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Precision ultrasonic machining process: A case study of stress analysis of ceramic (Al2O3)
Abstract
Recent study and development activity in the field of precision ultrasonic machining (USM) process has focused on the ceramic (Al2O3). This paper first analyzes the USM process, mechanism, dynamics, and trends. It then discusses, in detail, the USM process applications on the ceramic (Al2O3).
... Large grit size produce inadequate flow at the machining zone [2,4]. Through several investigation, it conclude that 30% slurry concentration gives optimum MRR for any type of material [5,6]. Most-effective carrier medium is water as compared to glycerol, kerosene oil, benzene and vegetable oil [4][5][6]. ...
... Through several investigation, it conclude that 30% slurry concentration gives optimum MRR for any type of material [5,6]. Most-effective carrier medium is water as compared to glycerol, kerosene oil, benzene and vegetable oil [4][5][6]. Appropriate flow rate also improve the MRR [7]. Recirculation of fresh abrasive slurry can overcome the contamination and blockage type resistance [5]. ...
... Appropriate flow rate also improve the MRR [7]. Recirculation of fresh abrasive slurry can overcome the contamination and blockage type resistance [5]. For sodalime glass, boron carbide abrasive gives 15-20% more MRR as compare to silicon carbide abrasive [4,5]. ...
Purpose
Polycarbonate bullet proof (UL-752) glass is highly demanded material in automobile, aerospace and space industries. It is also used in security chambers or buildings, because of its unique properties such as; impact bare capacity, hardness, excellent transparency, higher mechanical strength, good dimensional stability etc. Objective of this research investigation is focused at studying the impact of different input parameters (concentration, abrasive, power rating, grit size, HF acid concentration and tool material) on output responses (material removal rate, tool wear rate and surface roughness) in ultrasonic drilling of polycarbonate bullet proof (UL-752) glass.
Design/methodology/approach
The experiments have been performed by using Taguchi’s L27 orthogonal array and grey relation analysis has been used for the optimization of multiple responses. To find out the significant factors, analysis of variance is further employed.
Abbreviation
CUSM: Chemical assisted ultrasonic machining; PBPG: Polycarbonate bullet proof glassHF: Hydrofluoric; MRR: Material removal rate; TWR: Tool wear rate; SR: Surface roughness; DOE: Design of experiment; DOF: Degree of freedom; OA: Orthogonal array; GRA: Grey relation analysis; GRC: Grey relation coefficient; GRG: Grey relation grade; S/N: Signal to noise ratio; ANOVA: Analysis of variance; RSM: Response surface analysis; SEM: Scanning electron microscope
... Another researcher stated that when the tensile stresses generated during machining it increased the load over the workpiece peripehery. and furthermore lateral cracks and chipping propagate in the work sample surface (Ghahramani and Wang, 2001). Nath et al. (2012) stated that the mechanism behind the hole entrance chipping has been due to sliding action and angle of penetration during ultrasonic machining. ...
... In a past article, it was mentioned that when the von Mises stress reached the tensile strength of the workpiece sample, chipping of nearby edges were assumed to be initiated (Xu and Zhang, 2015). The maximum amount of tensile stress was generated along 30 axis on both sides of the impact axis (Ghahramani and Wang, 2001). In case of multi-shape tools, the angle of impact on the workpiece surface vary, consequently, it could affect the chipping quantity. ...
... It was stated that shear force is always maximum at the outer region and minimum or negligible near neutral axis. Also, in a research study, it was stated that the maximum amount of shear stress was observed at 45 from the axis where impact force happened (Ghahramani and Wang, 2001). The reason behind the occurrence of chipping in each tool case is described as follows. ...
Float glass has immense applications such as sensor glass, micro-processor glass and decorative glass; because of its exceptional wear resistance, chemical and thermal characteristics. Nevertheless, researchers are still bearing decisive issues, which affect its application. These issues are profile inaccuracy and chipping because of its poor machining characteristics and hence high precision machining. The objective of the present study is to condemn the chipping related hindrances while using multi-shaped diamond abrasive tools to create blind holes. The tools, which applied, are named as hollow abrasive tool, pinpointed conical tool, flat cylindrical tools and concave circular tool. The experimental trials were performed by rotary ultrasonic drilling (RUD) and CNC conventional drilling (CD). The actual industrial conditions and parameters were considered throughout the experimentation. Physics behind the formation of chipping on hole periphery by RUD and CD are revealed. In addition, individual mechanisms of multi-shape tools with respect to chipping are analyzed. The results show that RUD process has attained the smallest measurement of chip radial distance as compared to CD for all types of tool. Finally, the concave circular tool is found as the best tool particularly to get least chip radial distance during drilling i.e. 0.1145 mm.
