Ultrasonic Machining Research Articles

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.

Microstructure Transformation and Refinement Mechanism of Undercooled Cu-Ni-Co Alloy Based on Simulation of Critical Cutting Speed in Ultrasonic Machining

Microstructure Transformation and Refinement Mechanism of Undercooled Cu-Ni-Co Alloy Based on Simulation of Critical Cutting Speed in Ultrasonic Machining

Research on ultrasonic assisted press-fit assembly of small interference fits

Interference fits are widely used in aerospace, precision instruments and other fields. Press-fit assembly is one of the traditional assembly methods for interference fitting parts. Wear during assembly will affect the performance of interference components and the service life of marine equipment. Ultrasonic assisted press-fit can significantly reduce the press-mounting force of an interference fit. However, its effect on connection quality is rarely studied. The mechanism of ultrasonic assisted press-fit is unclear. In this paper, ultrasonic assisted press-fit was simulated and experimentally studied. The effects of ultrasonic vibration on heat generation, press-mounting force, connection strength, and interface wear were analyzed and discussed. Through analogy analysis with similar ultrasonic assisted machining processes, the mechanism of ultrasonic assisted press-fit was revealed. The results show that the superimposed ultrasonic vibration can effectively reduce the joining force (up to 33.5%), and increase the connection coefficient from 10% to 40%. This is due to stress superposition, friction reduction and acoustic softening that reduces interface wear. The increase of the interface roughness Rz from 3.681 to 4.586 μm confirms this analysis. Furthermore, the ultrasonic vibration can effectively reduce the material plastic flow of contact interface. This study reveals the significant advantages of ultrasonic assisted press-fit assembly (UAPA) method and provided a basis to understand the underlying mechanisms of UAPA.

An Experimental Study on Ultrasonic Vibration-Assisted Turning of Aluminum Alloy 6061 with Vegetable Oil-Based Nanofluid Minimum Quantity Lubrication

Minimum quantity lubrication (MQL) is a potential technology for reducing the consumption of cutting fluids in machining processes. However, there is a need for further improvement in its lubrication and cooling properties. Nanofluid MQL (NMQL) and ultrasonic vibration-assisted machining are both effective methods of enhancing MQL. To achieve an optimal result, this work presents a new method of combining nanofluid MQL with ultrasonic vibration assistance in a turning process. Comparative experimental studies were conducted for two types of turning processes of aluminum alloy 6061, including conventional turning (CT) and ultrasonic vibration-assisted turning (UVAT). For each turning process, five types of lubricating methods were applied, including dry, MQL, nanofluid MQL with graphene nanosheets (GN-MQL), nanofluid MQL with diamond nanoparticles (DN-MQL), and nanofluid MQL with a diamond/graphene hybrid (GN+DN-MQL). A specific cutting energy and areal surface roughness were adopted to evaluate the machinability. The results show that the new method can further improve the machining performance by reducing the specific cutting energy and areal surface roughness, compared with the NMQL turning process and UVAT process. The diamond nanoparticles are easy to embed on the workpiece surface under the UVAT process, which can increase the specific cutting energy and Sa as compared to the MQL method. The graphene nanosheets can produce the interlayer shear effect and be squeezed into the workpiece, thus reducing the specific cutting energy. The results provide a new way for the development of eco-friendly machining.

On understanding the cutting mechanism of SiCp/Al composites during ultrasonic elliptical vibration-assisted machining

