Ultrasonic Vibration-assisted Grinding Research Articles

Vibration coupling effects and machining behavior of ultrasonic vibration plate device for creep-feed grinding of Inconel 718 nickel-based superalloy

Ultrasonic vibration-assisted grinding (UVAG) is an effective and promising method for machining of hard-to-cut materials. This article proposed an ultrasonic vibration plate device enabling the longitudinal full-wave and transverse half-wave (L2T1) vibration mode for UVAG. The characteristics of two-dimensional coupled vibration in different directions were analyzed on the basis of apparent elastic method and finite element method. Furthermore, a correction factor was applied to correct the frequency error caused by the apparent elastic method. Finally, the comparative experiments between the conventional creep-feed grinding and UVAG of Inconel 718 nickel-based superalloy were carried out. The results indicate that the apparent elastic method with the correction factor is accurate for the design of plate device under the L2T1 vibration mode. Compared with the conventional creep-feed grinding, the UVAG causes the reduction of grinding force and the improvement of machined surface quality of Inconel 718 nickel-based superalloy. Furthermore, under the current experimental conditions, the optimal ultrasonic vibration amplitude is determined as 6 μm, with which the minimum surface roughness is achieved.

Grinding characteristics during ultrasonic vibration assisted grinding of alumina ceramic in selected dry and MQL conditions

Ultrasonic vibration assisted grinding (UAG) has proven to lower the forces and improve the ground surface quality while shaping difficult to grind materials such as ceramics. A systematic study of UAG of alumina ceramic using a metal bonded diamond grinding wheel has been performed here. Taguchi’s L18 array based experimentation has been performed to study the effect of UAG parameters. During UAG, the vibration amplitudes of 6 and 12 microns have been used and the frequency has been kept at 20 kHz. From these experiments, optimum parameters for UAG have been identified using Grey relational analysis. Mathematical models generated using regression analysis have been found to correlate the experimental data with good accuracy. A comparison of the grinding forces and roughness of the surfaces generated in dry and minimum quantity lubrication (MQL) conditions in both conventional grinding and optimal condition in UAG has been performed to identify the beneficial effects of providing vibration to the workpiece. The surface quality has been evaluated using 3D roughness data, 3D plots and SEM images of the ground surface. By examining nature of the ground surface and kurtosis (Sku) values of the surface profile, it has been concluded that UAG reduces brittle fracture and facilitates material removal by ductile mode for alumina. The desired condition of least machining forces and highest surface quality has been achieved during the combination of UAG and MQL.

Surface texture formation mechanism based on the ultrasonic vibration-assisted grinding process

It is widely accepted that surface textures can significantly improve the tribological properties of surfaces. The purpose of this research was to study surface texture formation mechanism through the ultrasonic vibration-assisted grinding process. First, a single grain cutting process model was established, and the cutting trajectory length and shape were calculated. Second, the single grain profile models were established that considered the dressing effect. Then, by considering continuous cutting process of large amounts of grains, the surface texture formation mechanism model was established. The calculation results were verified by experiments. Finally, the characteristic parameters that described the surface texture topography were proposed and the influence law of the process parameters was analyzed. The results of this research showed that the established theoretical model could accurately describe the ultrasonic vibration-assisted grinding process and the topographical characteristics of the surface texture. By controlling the process parameters, surface textures with controllable topography could be processed. This work can provide a substantially theoretical basis for processing surface textures efficiently.

Development and performance of a novel ultrasonic vibration plate sonotrode for grinding

Abstract Compared with Conventional Grinding (CG), the Ultrasonic Vibration-Assisted Grinding (UVAG) is more competitive for the machining of difficult-to-cut materials. In this article, a novel ultrasonic vibration plate sonotrode that enables the special longitudinal full-wave and transverse half-wave vibration modes was proposed. The vibration characteristics of the proposed sonotrode was theoretically studied based on the apparent elasticity and Rayleigh methods, achieving a single longitudinal workpiece ultrasonic vibration with an amplitude of 7.6 μm. A superior vibration uniformity was achieved, as indicated by the coupling coefficient of 0.5. Based on the proposed method, the normal and tangential grinding forces decreased by 35 % and 39 % in comparison with the CG, and an improved machined surface was obtained in the UVAG of Ti-6Al-4V, with the following characteristics: vibration amplification of 7.6 μm; a cut depth of 0.1 mm; a workpiece feed rate of 100 mm/min; and a grinding speed of 30 m/s.