... The history of USM started since 1927 with a research paper reported by A.L. Loomis and R.W. Wood (Jain and Jain, 2001; Ghahramani and Wang, 2001;Jain, 2013;Kumar, 2013). American engineer Lewis Balamuth in 1945 was granted first patent for his work on USM (Gilmore, 1991;Jain and Jain, 2001; Ghahramani and Wang, 2001;Jain, 2013). ...
... The history of USM started since 1927 with a research paper reported by A.L. Loomis and R.W. Wood (Jain and Jain, 2001; Ghahramani and Wang, 2001;Jain, 2013;Kumar, 2013). American engineer Lewis Balamuth in 1945 was granted first patent for his work on USM (Gilmore, 1991;Jain and Jain, 2001; Ghahramani and Wang, 2001;Jain, 2013). USM processes can be classified as ultrasonic drilling, ultrasonic cutting, ultrasonic abrasive and ultrasonic dimensional machining (Jain and Jain, 2001; Azarhoushang and Akbari, 2007;Dvivedi and Kumar, 2007). ...
... In USM process, power supply has an important role. It converts low frequency electrical signals into high frequency electrical signals (Goetze, 1956;Hong and Hung, 1956;Weller, 1984; Jain and Jain, 2013; Ghahramani and Wang, 2001;Rao et al., 2010;Kumar, 2013). Then, these signals are transmitted to transducer. ...
Purpose
This review paper reveals the literature on ultrasonic, chemical-assisted ultrasonic and rotary ultrasonic machining of glass material. The objective of the review paper is to understand and describe the working principle, mechanism of material removal, experimental investigation, applications and influence of input parameters on machining characteristics. The literature reveals that the ultrasonic machines have been generally preferred for the glass and brittle work materials. Some other non-traditional machining processes may thermally damage the work surface. Through these ultrasonic machining, neither thermal effects nor residual stresses have been generated on the machined surface.
Design/methodology/approach
Various input parameters have the significant role in machine performance characteristics. For the optimization of output response, several input parameters have been critically investigated by the various researcher.
Findings
Some advance types of glass; like polycarbonate bulletproof glass, acrylic heat resistant glass and glass-clad polycarbonate bulletproof glass still need some further investigation, because these materials have vast applications in automobile, aerospace and space industries.
Originality/value
Review paper will be beneficial for industrial application and the various young researcher. Paper reveals the detail literature review on Traditional Ultrasonic, Chemical Assisted Ultrasonic, and Rotary Ultrasonic machining of Glass and Glass Composite materials.
... American engineer Lewis Balamuth in 1945 was granted first patent [1,2,6,7,8,10]. USM process have been classified as ultrasonic drilling, ultrasonic cutting, ultrasonic abrasive and ultrasonic dimensional machining [1,4,5,11]. In early 1950's ultrasonic grinding was modified into ultrasonic impact machining [4,8,9,11]. ...
... USM process have been classified as ultrasonic drilling, ultrasonic cutting, ultrasonic abrasive and ultrasonic dimensional machining [1,4,5,11]. In early 1950's ultrasonic grinding was modified into ultrasonic impact machining [4,8,9,11]. It was significant machining process and capable to machine toughest materials [6,7,10,11]. ...
... The ultrasonic drilling (USM) is generally preferred for amorphous, hard and brittle materials [1,8]. Through USM, glass, ceramics, titanium, titanium alloys and many more materials are easily machined [1,2,3,4]. If the hardness of material is more than 40 HRC then USM is successfully performed [3,7,10]. ...
