Rotary Ultrasonic Machining Research Articles

Distributed capacitance effects on the transmission performance of contactless power transfer for rotary ultrasonic grinding

The contactless rotary transformer has been widely used in rotary ultrasonic machining because of less heat, less vibration, no friction and higher revolving speed. However, the power transfer efficiency of the rotary transformer is rather low. So it is necessary to adopt the method of capacitance compensation to maximum transfer efficiency, and more accurate compensation model will achieve better transmission performance. However, distributed capacitance existing in the primary and secondary winding current compensation models, which will seriously effect accuracy of capacitance compensation. In this study, a new mathematical model of four circuit compensation topologies is proposed, which takes distributed capacitance into consideration. Moreover, a series of experiments are conducted, which focus on the transmission efficiency and output power. The results of experiments have a good consistency with the new model and show higher accuracy compared with the previous models. In addition, the effect of distributed capacitance at different frequencies is also researched.

Rotary ultrasonic drilling of Ti6Al4V: Effects of machining parameters and tool diameter

This article presents the use of the rotary ultrasonic machining process for drilling holes in Ti6Al4V alloy which is regarded as a difficult-to-cut material due to its high-temperature strength and low thermal conductivity. This research presents an experimental investigation on the effect of the key rotary ultrasonic machining input parameters including ultrasonic power, spindle speed, feed rate, and the tool diameter on the main output responses including cutting force, hole cylindricity and overcut errors, and tool wear. No previous reports were found in literature to experimentally investigate the effect of the rotary ultrasonic machining parameters and the tool diameter on tool wear, surface integrity, and the accuracy of the drilled holes in Ti6Al4V alloy. The results showed that the rotary ultrasonic machining input parameters within the current ranges can significantly affect the quality of the drilled holes. Through proper selection of input parameters, holes could be drilled in Ti6Al4V alloy with smoothed surface morphology, low tool wear (0.7 mg) and very low cylindricity (2 µm) and overcut (120 µm) errors. Moreover, it was found that the selected level of any input parameter has the ability to significantly affect the influence of the other input parameters on the output responses.

A novel flexible tool with rotary ultrasonic spindle for fine grinding of tungsten carbide

Tungsten carbide is a typical difficult-to-cut material by conventional machining processes. In this paper, a novel design of flexible abrasives tool combined with a rotary ultrasonic machining (RUM) spindle is conducted to reduce the labor force significantly. The newly designed flexibility of tool-tip is aimed at preventing overcutting from the CNC grinding. The grinding conditions with resulted surface morphology of the tungsten steel were investigated through Taguchi design of experiment and ANOVA analysis. The machining capability of the novel flexible tool is compared with conventional tools through specific grinding paths under proper operational conditions.

A Chipping reduction approach in Rotary Ultrasonic Machining of Advance Ceramic

Machining of ceramic material is difficult to achieve with conventional machining methods. The rotary ultrasonic machine plays a crucial role in the machining of such harder materials. During machining of ceramics, the edge chipping is one of the crucial factors which affect the quality of the product. This factor must be at the lowest level of better quality and minimum wastage. This paper demonstrates the mechanism of fracture and effect of support length on edge chipping size during the experimental study of advance ceramic (Al2O3). The investigation results showed that edge quality can be improved by increasing the support length to the workpiece.

A study on the effect of main process parameters of rotary ultrasonic machining for drilling BK7 glass

BK7 glass is an important engineering material with extensive applications in high-quality and precision transmissive optical components. However, BK7 glass is considered to be a difficult-to-cut material due to its high brittleness and nonconductivity. This article presents the use of rotary ultrasonic machining process for drilling holes in BK7 glass. No previous reports have been found in the literature to experimentally investigate the response of the BK7 glass to rotary ultrasonic drilling. The experimental investigations take into account the effect of the key rotary ultrasonic machining input parameters including the ultrasonic power, spindle speed and feed rate on the output responses of cutting force, exit chipping, surface roughness, hole cylindricity and overcut errors, and surface integrity. The results show that the input parameters within the current ranges can significantly affect the quality of the drilled holes. Moreover, the selected level of any input parameter has the ability to significantly affect the influence of the other input parameters on the output responses. Through proper selection of input parameters, holes could be drilled in BK7 glass with less fractured topography, low surface roughness (1.32 µm), low exit chipping size (0.85), and very low cylindricity (3 µm) and overcut (73.6 µm) errors.

Enhancement of surface roughness for brittle material during rotary ultrasonic machining

Surface roughness is the key aspect which could increase the application of float glass by enhancing the machined hole quality. Glass is extensively used in microfluidic devices, bio-medical parts and biosensors. The core objective of the research study is to optimize the best parametric combination to achieve the least amount of surface roughness. The three major parameters which are used for designed experimental study are spindle speed, ultrasonic amplitude and feed rate. The least value of surface roughness is noticed at spindle speed (5000 rpm), vibration amplitude (20 μ m) and feed rate (6 mm/min) which be adopted for increasing its functional application. Consequently, after optimizing the parameters, least value of surface roughness at hole internal region is revealed as 1.09 μm.