Research on Material Removal Mechanism of C/SiC Composites in Ultrasound Vibration-Assisted Grinding.

C/SiC composites are the preferred materials for hot-end structures and other important components of aerospace vehicles. It is important to reveal the material removal mechanism of ultrasound vibration-assisted grinding for realizing low damage and high efficiency processing of C/SiC composites. In this paper, a single abrasive particle ultrasound vibration cutting test was carried out. The failure modes of SiC matrix and carbon fiber under ordinary cutting and ultrasound cutting conditions were observed and analyzed. With the help of ultrasonic energy, compared with ordinary cutting, under the conditions of ultrasonic vibration-assisted grinding, the grinding force is reduced to varying degrees, and the maximum reduction ratio reaches about 60%, which means that ultrasonic vibration is beneficial to reduce the grinding force. With the observation of cutting debris, it is found that the size of debris is not much affected by the with ultrasound vibration. Thus, the ultrasound vibration-assisted grinding method is an effective method to achieve low damage and high efficiency processing of C/SiC composites.

Surface morphology evaluation of multi-angle 2D ultrasonic vibration integrated with nanofluid minimum quantity lubrication grinding

Nanofluid minimum quantity lubrication (NMQL) is an emerging cleaner and sustainable technique. However, the effective immersion of nanofluids in the grinding zone in NMQL grinding limits the extensive application of this technique. Ultrasonic vibration can exert a pumping effect that injects nanofluids into the interface between the grinding wheel and workpiece. Furthermore, technique integration benefits the infiltration state transition of micro-droplets. However, evaluation of the coupling effect and surface morphology of multi-angle 2D ultrasonic vibration integrated with NMQL has rarely been performed. This study aims to address these research limitations. A kinematics model was developed, and the grain and workpiece relative motion trails in 2D ultrasonic vibration-assisted grinding (UVAG) were simulated at different resultant vibration angles (θ). The grain’s cutting characteristics were then analyzed and found to be conducive to the full infiltration of nanofluids into the grinding zone. Moreover, the surface characterization of multi-angle 2D UVAG coupled with NMQL was evaluated experimentally. Results showed that the optimal θ was achieved at 45° due to the differential cutting action of the follow-up grain. NMQL obtained a better result than flooding at the same θ. When the gain effect of the coupling techniques was reflected in surface roughness, the Ra value decreased by 19.5 % (compared with UVAG) and 39.9 % (compared with NMQL). The autocorrelation function curves presented periodic and continuous local oscillations under the grinding conditions of 2D UVAG with θ = 45° and θ = 135°.

Mechanism study on ultrasonic vibration assisted face grinding of Hard and brittle materials

Ultrasonic vibration assisted face grinding (UAFG) has excellent performance in hard and brittle materials processing. In order to reveal the surface generating mechanism and improve the machining quality, this study was dealing with investigation on ultrasonic energy distribution and surface generating characteristics. Based on the modeling of grinding force, surface generation and material removal volume, the grinding mechanism of UAFG is analyzed and presented in detail. The surface generating process is described by grain trajectory interference and overlap, and the grinding force model is established based on fracture mechanics of brittle materials. According to the mathematical modeling, an innovation for surface adjustment and grinding force calculation in UAFG is proposed. Depend on the theoretical study, the combined effect of ultrasonic vibration and processing parameters on grinding force and surface micro structure in UAFG is reported. The surface characteristics can be designed and simulated by process parameter optimization; high performance surface can be achieved due to the theoretical calculation. The correctness of the theoretical derivation is verified by numerical calculation and comparative experiments. This investigation can be used as a basic principle for machining surface improvement and processing technology modification in UAFG.

Effect to the Surface Composition in Ultrasonic Vibration-Assisted Grinding of BK7 Optical Glass

Because of the changes in cutting conditions and ultrasonic vibration status, the proportion of multiple material removal modes are of uncertainty and complexity in ultrasonic vibration-assisted grinding of optical glass. Knowledge of the effect of machined surface composition is the basis for better understanding the influence mechanisms of surface roughness, and also is the key to control the surface composition and surface quality. In the present work, 32 sets of experiments of ultrasonic vibration-assisted grinding of BK7 optical glass were carried out, the machined surface morphologies were observed, and the influence law of machining parameters on the proportion of different material removal was investigated. Based on the above research, the effect of surface composition was briefly summarized. The results indicated that the increasing of spindle rotation speed, the decreasing of feed rate and grinding depth can improve the proportion of ductile removal. The introduction of ultrasonic vibration can highly restrain the powdering removal, and increase the proportion of ductile removal. Grinding depth has a dominant positive effect on the surface roughness, whereas the spindle rotation speed and ultrasonic amplitude both have negative effect, which was caused by the reduction of brittle fracture removal.

