milling force. Finally, by comparing the actual machining and simulation results, the error is within 10%, which verifies the feasibility of the simulation study and provides guidance for ultrasonic milling of GH4169 high-temperature alloy.

Ultrasonic constitutive model and its application in ultrasonic vibration-assisted milling Ti3Al intermetallics

Ultrasonic vibration-assisted technology is widely utilized in the performance research and manufacturing process of metallic materials owing to its advantages of introducing high-frequency acoustic systems. However, the acoustic plasticity constitutive model and potential mechanism, involving Ti3Al intermetallic compounds, have not yet been clarified. Therefore, the Ultrasonic-K-M hybrid acoustic constitutive model of Ti3Al was established by considering the stress superposition, acoustic thermal softening, acoustic softening and acoustic residual hardening effects according to the dislocation density evolution theory and crystal plasticity theory. Meanwhile, the mechanical behavior of ultrasonic vibration-assisted tension (UVAT) and microstructure of ultrasonic vibration-assisted milling (UVAM) for Ti3Al was investigated. Dislocation density to be overcome from initial deformation to failure of Ti3Al was calculated in UVAT and was verified in UVAM. The results indicated that the Ultrasonic-K-M model showed a good agreement with the experimental data. There was an obviously softening phenomenon after introducing the ultrasonic energy field in the Ti3Al whole deformation region, and the degree of softening was positively correlated with amplitude. Furthermore, the maximum reduction ratio in yield strength of Ti3Al was 16 % and the maximum reduction value in ultimate tensile strength was 206.91 MPa. The elongation rose first and then fell as amplitude enlarged, but only as the vibration was applied in the whole deformation region, the elongation was always greater than 14.58 %. In addition, The UVAM process significantly reduced the dislocation density increment to be overcome for Ti3Al material removal by 1.37 times, and promoted dislocation motion and cancellation to make twisted dislocations evolve into parallel dislocations. As the amplitude increased to 4 μm, the depth of the disturbed area of the plastic deformation layer increased by a maximum of 2.5 times.

An innovative study on high-performance milling of carbon fiber reinforced plastic by combining ultrasonic vibration assistance and optimized tool structures

At present, the aviation industry puts forward higher requirements for high-performance milling technology of carbon fiber reinforced plastic (CFRP). This paper proposed a sharpening milling CFRP strategy by combining of ultrasonic vibration and optimized tool structure of fluted burr tools. The sharpening cutting mechanisms of the ultrasonic vibration and tool structure were analyzed theoretically first. Next, the milling performance of optimized fluted burr tool was verified compared with conventional helical end mill and the results showed the optimized tool structure had positive effects on damage suppression and surface roughness. On this basis, Ultrasonic vibration-assisted milling (UVM) with the optimized fluted burr tool was applied to further improve the machined surface quality of T800 CFRP. The verification experimental results showed that, compared to conventional milling, both the cutting force and cutting temperature were significantly reduced in UVM, with a maximum decrement of 39.7% and 15.7% respectively. Besides, the surface defects were significantly suppressed and the surface roughness was reduced by 11.4%–37.6% in UVM. The results of this paper suggested that the combination of UVM and optimized fluted burr tool was an efficient and low damages milling strategy for CFRP.

Design of Longitudinal-Torsional Transducer and Directivity Analysis during Ultrasonic Vibration-Assisted Milling of Honeycomb Aramid Material.

This paper presents a longitudinal-torsional transducer for use during the ultrasonic vibration-assisted milling (UVAM) of honeycomb aramid material. The mechanism of longitudinal-torsional conversion was analyzed to guide the design of a vibration transducer. The transducer features five spiral grooves around the front cover plate, which function under the excitation of a group of longitudinal piezoelectric ceramics. A portion of the longitudinal vibration was successfully converted into torsional vibration. The resonant frequency, longitudinal vibration displacement and torsional amplitude at the top of the disk milling cutter were 24,609 Hz, 19 μm and 9 μm, respectively. In addition, the directivity of the longitudinal-torsional transducer was theoretically analyzed. Compared with conventional milling, UVAM with the longitudinal-torsional could significantly reduce the cutting force (40-50%) and improve the machining stability.