SiCp/Al composites play a significant role in achieving equipment lightweight, but its mechanical properties weaken the machinability. Ultrasonic elliptical vibration-assisted machining (UEVM) is a potential way to improve the machinability of difficult-to-cut materials, provides an efficient and precise solution for SiCp/Al composites in industrial manufacturing. However, the removal mechanism of SiCp/Al composites during UEVM and the effective guidance for practical machining are rarely investigated. In this paper, the cutting mechanism of SiCp/Al during UEVM is analyzed through theoretical analysis, finite element (FE) simulation and systematic experiments. Specifically, a multi-phase 2D microscopic FE simulation model is implemented and verified through systematically scratching tests. The research results indicate that particle stress distribution is influenced by variable tool-particle relative position during UEVM, promoting particle fracture and forming high-density zone of broken particles. Segmented chips with shorter length and greater curvature are the main form during UEVM, and dense layered structure appears on free surface of chips. Surface defects include cavities, crushing particles and scratches, while subsurface damage is dominated by pits and crack invasion. In addition, removal rate affects the surface formation, especially under very low scratching speed. Higher scratching speed weakens the ability of particle crushing under vibration effect, which is not helpful for improving surface integrity. Therefore, a reasonable cutting speed of 200 mm/min should be set during UEVM. This paper brings in a deeply understanding on cutting mechanisms of SiCp/Al composites, provides a theoretical guidance for the design and optimization of the vibration assisted processing of metal matrix composite.

Design of Compensation Network and Parameter Optimization for Rotary Ultrasonic Machining Under Varying Loads

Design of Compensation Network and Parameter Optimization for Rotary Ultrasonic Machining Under Varying Loads

Research on the machining mechanism of AISI 304 ultrasonic vibration assisted grinding

Compared with conventional grinding (CG), ultrasonic vibration assisted grinding (UVAG) has more prospects and competitiveness in processing AISI 304. Due to the change of strength of materials, when the vibration is superimposed on the workpiece, the mechanism of ultrasonic assisted machining is different from that of tool ultrasonic assisted machining. Therefore, this article proposes a workpiece vibration grinding device suitable for UVAG to study the corresponding grinding mechanism. The vibration characteristics of workpiece ultrasonic generator were discussed based on finite element simulation and the vibration situation of the device was tested with instruments to verify the accuracy of the simulation. Meanwhile, the machining mechanism of workpiece ultrasonic vibration was studied through grinding comparative experiments. The experiment showed that the displacement curve of the output end of the ultrasonic vibration of AISI 304 with time could be approximated to a sine wave and there was no other clutter. As the amplitude percentage of the ultrasonic generator increased, the output amplitude of the transducer showed an increasing trend. The ultrasonic amplitude and the amplitude percentage of ultrasonic generator approximately follow a linear relationship. The grinding force decreased with the increase of spindle speed and amplitude, and increased with the increase of feed rate and grinding depth. Compared with conventional grinding force, the grinding force of tangential ultrasonic vibration assisted grinding (TUVAG) decreased by about 29 %, while the grinding force of radial ultrasonic vibration assisted grinding (RUVAG) decreased by about 28 %. Under the action of ultrasound, the workpiece obtained better surface morphology. Under processing conditions of vw = 25 mm/min, ap = 0.01 mm, n = 2000r/min, A = 8 μm, f = 20000 Hz, the minimum surface roughness Ra of TUVAG is 0.51, followed by RUVAG with Ra = 1.02, while the surface roughness Ra of CG is the worst at 1.56 due to grinding burns.

Biological Activities of Citrus aurantium Leaf Extract by Optimized Ultrasound-Assisted Extraction