Drilling of cemented carbide by ultrasonic vibration-assisted grinding on a flexible stage

Drilling of cemented carbide by ultrasonic vibration-assisted grinding on a flexible stage

Visualization of Stress Distribution by Photoelastic Method Under Ultrasonic Grinding Condition

This study investigates phenomena in ultrasonic vibration-assisted grinding. The appropriateness of a stress visualization method is proven through comparison of a Hertzian contact stress analysis using finite element methods. The stress distribution on soda-lime glass caused by a 3-mm-diameter diamond electro-deposited wheel is visualized using a photo-elasticity method. The study compares the local stress concentrations caused by grains with and without ultrasonic wheel vibration. The global reaction force is measured by a dynamometer. The ultrasonic vibration leads to a reduced fluctuation of force, as well as a reduced time-averaged force. It is thought that the ultrasonic vibration causes a smaller local stress beneath the grains, which generates chips. In contrast, typical photo-elasticity methods are applicable for plane stress conditions. However, the stress distribution in a workpiece under a face grinding condition is distributed three-dimensionally, and the stress distribution cannot be recognized directly from the phase difference. Assuming that the stress distribution is sufficiently stable in a wheel rotation, continuously-captured images can be reconstructed to produce a 3D stress distribution, using computed tomography. The experimental tomographic images show a spatially-dispersed phase difference image caused by the electro-deposited wheel, with several discontinuous diamond grains on the end face of the wheel.

Ultrasonic vibration-assisted grinding of blind holes and internal threads in cemented carbides

Cemented carbides are widely used in aerospace and mechanical processing industries due to their excellent physical and chemical properties. However, cemented carbide products processed by conventional methods have such deficiencies as poor surface integrity, high surface roughness, and high consumables. Given this, a method for machining blind holes and internal threads in cemented carbide by ultrasonic vibration-assisted grinding is introduced in this paper. The methodology combines ultrasonic-assisted grinding with helical mill-grinding to machine cemented carbide via a diamond form grinding wheel. Based on the characteristics of ultrasonic longitudinal-torsional vibration, the motion trajectories of individual abrasive particles under conventional grinding (Con-G) and ultrasonic longitudinal-torsional vibration-assisted grinding (ULTVAG) were analyzed. Tests were conducted to investigate the influence of machining parameters on the grinding force, hole surface quality, thread profile accuracy, and wear conditions of the two diamond form grinding wheels. The results obtained strongly indicate that ULTVAG can reduce the grinding force, while the grinding force is mostly controlled by the feed rate and is less affected by the spindle speed and ultrasonic vibration amplitude (UVA). With an increase in UVA, the hole surface roughness exhibits first decreasing and then rising. The optimal hole surface quality is observed at the longitudinal ultrasonic vibration amplitude A = 4 μm. At too high values of UVA, the hole surface quality becomes worse than that acquired via the conventional grinding. The first few threads machined by Con-G and ULTVAG are shown to meet the requirements of 6H precision of thread. As the number of processed threads increases, the wheel of Con-G becomes severely worn, resulting in insufficient machining precision. The number of threads machined by a single grinding wheel under ULTVAG is higher than that of Con-G. It is proved that ULTVAG with an appropriate UVA can reduce the wear of grinding wheel and prolong its service life, as well as improve the thread precision and qualified rate.

Feasibility of Ultrasonic Vibration Assisted Grinding for Carbon Fiber Reinforced Polymer with Monolayer Brazed Grinding Tools

Ultrasonic vibration assisted grinding (UVAG) is an effective method for edge trimming to improve the mechanical integrity of carbon fiber reinforced polymer (CFRP). However, due to the high heat resistance, abrasiveness and powdery chip of CFRP, serious tool clogging, rapid tool wear and poor surface are still considerable problems to the industry. In this paper, monolayer brazed diamond grinding tools with defined grain distribution are designed in order to solve the above problems. The maximum undeformed chip thickness based on UVAG was analyzed. A mathematical grinding force model was established based on monolayer brazed diamond tools. The UVAG experiments using different grain inter-row spacing diamond tools were carried out. The grinding force and surface morphology were investigated and compared. It was found that the predicted grinding force values were consistent with the experimental results. Additionally, the force was strongly related to the grain inter-row spacing. When employing the tool with the grain inter-row spacing of 1.2 mm, the grinding force was highest and the roughness of the surface was better due to more active grits and interaction-overlap areas.