Enhanced dry machinability of TC4 titanium alloy by longitudinal-bending hybrid ultrasonic vibration-assisted milling

While cutting fluids are widely used in industrial mechanical machining of difficult-to-cut materials, achieving environmentally-friendly dry milling without the usage of cutting fluids by utilizing advanced manufacturing techniques makes significant sense for facilitating cleaner production. In the present work, we demonstrate the feasibility of enhancing dry machinability of TC4 titanium alloy by applying the newly proposed longitudinal-bending hybrid ultrasonic vibration-assisted milling (LBVAM), which is effective in modulating the intermittent cutting behavior between tool and workpiece material. Specifically, the kinematics and the material removal mechanisms of the LBVAM are investigated by analytical investigation, 3D finite element simulations and corresponding experiments. Simulation and experimental results demonstrate that the utilization of LBVAM enables lowering the surface roughness by 46.7% and reducing the cutting force by 43.2% from conventional milling. And the mostly prominent feature is that the surface roughness can be down to 100 nm by using the proposed LBVAM with rationally selected parameters, which is highly promising for realizing cleaner dry manufacturing of TC4 without using cutting fluids. Current work provides a feasible environmentally-friendly machining method for enhancing the dry machinability of difficult-to-cut materials.

The processing parameters optimization of UVAM-processed CuNiAl alloy based on surface integrity parameters

The surface integrity of a material has a significant impact on fretting wear performance. Based on the analysis of the material surface integrity, the machining parameters were optimized to obtain the best fretting wear performance of CuNiAl alloy. First, the effects of ultrasonic vibration-assisted milling (UVAM) processing parameters on the surface integrity of CuNiAl alloy were studied. Consequently, the relationship between UVAM processing parameters and CuNiAl alloy surface integrity parameters was established through the optimized support vector machine (PSO-SVM) model. The relationship between the surface integrity parameters, processing parameters, and fretting wear performance was established. The best fretting wear performance was obtained at a spindle speed of 147.4 m/min, feed rate of 76 mm/min, and vibration current of 199.5 mA.

Surface and subsurface analysis of TC18 titanium alloy subject to longitudinal-torsional ultrasonic vibration-assisted end milling

Longitudinal-torsional ultrasonic vibration-assisted milling is a machining method that can effectively improve the quality of the machined surface. When this method is used for the end milling of TC18 titanium alloy, however, the law of influence on the machined surface and subsurface remains unclear. In this study, we examined the effects of the ultrasonic amplitude, feed rate, and cutting speed on the machined surface morphology, roughness, surface residual stress, and subsurface microstructure in the longitudinal-torsional ultrasonic vibration-assisted end-milling process. According to the results, longitudinal-torsional ultrasonic vibration-assisted end milling can help form more obvious surface microtextures with a more distinct surface texture regularity at large amplitude, small feed rate, and high cutting speed. Compared with conventional milling, longitudinal-torsional ultrasonic vibration-assisted milling generates a larger roughness and surface residual stress and a deeper plastic deformation layer of the subsurface in the case of an obvious highly perturbed layer. In addition, the surface residual stress becomes greater and the plastic deformation layer gets deeper at a larger amplitude. When the amplitude was 5 µm, the surface residual stress was − 450.625 MPa and the depth of the deformation layer was 5.4 µm. The stress and depth increased by 21.55 % and 134.78 %, respectively, compared with those of conventional milling. The increase in the feed rate enhanced the roughness, decreased the surface residual stress, and did not significantly alter the depth of the plastic deformation layer. When the feed rate was 0.01 mm/z, the roughness was 0.383 µm and the surface residual stress was − 479.1 MPa. The feed rate and roughness increased by 42.63 % and 20.62 %, respectively, compared with those of conventional milling. With the increase in the cutting speed, the roughness increased, and the surface residual stress and the depth of the plastic deformation layer decreased. When the cutting speed was 15 m/min, the roughness was 0.31 µm, the surface residual stress value was − 454.7 MPa, and the depth of the plastic deformation layer was 5.7 µm. These three parameters increased by 17.8 %, 18.79 %, and 92.5 %, respectively, compared with those of conventional milling. This research has certain application prospect in surface machining of titanium alloy and quality control of machined surface.