Several studies have explored the biological activities of Citrus aurantium flowers, fruits, and seeds, but the bioactivity of C. aurantium leaves, which are treated as waste, remains unclear. Thus, this study developed a pilot-scale ultrasonic-assisted extraction process using the Box–Behnken design (BBD) for the optimized extraction of active compounds from C. aurantium leaves, and their antityrosinase, antioxidant, antiaging, and antimicrobial activities were evaluated. Under optimal conditions in a 150× scaleup configuration (a 30 L ultrasonic machine) of a pilot plant, the total phenolic content was 69.09 mg gallic acid equivalent/g dry weight, which was slightly lower (3.17%) than the theoretical value. The half maximal inhibitory concentration of C. aurantium leaf extract (CALE) for 2,2-diphenyl-1-picrylhydrazyl–scavenging, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)–scavenging, antityrosinase, anticollagenase, antielastase and anti-matrix metalloprotein-1 activities were 123.5, 58.5, 181.3, 196.4, 216.3, and 326.4 mg/L, respectively. Moreover, the minimal inhibitory concentrations for bacteria and fungi were 150–350 and 500 mg/L, respectively. In total, 17 active compounds were detected in CALE—with linalool, linalyl acetate, limonene, and α-terpineol having the highest concentrations. Finally, the overall transdermal absorption and permeation efficiency of CALE was 95.9%. In conclusion, our CALE demonstrated potential whitening, antioxidant, antiaging, and antimicrobial activities; it was also nontoxic and easily absorbed into the skin as well as inexpensive to produce. Therefore, it has potential applications in various industries.

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.

Selected Aspects of Precision Machining on CNC Machine Tools

The work is new due to the type of process used—ultrasonic precision machining—to determine the possible effect of spindle heating (long-term machining) on the precision of the flat surface. It was carried out on a precise ultrasonic machining machine, and the material of workpiece was ceramic Al2O3. A flat surface was machined. Such an experiment has not been feasible until now. The experiment was divided into two days. On the first day, the machining time was 4 h. It is a long enough time to create a temperature-steady state. On the second day, with a cold tool and cold machine tool, we continued where we left off on the first day. This is how we monitored the accuracy of the dimensions of the workpiece on the plane surface. We have achieved the following: The average interface depth achieved values of 0.007089 mm and 0.003667 mm for cold and heated spindles, respectively. It means that when the spindle is not heated, the depth of the interface is higher by 93% (almost double the depth). The average standard deviation of the interface depth is 0.001683 mm and 0.000997 mm for cold and heated spindles, respectively. It means that when the spindle is not heated, the process is not as stable, and the standard deviation is higher by 69%.

Longitudinal-torsional coupled rotary ultrasonic machining end surface grinding of SiCf/SiC composites: a mechanical model of cutting force

Longitudinal-torsional coupled rotary ultrasonic machining end surface grinding of SiCf/SiC composites: a mechanical model of cutting force

Multi Objective Parametric Optimization of Ultrasonic Vibration Assisted Turning on TI6AL4V Alloy

The industrial and engineering applications of Titanium alloys has increased in the recent times particularly in automobile and aerospace industries. Ultrasonic machining of titanium alloys is one of the developments in the recent times to counter the poor machinability characteristics of Ti alloys. In this work, ultrasonic vibration assisted turning is adopted in machining Ti6AL4V with cutting speed, feed rate, depth of cut and amplitude as process parameters. Cutting force, cutting temperature and surface roughness are considered as performance evaluators. The role of each process parameter on each of the responses is evaluated and the optimum parametric combination for multi objective optimization is determined using Grey Relational Analysis. The results are interpreted with respect to tool work contact ratio. It was concluded from the experimental analysis that cutting force, cutting temperature and surface roughness depend on the TWCR which in turn depends on cutting speed and amplitude of vibration. Low TWCR revealed better performance whereas the effect of ultrasonic vibration is found to be reduced with increment in TWCR. In addition, feed rate and depth of cut are found to be significant in effecting the multi response characteristic (GRG).

A machine learning study on the fatigue crack path of short crack on an α titanium alloy.

In the present study, a physics-informed neural network model based on Bayesian hyperparameter optimization is proposed for the prediction of short crack growth paths. A large number of cyclic loadings at a lower amplitude were applied to an α titanium sample by an ultrasonic fatigue machine to ensure a sufficient amount of data for machine learning. The grain size, grain orientation and grain boundary direction on the path, as well as crack growth direction, were selected as feature data for training the prediction model. The optimizations of the size ratio and the angle operation were conducted to compare different data processing methods, respectively. After evaluation, eventually, a model for predicting crack growth path is obtained with a reliable performance of 10% tolerance on the path angle at each grain boundary. And the prediction effect of the proposed model is better than that of some classic machine learning models and slip trace analysis. This article is part of the theme issue 'Physics-informed machine learning and its structural integrity applications (Part 1)'.