Investigation of machining rate and roughness for rotary ultrasonic drilling of Inconel 718 alloy with slotted diamond metal bonded tool

Super alloy has extensive engineering applications in nuclear industries owing to its outstanding performance characteristics at elevated temperature. More than 30% of consumption in nuclear industries is super alloy. A number of holes are required to be drilled into super alloys for their final stage assembly. During conventional machining process, excessive heat is generated, which is the cause of heat treated zone that further affect the life and performance of the product. To overcome this difficulty, a rotary ultrasonic machining method came into existence to machine super alloys by hybrid cutting action (vibratory and rotary) of diamond impregnated core drill. This study focuses on the machining characteristics of super alloy by RUM process. The empirical modelling of process parameters of RUM is carried out for super alloy (Inconel 718) using an experimental design approach called response surface methodology. Material removal efficiency of RUM and surface topography of the machined material are studied. The results reported that for quality and productivity aspect, the feed rate in RUM is found a most critical factor. [Received 5 April 2017; Revised 10 June 2017; Accepted 26 June 2017]

Heterogeneous Feature Selection with an Application in Multi-Sensor- Based Condition Monitoring of a Tool Used In Rotary Ultrasonic Machining

Effective monitoring and diagnosis of tool wear condition plays a critical role in improving rotary ultrasonic machining quality and system reliability. In this study, force and vibration signals were first collected during rotary ultrasonic machining operation, next processed by time/frequency domain analysis or wavelet packet decomposition(WPD) for feature extraction, and then the best features are selected by a newly proposed heterogeneous feature selection method. Physical experiment data of the BK7 glass grinding process are implemented to evaluate the proposed method. The results were shown to illustrate the effectiveness of the proposed methods.

A study on the effects of machining variables in surface grinding of CFRP composites using rotary ultrasonic machining

Due to their excellent properties, carbon fiber-reinforced plastic (CFRP) composites are attractive in many industries, including aerospace, automobile, sports, etc. The structure of anisotropy and heterogeneity and the high abrasive resistance of carbon fibers make CFRPs difficult to cut in surface grinding processes. Many problems, including high cutting force, high tool wear, severe delamination, and high cutting temperature, are associated with conventional surface grinding processes. To reduce or eliminate these problems, surface grinding of CFRP composites using rotary ultrasonic machining (RUM) has been conducted. Machining variables play dominant roles in such a process. However, no investigations on effects of machining variables on output variables were reported. This paper, for the first time, reports effects of machining variables (ultrasonic power, tool rotation speed, feed rate, and depth of cut) on output variables (cutting force, torque, and surface roughness). The results revealed that the cutting force could be decreased by using higher level of ultrasonic power, higher level of tool rotation speed, lower level of feed rate, or lower level of depth of cut. Lower surface roughness could be achieved by a decrease of ultrasonic power, an increase of tool rotation speed, a decrease of feed rate, or a decrease of depth of cut. The machined CFRP surfaces’ morphology and the characteristics of damaged carbon fibers were, for the first time, analyzed and reported in such a process.

Surface grinding of CFRP composites using rotary ultrasonic machining: a comparison of workpiece machining orientations

The carbon fiber reinforced plastic (CFRP) composites have superior properties of high modulus-to-weight ratio, high strength-to-weight ratio, good durability, high corrosion resistance, and low thermal expansion coefficient. These properties make them attractive in many different applications, such as aerospace, medical, transportation, and sporting goods. However, CFRP’s properties of anisotropy, inhomogeneity, and abrasive properties of carbon fibers in CFRP composites generate many problems, including high cutting forces, high torque, delamination, high tool wear, decomposition of matrix material, etc., in traditional grinding processes. Surface grinding of CFRP composites using rotary ultrasonic machining (RUM) is used to decrease these problems. However, there is no investigation on effects of workpiece machining orientations in such a process. This investigation, for the first time, studies effects of workpiece machining orientations and machining variables (including tool rotation speed, feedrate, and ultrasonic power) on output variables (including both cutting force in feeding direction and cutting force in axial direction, torque, and surface roughness). The results show that lower cutting forces and torque are generated by using 90° workpiece machining orientation and lower surface roughness is produced by using 0° workpiece machining orientation. The results are discussed and analyzed, and they will fill in the research gaps in RUM surface grinding of CFRP composites.