Generation mechanism of surface micro-texture in axial ultrasonic vibration-assisted milling (AUVAM)

Although axial ultrasonic vibration-assisted milling (AUVAM) is promising for rapid and economical fabrication of 3D micro-texture on various surfaces, it has been a challenge to obtain micro-texture with small feature size and large height simultaneously. The mechanism and major influence factors for the formation of micro-texture by this method were explored in this study. It was found that the generation of micro-texture was mainly caused by cutting and extrusion from the flank face of the milling tool under ultrasonic vibration. Therefore, a novel 3D tool model that considered the relief angle, end cutting edge angle and the blade profile was established in simulation analysis. The good agreement between simulation and experimental results demonstrated that the influence of the flank face on the micro-texture was mainly attributed to the relief angle of the milling tool. It was the first time to report that both the height and the profile shape of the micro-texture unit were affected by the overlap and extrusion between the flank surface and the micro-texture. But this influence diminished with the increase of spindle speed. 3D sinusoid-shaped micro-texture with minimum width of 20 μm and height of 2 μm (fully reproduced the ultrasonic amplitude) was realized with the relief angle of 40° and spindle speed of 4000 rpm. Other typical textures of weave, shell, scale and corrugation were also presented to show the effective regulation of texture patterns in AUVAM. This work provides both theoretical and practical basis for such a low-cost, efficient and controllable 3D micro-texture preparation method.

Surface quality and milling force of SiCp/Al ceramic for ultrasonic vibration-assisted milling

Due to the advantages of higher specific stiffness, wear resistance, and thermal conductivity, SiCp/Al ceramics are widely used in aerospace, automation, and other industries. As a novel machining method, ultrasonic vibration-assisted milling (UVAM) can efficiently perform the milling of difficult-to-machine materials such as SiCp/Al ceramics. In this study, the contact ratio model of tool-chip is established for UVAM. Based on the presented contact ratio model, the effect of processing parameters on the contact ratio is analyzed. The microscopic model of SiCp/Al ceramic is developed by FEM simulation, which takes into account the distribution of the reinforcement particles and the internal structure of SiCp/Al ceramic. According to the simulation results, the material removal mechanism of SiCp/Al ceramic is investigated. The theoretical and experimental analysis shows that the material removal of SiCp/Al ceramic mainly consists of plastic removal of the Al matrix, the fracture of the reinforcement phase, and the debonding of the interfacial phase. Since the effect of intermittent cutting, UVAM can effectively suppress the generation of surface defects compared to conventional milling.

Investigation of deviation and surface topography in ultrasonic vibration-assisted milling

Thin-walled structures have many applications in the aerospace industry. An important feature of them is their high strength to weight. When milling the thin-walled part, the thickness decreases step by step by cutting, which causes the process to be complex and dependent on process parameters. In the present study, thin-walled aluminum structures are investigated using conventional and ultrasonic milling processes, and distortion, surface roughness, surface texture, and average thin-wall forces are also investigated. Therefore, 18 tests are performed on parts made of 7075T6 aluminum alloy using various feeds, spindle speeds, and machining modes. The results showed that the machining type and spindle speed had 47% and 33% effect on distortion, respectively. In addition, the results showed that by applying vibrations to the milling, the amount of distortion can be reduced by up to 30% and effectively optimized. This technique is suitable for manufacturing industries that require high dimensional accuracy. Also, the surface texture and burr formation are investigated. In particular, the surface roughness in ultrasonic milling decreased compared to conventional milling.

AN INVESTIGATION OF ULTRASONIC VIBRATIONS EFFECT ON SURFACE ROUGHNESS IN ALUMINUM 7075 AND AISI 1045 CARBON STEEL DURING END MILLING AND SIDE MILLING OPERATION