Polycarbonate bullet proof and acrylic heat resistant glasses are used as the functional material in many industrial application. In automobile industries, banks and cabins, polycarbonate bullet proof glass has been used for security purpose. Similarly, acrylic heat resistant glass is used in furnace, microwaves, space craft and airplane applications. In this experimental research paper, Taguchi modal and Grey relational analysis are utilized for the ultrasonic drilling in these materials. For experimentation, input parameters are concentration, abrasive, grit size, power rating, hydrofluoric acid and tool materials. Output parameters are material removal rate, tool wear rate and surface roughness. In which, surface roughness is most significant output parameter, because it describe accuracy of the process. Through optimization analysis, Taguchi modal suggest that 40% abrasive concentration, mixture of (Alumina, Silicon carbide and Boron carbide) abrasive in 1:1:1, 600 grit of abrasive and 1.5% hydrofluoric acid gives best results for drilling in polycarbonate bullet proof glass material. Similarly, in acrylic heat resistant glass, mixture of Silicon carbide and Boron carbide (1:1), 600 grit abrasive and 1% hydrofluoric acid gives the optimum results. Concentration of slurry, abrasive grit size and hydrofluoric acid are the most significant parameters for ultrasonic drilling in both materials. Through Grey relational analysis the surface roughness is improved by 40% and 48% in polycarbonate (UL-752) and acrylic (BS-476) glass respectively.
... Moreover, no any metallurgical variations arise on work surface [2,4]. The history of USM started since 1927 with a research paper reported by A.L. Loomis and R.W. Wood [1,2,3,8]. American engineer Lewis Balamuth in 1945 was granted first patent [1,2,6,7,8]. ...
... The history of USM started since 1927 with a research paper reported by A.L. Loomis and R.W. Wood [1,2,3,8]. American engineer Lewis Balamuth in 1945 was granted first patent [1,2,6,7,8]. USM process have been classified as ultrasonic drilling, ultrasonic cutting, ultrasonic abrasive and ultrasonic dimensional machining [1,4,5]. ...
... In USM process, power supply have an important role. It converts low frequency electrical signals into high frequency electrical signals [2,3,8,9,11,24,26]. After that these signals are transmitted to transducer. ...
Polycarbonate bullet proof glass and acrylic heat resistant glass are used as the functional material in many application. In this research paper, Taguchi modal is utilized for the ultrasonic machining of these material. Surface roughness is significant output parameter, because it define accuracy of the process. Taguchi modal suggest that 40% concentration, mixture of Alumina, Silicon carbide and Boron carbide abrasive in 1:1:1, 600 abrasive grit size and 1.5% HF acid gives best results in polycarbonate bullet proof glass material and for acrylic heat resistant glass, mixture of Silicon carbide and Boron Carbide abrasive in 1:1, 600 abrasive grit size and 1% HF acid gives the best results. More significant parameters contribution in surface roughness are concentration of slurry, grit size of abrasive and HF acid. Optimum parameters improved the surface roughness by 23% and 24% in polycarbonate bullet proof glass and acrylic heat resistant glass respectively.
... Concentration, slurry flow rate and feed rate of tool have minor effects on SR. Lower level of power rating and grit size, gives lower SR [1][2][3]9]. Wear of tool is generally affected by power rating and tool material up to significant extent [4,8]. ...
... In USM, hole accuracy and material removal rate are commonly interrelated with TWR [1,2,4,[7][8][9][10][11]13,14,19,38,[46][47][48][49]. During USM, longitudinal and lateral types of tool wears occur [7,9,12,14,34,38,[50][51][52]. ...
... In USM, hole accuracy and material removal rate are commonly interrelated with TWR [1,2,4,[7][8][9][10][11]13,14,19,38,[46][47][48][49]. During USM, longitudinal and lateral types of tool wears occur [7,9,12,14,34,38,[50][51][52]. Cavitation effect also increase the TWR [20,44,50,52,53]. ...
Polycarbonate bullet proof (UL-752) glass is highly demanded material in automobile, aerospace and space industries. It is also used in security chambers or buildings, because of its unique properties such as; impact bare capacity, hardness, excellent transparency, higher mechanical strength, good dimensional stability etc. Objective of this research investigation is focused at studying the impact of different input parameters (concentration, abrasive, power rating, grit size, HF acid concentration and tool material) on output responses (material removal rate, tool wear rate and surface roughness) in ultrasonic drilling of polycarbonate bullet proof (UL-752) glass. The experiments have been performed by using Taguchi’s L27 orthogonal array and grey relation analysis has been used for the optimization of multiple responses. To find out the significant factors, analysis of variance is further employed. Through GRA approach, MRR and TWR improved by 113% and 100% respectively. HF acid also reduced the delamination affect.