Investigation of Indentation Zone on K9 Glass under Ultrasonic Vibration Condition Using an Equivalent Mean Contact Pressure

Ultrasonic vibration-assisted grinding (UVAG) is a promising processing method for parts made of hard-brittle material, as a green machining. The material removal mechanism of hard-brittle material in UVAG is not yet fully understood. The mean contact pressure in the mechanical model of material deformation/fracture that is induced by abrasive grit reveals the deformation/fracture level during the material removal of the indentation of hard-brittle material. To investigate the material removal mechanism of K9 glass in UVAG, a new variable, namely, the equivalent mean contact pressure (EMCP) of glass indentation under ultrasonic vibration was proposed as a corresponding variable for mean contact pressure. A series of indentation experiments with/without ultrasonic vibration was carried out to analyze the material fracture of glass as induced by single random-shaped diamond grits. To obtain the EMCP, an equivalent characteristic size of ultrasonic vibration indentation of K9 glass was defined and measured in the experiments. The vertical load, EMCP and the profile features of the indentation zone, such as the equivalent characteristic size and indentation depth, were investigated in the indentation experiments. Subsurface damage of the K9 glass was also investigated by using UVAG and traditional grinding experiments to analyze the significance of the EMCP on material fracture during machining. The experimental results show the EMCP correlated better with the subsurface damage from UVAG than vertical load. Therefore, compared with the load, the EMCP is a better variable to reveal the difference of material removal mechanism between the UVAG and traditional grinding of glasses.

Investigation on grinding temperature in ultrasonic vibration-assisted grinding of zirconia ceramics

The feasibility of ultrasonic vibration-assisted grinding (UVAG) in machining brittle materials, such as zirconia ceramics, has been preliminarily proved. The high temperature generated in grinding processes is a main factor responsible for thermal and surface/subsurface damage. However, there are few reports about grinding temperature for zirconia ceramics by UVAG. In this study, a grinding force model is used for the analysis of grinding temperature in UVAG based on kinematic principle of ultrasonic vibration and brittle material fracture removal mechanism. Then, the heat fluxes equation during grinding process is analyzed. And the grinding temperature model is developed based on theoretical grinding force model and heat fluxes. Finally, pilot experiments are carried out to analyze influence of vibration parameters and process parameters on UVAG temperature and verify the mathematical model. The comparison results show that ultrasonic vibration has an important influence on grinding temperature with the reduction of 10.6%. In addition, there is a good consistency between mathematical model and the experimental results. The average relative error is within 10%. Therefore, the mathematical model could be used to predict the UVAG temperature.

A comprehensive investigation of surface generation and material removal characteristics in ultrasonic vibration assisted grinding

Ultrasonic vibration assisted grinding (UVAG) has been proved to be superior in improved machining quality and reduced surface roughness compared with conventional grinding (CG), but its mechanism is still in constant research and understanding. Except for the imposed axial vibration, another much smaller radial vibration is generated due to Poisson effect at the same time, which has different effect on the surface generation. In this paper, a comprehensive simulation model of UVAG considering Poisson effect has been developed to predict the three-dimensional surface topography and calculate the parameters (undeformed chip thickness, dynamic active grain number) which could reflect the characteristics of corresponding material removal process. The comparison between experimental results and simulated results shows that the method proposed in this paper is in good agreement with the experimental results. The imposed axial vibration can increase dynamic active grain number, generate uniform undeformed chip thickness and reduce the surface roughness, while the additional radial vibration causes the fluctuation of undeformed chip thickness and the increase of surface roughness. The proposed simulation model of UVAG provides a new approach to the prediction of the ultrasonic surface topography and understanding of material removal process as well as the optimization of the UVAG.