Milling is one of the discontinuous machining methods which makes tools contact with workpiece continuously along with the regular change of shear force. Providing strong materials for fabricating the required pieces challenge machining and producing complex shapes. Therefore, operations intended for reducing machining forces as well as increasing the final surface smoothness are remarkably important of which using ultrasonic vibrations is one method. This study centers on ultrasonic vibration-assisted milling operation. The required ultrasonic vibrations are applied using a transducer to an AISI 1045 steel workpiece and a 7075 aluminum. Also, by using an arithmetic modal analysis simulation on the related workpiece and fixture, the designing process was performed in a way to equate the natural frequency of the whole set to that of the ultrasonic transducer. The resonant frequency obtained for the steel and aluminum workpieces was 19840 and 19757[Formula: see text]Hz, respectively, and the milling operation was done by applying ultrasonic vibrations to the workpiece. The results obtained from surface roughness measurement indicated that an increase in the ultrasonic intensity from 15[Formula: see text]W/cm2 to 22.5[Formula: see text]W/cm2 in the aluminum workpiece resulted in improved surface roughness ([Formula: see text] by 70%. In addition, an increase in the ultrasonic intensity from 15[Formula: see text]W/cm2 to 22.5[Formula: see text]W/cm2 improved the surface smoothness ([Formula: see text] by 72%. Moreover, concerning the steel workpiece while the tool is perpendicular to the direction ahead of the workpiece, it was clear that applying 22.5[Formula: see text]W/cm2 ultrasonic vibrations to the end-milled surfaces resulted in an approximate increase in the average and maximum surface smoothness by 53% and 45%, respectively. Furthermore, applying 30[Formula: see text]W/cm2 ultrasonic vibrations to face-milled surfaces, either perpendicular to or parallel to the tool, led to an approximate increase in the average and maximum surface smoothness by 35% and 25%, respectively.

Numerical and experimental study on the amplitude effect of ultrasonic vibration-assisted milling of 3D needle-punched Cf/SiC composite

The anisotropy, heterogeneity, and high hardness of Cf/SiC composite bring great difficulties to its efficient and high-quality processing. Ultrasonic vibration-assisted milling (UVAM) has been shown to positively affect the machining quality of Cf/SiC. This work focuses on the effect of ultrasonic amplitude on 3D needle-punched Cf/SiC composites machining under different fiber cutting angles, and few related studies have been reported. By analyzing the simplified cutting model for both forward and reverse cutting, the influence of ultrasonic amplitude on tool-fiber contact characteristics was investigated. Under fiber cutting angles of 0°, 45°, 90°, and 135°, finite element simulations based on the orthogonal cutting model and UVAM experiments with different amplitudes were performed. The results showed that the alternating friction force caused by the harmonic vibration promoted the damaging effect of the tool on the fiber and SiC matrix. At 0° and 135°, localized fiber failure occurred early. And at 45° and 90°, the shear failure of the fiber was strengthened, which alleviated the damage to the low-strength matrix and the interface layer. Compared with conventional milling, the resultant force showed a downward trend, and typical defects such as pits, fiber pullout, matrix voids, and interface debonding on the machined surface were suppressed in UVAM. As the amplitude increased, the machined surface became smoother, and the surface roughness Sa at all angles decreased by more than 30%. According to the response surface method, the influence order of machining parameters on Sa was obtained: feed rate > amplitude > cutting speed. Sa predictive regression model with only a 5% deviation from the experimental value has good accuracy and reliability. This work shows that reasonable control of ultrasonic parameters and fiber cutting angle in UVAM significantly affects the machining quality improvement of 3D needle-punched Cf/SiC components.

Z-map based cutting force prediction for elliptical ultrasonic vibration-assisted milling process

Elliptical ultrasonic vibration-assisted milling (EUVAM) adds high-frequency vibration to conventional milling (CM) to realize high-frequency intermittent milling. It has broad application prospects in the processing of difficult-to-cut materials such as titanium alloys, superalloys, and hard and brittle materials. To reveal the mechanism of the highly intermittent cutting nature in EUVAM, according to the motion relationship between the cutting edge and the workpiece and the Z-map representation of the workpiece, a method and its algorithm for calculating the undeformed cutting thickness and thus the cutting force in EUVAM are proposed. The simulation results show that EUVAM can improve the actual cutting speed when compared with CM, and the proportion of idle cutting time will directly determine the intermittent degree of the milling process. The experiment of EUVAM is performed to verify the correctness of the proposed cutting force model, and the impact of spindle speed on the cutting force in EUVAM is also analyzed. It is shown that UEVAM can reduce the cutting force by up to 50% under appropriate cutting conditions.