Surface fractures in pre-crystallized and crystallized zirconia-containing lithium silicate glass-ceramics generated in ultrasonic vibration-assisted machining

Machining-induced surface fractures in ceramic restorations is a long-standing problem in dentistry, affecting the restorations’ functionality and reliability. This study approached a novel ultrasonic vibration-assisted machining technique to zirconia-containing lithium silicate glass-ceramics (ZLS) and characterized its induced surface fracture topographies and morphologies to understand the microstructure-property-processing relations. The materials were processed using a digitally controlled ultrasonic milling machine at a harmonic vibration frequency with different amplitudes. Machining-induced surface fracture topographies were measured with a 3D white light optical profilometer using the arithmetic mean, peak and valley, and maximum heights, as well as the kurtosis and skewness height distributions, and the texture aspect ratios. Fracture morphologies were analysed using scanning electron microscopy (SEM). The surface fracture topographies were significantly dependent on the material microstructure, the mechanical properties, and the ultrasonic machining vibration amplitudes. Larger scale fractures with higher arithmetic mean, peak and valley heights, and kurtosis and skewness height distributions were induced in higher brittleness indexed pre-crystallized ZLS than lower indexed crystallized ZLS by conventional machining. Conchoidal fractures occurred in pre-crystallized ZLS while microcracks were found in crystallized state although brittle fractures mixed with localized ductile flow deformations dominated all machined ZLS surfaces. Ultrasonic machining at an ideal vibration amplitude resulted in more ductile removal, reducing fractured-induced peaks and valleys for both materials than conventional processing. This research demonstrates the microstructure-property-processing interdependence for ZLS materials and the novel machining technique to be superior to current processing, reducing fractures in the materials and potentially advancing dental CAD/CAM techniques.

Experimental study on ultrasonic vibration assisted grinding of GCr15SiMn bearing steel

Many problems of GCr15SiMn high-carbon chromium bearing steel have been found in the ordinary grinding (OG) process. Aiming at the problems of high grinding force, low residual compressive stress and low surface quality, ultrasonic machining technology is combined with OG. The test of ultrasonic vibration assisted grinding (UVAG) GCr15SiMn high carbon chromium bearing steel is carried out. The residual stress, surface roughness, grinding force, and surface morphology are analyzed by changing machining parameters. The research showed that as the grinding depth and feed speed become larger, the grinding force increased, when the spindle speed rises, the grinding force becomes smaller. In the test range, with the ultrasonic amplitude from small to large, the grinding force from large to small. The ultrasonic grinding force is 27.8% lower than that of OG. The surface roughness increases with increasing grinding depth and feed speed and decreases with increasing spindle speed and ultrasonic amplitude, and at an amplitude of 6 μm, the surface roughness is reduced by 27% compared to OG. When the feed speed and grinding depth are lowered or the ultrasonic amplitude is increased, the surface residual compressive stress is increased. Compared to OG, it is increased by more than 13.5% under the same parameters. At the same time, the phenomenon of burrs and surface tears can be reduced, and the surface quality of the workpiece becomes better.

Notch effect in very high-cycle fatigue behaviour of a structural steel

The presence of a notch or a detail which leads to stress concentration due to complex geometries has a considerable impact on the fatigue life of engineering structures. Therefore, on the one hand, the notch effect must be investigated and considered in the fatigue assessment of these structures. On the other hand, in the last decades, an interest in studying the very high-cycle fatigue regime (VHCF) has been perceived, due to the extension of the service life of engineering components beyond the 10 million cycles. Thus, the notch effect in the VHCF regime was analysed for the S690 structural steel. Therefore, an analytical approach to design notch specimens was developed and a numerical simulation was performed to assess it. Then, an experimental campaign with smooth and notched specimens with two different stress concentration factors was performed in an ultrasonic fatigue machine to assess the VHCF behaviour. The mechanisms of failure and fracture surfaces were also investigated. It was observed a fully notch sensitivity as well as the dominance of surface crack initiation for the S690 steel in the VHCF regime.