Investigation of surface topography formation mechanism based on abrasive-workpiece contact rate model in tangential ultrasonic vibration-assisted CBN grinding of ZrO2 ceramics

Ultrasonic vibration-assisted grinding is widely used as a highly efficient processing method for hard-and-brittle materials such as zirconia ceramic materials. Based on the characteristics of ultrasonic vibration assisted intermittent machining, combined with the motion characteristics of the single abrasive particles and adjacent abrasive particles, the abrasive grain-workpiece contact rate model between abrasive particles and workpieces during ultrasonic vibration assisted grinding is proposed. The grinding force, surface quality and the life of the grinding head are directly affected during the machining process. In the ultrasonic vibration assisted grinding process, the non-periodic distribution of the contact and separation between the grinding head and the workpiece is reflected, which increases the complexity of analysis in the ultrasonic vibration assisted grinding process. According to the model, the influence of machining factors (cutting speed) and vibration factors (amplitude, frequency) on the contact rate is analyzed. In addition, a contrast experiment is designed to analyze the surface morphology between ultrasonic vibration assisted grinding and common grinding. And the surface quality is effectively improved by using ultrasonic vibration. Besides, a four-level and four-factor orthogonal experiment is designed. The surface roughness prediction model is established on the basis of the neural network of genetic algorithm, and the validity of the model is verified by the experiment.

The grinding force modeling and experimental study of ZrO2 ceramic materials in ultrasonic vibration assisted grinding

As an advanced structural ceramic, zirconia ceramics are gradually used in the fields of manufacturing, aerospace and other fields with their excellent properties. However, the mechanism of material removal is complex for zirconia ceramics but it is generally accepted that the brittle-and-hard material is removed by plastic removal and brittle removal. In this paper, ultrasonic vibration assisted grinding is used as non-traditional processing to machine the ceramic materials. Firstly, a single abrasive grain scratch test was first carried out on the ZrO2 ceramic materials. It can be obtained through experimental analysis that the removal mode of the zirconia ceramic material is changed with the increase of load. When the applied load is greater than 500 mN, the zirconia ceramic materials are removed by brittle removal. Then, based on analysis of scratch test and kinematics of ultrasonic vibration assisted grinding (UVAG), a grinding force prediction model is developed and the validity of the model is verified by the experiment designed. It can be found that the grinding force is decreased with the increase of spindle speed (n) and amplitude (Aa). And the grinding force is increased with the increase of feed rate (vf) and grinding depth (ap). In addition, compared with the grinding force of the common grinding (CG), the grinding force is significantly reduced in the UVAG. And the surface quality of the workpiece is improved and the wear of the grinding head is reduced in the UVAG by the analysis of experiment.

Ultrasonic vibration-assisted microgrinding of glassy carbon

Glassy carbon is an amorphous material which, due to its unique material properties, has recently been introduced to micro/nanoimprinting as mold substrates. However, since glassy carbon is a hard, brittle, and highly elastic material, the precision machining of micro/nanostructures on it remains a challenging task. In this research, ultrasonic vibration-assisted microgrinding was proposed for ductile machining of glassy carbon. To find suitable conditions, the effects of ultrasonic vibration assistance and tool inclination were investigated. The results showed that by utilizing ultrasonic vibration assistance and tool inclination, a ductile response was achieved with improved surface roughness. In addition, the periodical waviness of the groove edge due to material elastic recovery was successfully prevented. This study provided an insight into the kinematics in ultrasonic vibration-assisted grinding of a highly elastic, hard, and brittle material.

Estimation of Energy and Time Savings in Optical Glass Manufacturing When Using Ultrasonic Vibration-Assisted Grinding

Energy and time savings are highly important aspects of green manufacturing. Ultrasonic vibration-assisted grinding (UVAG) is a high-efficiency, low-energy-consumption processing method for optical components made from hard and brittle materials. This work presents an experimental investigation of the specific grinding energy and the subsurface damage depth in UVAG of optical glasses to estimate the increased energy and time savings produced when using UVAG in optical glass manufacturing. The normal and tangential grinding forces of traditional grinding (TG) and axial UVAG processes on optical glasses were investigated for various machining parameters. The specific grinding energies during the TG and UVAG of the optical glasses were calculated and analyzed from the perspective of the energy consumption of the grinding process. The subsurface damage depths in optical glass during TG and UVAG were measured as an estimate of the machining quality, and the magnetorheological polishing spot method was used to analyze the time saved in subsequent polishing processes. The results show that UVAG can reduce energy consumption during the grinding of glass and produce significant time savings in subsequent polishing processes. The UVAG process therefore shows good potential for use in green manufacturing of optical components.

3D surface roughness evaluation of surface topography in ultrasonic vibration assisted end grinding of SiCp/Al composites

3D surface roughness evaluation of surface topography in ultrasonic vibration assisted end grinding of SiCp/Al composites