Intermittent and Continuous Rotary Ultrasonic Machining of K9 Glass: An Experimental Investigation

Rotary ultrasonic machining (RUM) is a nontraditional and cost-effective machining method for hard and brittle materials, such as ceramics, optical glass, composite materials, and so on. RUM is a hybrid process that combines the material removal mechanisms of diamond abrasive grinding and ultrasonic machining. In RUM, a rotating cutting tool with metal-bonded diamond abrasive particles is ultrasonically vibrated in the axial direction while the tool spindle is fed toward the workpiece at a constant feedrate to remove material. It has been reported that continuous rotary ultrasonic machining has been successfully used to drill holes in K9 glass. Intermittent rotary ultrasonic machining is a newly introduced ultrasonic machining process, which uses a slotted cutting tool instead of a common metal bonded diamond cutting tool as used in continuous rotary ultrasonic machining. There has been no reported study to compare the effects of intermittent RUM and continuous RUM when machining K9 glass. This paper, for the first time, presents an experimental investigation to compare intermittent RUM and continuous RUM when machining K9 glass from the perspectives of cutting force, surface roughness, and chipping size.

Research into the transition of material removal mechanism for C/SiC in rotary ultrasonic face machining

Ceramic matrix composites of type C/SiC with superior properties have got increasing importance in many fields of industry, especially in the aerospace area. Rotary ultrasonic machining is a high-efficiency processing technology for these advanced materials. However, due to the inhomogeneity and anisotropy of these composites, the machining process is still challenging to achieve desired result due to the lack of understanding and control of material removal mechanism. In this paper, the maximum depth of penetration by diamond abrasives in workpiece material is proposed to quantify the material removal modes. A model of maximum depth of penetration for rotary ultrasonic face machining (RUFM) was developed based on the indentation theory. An experimental RUFM of C/SiC was carried out, and it revealed that the material removal mechanism transited from ductile mode to brittle fracture mode with the decrease of cutting speed. Similar transition was observed with the increase of feed rate and cutting depth. By comparing the measured cutting force with simulation, a critical depth of penetration for the cutting mechanism transition was defined at about 4 μm. The processed surface topography was studied, and the transition of material removal modes was identified by the sudden change of the 3D surface roughness map at the critical penetration depth. Thus, the maximum depth of penetration model developed in this paper can be applied to identify the ductile or brittle fracture removal mode in RUFM of C/SiC using the cutting parameters. This allows controlling the material removal mechanism to achieve desired machining efficiency and quality.

Analysis of Surface and Subsurface Damage Morphology in Rotary Ultrasonic Machining of BK7 Glass

This paper investigates the formation process of surface/subsurface damage in the rotary ultrasonic machining of BK7 glass. The results show that during the milling using the end face of the tool, the cutting depth and the residual height between the abrasive grains constantly change with the high-frequency vibration, generating lots of cracks on both sides of the scratches. The high-frequency vibration accelerates the chips falling from the surface, so that the chips and thermal damage are reduced, causing the grinding surface quality better. A plastic deformation area is formed during the grinding, due to the non-uniform cutting force on the material surface, and the residual stress is produced in the deformation area, inducing the median/lateral cracks.

Modeling and Testing on Material Removal Mechanism of Rotary Ultrasonic Machining

The technology of rotary ultrasonic machining is the combination of regular ultrasonic vibration and rotation motion. It applies a pre-load on the tool through tool head with an axial direction vibration and high rotation motion along with the ultrasonic system. The material removal mechanism of rotary ultrasonic machining, a model setup of efficiency on material removal and machining influence on different processing parameters are analyzed in this article. By comparing four different materials PZT Piezoelectric Ceramics, organic glass, glass steel and red cooper on single ultrasonic and rotary ultrasonic machining testing, the stabilization of machining process and efficiency of machining was analyzed on rotary ultrasonic machining as well. The testing proves that the rotation motion can significantly improve the ultrasonic machining efficiency on fracture toughness material.

Innovative Contactless Energy Transfer Accessory for Rotary Ultrasonic Machining and Its Circuit Compensation Based on Coil Turns

An innovative concentric rotary ultrasonic machining (RUM) device based on local induction is proposed. The device is used as a machine tool accessory that can add the RUM to any machining center. Rather than using a complete ring, a portion of a ring is used as the primary core in the proposed rotary transformer, which eliminates spindle speed limits. The simplified configuration provides increased safety and is convenient for material processing applications. Additionally, a circuit compensation method based on coil turns is proposed. It takes the whole circuit, reliability of electronic components, transmission efficiency, and output power into consideration. We use this method to choose the optimal number of coil turns and compensation elements required to achieve increased and safe power transmission performance. This paper also demonstrates the performance of the device through experimentation. Finally, practicability is discussed.