Surface integrity of Nomex honeycomb composites after ultrasonic vibration machining by using disc cutters

Surface integrity has been widely used in metals machining, while the quality of Nomex honeycomb composites (NHCs) is yet troubled in selecting a proper indicator. In this study, surface integrity was introduced to evaluate machined NHCs with a proposed method named mark cell comparison along with other indicators, such as width of white belt, depth of subsurface damage and fractal dimension. The influence of ultrasonic amplitude on surface integrity was analyzed, suggesting an optimal amplitude. Based on the results, the feasibility and necessity to employ a set of quantitative indicators of surface integrity were discussed and demonstrated.

Loss-based structures and frequency dependencies of giant magnetostrictive materials for rotary ultrasonic machining applications

Loss-based structures and frequency dependencies of giant magnetostrictive materials for rotary ultrasonic machining applications

Optimization of assembly devices of automated workplaces using the TRIZ methodology

Abstract The presented article familiarizes the reader with optimizing the workplaces of ultrasonic welding machines. The essential part of the article deals with prototypes, the construction of which does not meet the requirements for production, economy, and functionality. The experimental analysis runs pointed out shortcomings and inaccuracies. The developer’s team used one of the well-known optimization and design methods to solve this issue. It is the TRIZ method (Creating and solving creative assignments). The mentioned method combines two powerful tools into one whole. Specifically, it is the Function and Cost Analysis (FNA) and the algorithm for solving creative assignments (ARIZ). The manuscript describes the use of the method for a more straightforward solution to problematic parts of the structure. The result of the optimization process is a new, improved structure whose properties were confirmed in terms of stiffness by simulation in the ANSYS Workbench program. The applications of optimized parts will also be used in other similar devices. The research will follow up with the design of a new series of ultrasonic welding machines in the future.

Very High Cycle Fatigue and Ultrasonic Testing in Multiaxial Loading

Abstract Fatigue damage has special relevance on the lifespan of mechanical components and structures, as it takes responsibility for the majority of registered structural failures. Most fatigue testing today still uses uniaxial loads, nonetheless it is generally recognized that multiaxial stresses occur in many full-scale structures. Nowadays, the growing need for greater lifespans forced the study of material behavior under what is nowadays very high cycle fatigue (VHCF) regime, fatigue research beyond 10E07 up to 10E10 cycles. However, most classic fatigue machines are often very costly, both in terms of time and energy, for such an elevated number of cycles. The high costs of equipment and time to conduct such experiments have seen a massive improvement with the introduction of high frequency ultrasonic machines. Presently, it is already possible to characterize materials VHCF response under axial and multiaxial loading conditions in a fraction of the time. Ultrasonic testing machines were first introduced for simpler uniaxial loading and more recently adapted for multiaxial loading conditions. The present work reviews the current background of ultrasonic fatigue testing machines working at 20-kHz frequency, with emphasis on multiaxial fatigue and VHCF. A review of a series of fatigue tests are presented, respectively, axial, shear, axial/shear, and in-plane bi-axial fatigue tests with different combining dimension specimens allowing different shear/axial stress ratios. Special attention will be put into the performance of multiaxial classical cylindrical specimens under tension/torsion and flat cruciform specimens under in-plane bi-axial testing using low-cost piezoelectric transducers. By comparing all so far developed and successfully reached multiaxial specimens and respective methodologies, two base approaches were possible to be established. When designing new specimens or ultrasonic machines, or both, one of the two methods must be followed. To have a well-comprehended methodology and successful design approach will undoubtedly guide future multiaxial ultrasonic method ideas.