Experimental investigation of tool wear and machining rate in rotary ultrasonic machining of nickel alloy

ABSTRACTNickel alloys possess the excellent potential at high temperature and resistance to oxidation/corrosion owing to its high nickel content. These materials necessitate non-traditional machining methods. The rotary ultrasonic machining (RUM) process comes into existence as a superior alternative to the conventional machining of nickel alloys. The processing of these alloys using RUM needs attention. This article details the multi-response optimization in RUM of nickel alloy using the desirability concept. The present work is carried out with two shapes of the tool: (i) Plain tool and (ii) lateral slotted tool. During RUM, the process parameters—power rating tool rotation, abrasive diamond grit size and feed rate are varied. Compared with the plain tool, the lateral slotted tool shows the more efficient machining rate (MR) with less tool wear (TW). The micro-graphs disclose the mechanism of MR and TW during RUM.

Drilling High Precision Holes in Ti6Al4V Using Rotary Ultrasonic Machining and Uncertainties Underlying Cutting Force, Tool Wear, and Production Inaccuracies.

Ti6Al4V alloys are difficult-to-cut materials that have extensive applications in the automotive and aerospace industry. A great deal of effort has been made to develop and improve the machining operations of Ti6Al4V alloys. This paper presents an experimental study that systematically analyzes the effects of the machining conditions (ultrasonic power, feed rate, spindle speed, and tool diameter) on the performance parameters (cutting force, tool wear, overcut error, and cylindricity error), while drilling high precision holes on the workpiece made of Ti6Al4V alloys using rotary ultrasonic machining (RUM). Numerical results were obtained by conducting experiments following the design of an experiment procedure. The effects of the machining conditions on each performance parameter have been determined by constructing a set of possibility distributions (i.e., trapezoidal fuzzy numbers) from the experimental data. A possibility distribution is a probability-distribution-neural representation of uncertainty, and is effective in quantifying the uncertainty underlying physical quantities when there is a limited number of data points which is the case here. Lastly, the optimal machining conditions have been identified using these possibility distributions.

Cutting temperature and resulting influence on machining performance in rotary ultrasonic elliptical machining of thick CFRP

Abstract As a novel non-conventional machining process, rotary ultrasonic elliptical machining (RUEM) has been successfully used for drilling thick carbon fiber-reinforced plastics (CFRPs) recently. In order to reduce the thermal damage, the measurement of cutting temperature is important when RUEM of CFRP. In this research, the cutting temperatures in both RUEM and grinding drilling (GD) were measured by an infrared camera under dry condition. Temperature trends as functions of feed rate and cutting speed were obtained and the results showed that compared to GD, RUEM can effectively reduce the maximum temperature by 18.8% and 13.1% at the feed rate of 75 and 150 μm/rev respectively. Both mechanisms of temperature reduction and chip adhesion prevention in RUEM were analyzed. In addition, SEM observation of the machined surface revealed that better microstructure was obtained in RUEM compared to GD under the same cutting condition.

Optimization of rotary transformer for RUM with secondary self-compensation

In rotary ultrasonic machining (RUM), the rotary transformer can replace the well-established slip ring technology to supply contactless power for the revolving transducer. Such contactless energy transfer (CET) is safe and high rotation speed of the spindle is permissible. However, the transfer efficiency and output power are usually a pair of contradictions. In this paper, the self-compensation method is adopted on secondary side in order to improve the dynamic balance of the revolving part. Considering the distinct capacitive behavior of the transducer, two primary compensation topologies are given. The mathematical models are presented to identify the power transfer efficiency, transfer capability and load impedance of rotary transformer used in RUM. The effects of coil turns on transfer efficiency and load resistance are researched. An optimization method of rotary transformer used in RUM is put forward. A contactless power supply RUM system that can produce high speed, high efficiency and high output power is therefore possible.

Experimental study and optimization of cutting parameters in machining of super alloy with hybrid ultrasonic method

Super alloys are intensively used in various industries, especially in the aerospace industry, because of their special characteristics. A number of holes are sometimes required to be drilled into super alloys for aircraft at their final stage assembly. In the present study, a hybrid ultrasonic machining method, called rotary ultrasonic machining (RUM), was successfully used in super alloy drilling. The empirical modeling of the process parameters of RUM was performed for the super alloy (Inconel 718) using an experimental design approach, called response surface methodology (RSM). Parameters, namely tool rotation, feed rate, ultrasonic power, and abrasive grit size, were selected as input variables. The others were kept constant. The performance was measured in terms of the machining rate and the surface roughness. The developed models were found to be reliable representatives of the experimental results with prediction errors less than ±5%. Moreover, the feed rate for the quality and productivity aspect was found to be the most critical factor. The optimized values of the machining rate and the surface roughness achieved through a multi-response optimization were 0.9 825 mm3/s and 0.951 μm, respectively.