... A reduction in cross-sectional area from the base to the tip increases the gain and an increase in cross-sectional area reduces the gain. Many components profiles exist such as conical, exponential, stepped or combination of these, to magnify or reduce amplitude at the tip of the component [15][16][17]. ...
In this research paper, the Finite Element Analysis is used for the investigation. The modal of polycarbonate bullet proof glass and the abrasive particle is prepared to study the effect of machining mechanism. Through analysis, it concludes that hard abrasive gives the large stressed zone, which increases the material removal rate. In this experimental study, Boron carbide abrasive gives better material removal rate as compared to Silicon carbide and Alumina Abrasive. It also observed from the analysis, higher material removal rate also encourage the tool wear rate. Boron carbide gives higher tool wear rate as compare to other abrasive. The results are verified with the experimentation, it gives the approximately same results of Finite Element Analysis.
... The abrasive slurry is a mixture of irregularlyformed fine abrasive particles, such as boron carbide, Al (Aluminum) oxide, and Si carbide, as well as a liquid mediums [3]. USM techniques do not depend on electrical or chemical characteristics of the workpiece material, which makes it capable of machining a wide variety of materials [13][14][15][16][17]. Thus, this technique is commonly used in machining of hard and brittle materials such as Si [18,19], quartz [20], borosilicate glass [21], titanium alloys [22] and ceramics [23,24], which are difficult to machine using traditional techniques. The basic setup for the USM process is presented in Fig. 2a. ...
Silicon (Si) micromachining techniques have recently witnessed significant advancement, attributable to the high surge in demand for microelectromechanical and microelectronic devices. Micromachining techniques are widely used to cut or pattern Si, in order to obtain high-quality surface finishes for the fabrication of devices. Micromachining techniques are used for the fabrication of three-dimensional (3D) microstructures for microelectromechanical devices. In this work, the capabilities and competencies of non-traditional Si micromachining techniques, including ultrasonic, ion beam milling, laser machining, and electrical discharge machining, are discussed and compared accordingly. The working principles, advantages, limitations, and Si microstructures that have been fabricated before are discussed in detail. Additionally, this work covers the performance reported by multiple researchers on these micromachining methods, spanning the temporal range of 1990 to 2020. The key outcomes of this study are explored and summarized.
... When the waves are intensive enough, cavitating bubbles will generate. Cavitation accompanied with the ultrasonic vibration of sonotrode has been utilized in some manufacturing areas such as ultrasonic cleaning, peening, and machining [10][11][12][13]. Ichida et al. [14] researched the noncontact ultrasonic machining, and the results indicated that the formation of irregular or asymmetrical craters on the target surface is closely related to the cavitation phenomenon. ...
In order to provide some insight into the complex fluid behavior involved in ultrasonic vibration-assisted abrasive waterjet machining, a three-dimensional CFD model is established to investigate the cavitating characteristics. Governing equations of the impacting jet flow field are solved accompanied with the mass transfer equation which is based on Schnerr-Sauer cavitation model. Vibrating motion of the target surface is performed through adopting a moving wall boundary with dynamic mesh method. The evolution of cavitating bubbles and fluid pressure at the impact zone is analyzed. The results imply that the variation of vapor phase fraction has a close correspondence with the pressure fluctuation. Moreover, an increase of vibration amplitude can effectively enhance on the intensity of cavitation. The maximum volume fraction is increased by 78% with a 20 μm increase of amplitude. The experimental results indicate that irregular craters induced by cavitation are formed on the eroded surface when applying ultrasonic vibration to the workpiece.
... Concentration, slurry flow rate and feed rate of tool have minor effects on SR. Lower level of power rating and grit size, gives lower SR ( Jain and Jain, 2001;Jain, 2013;Ghahramani and Wang, 2001). Wear of tool is generally affected by power rating and tool material up to a significant extent (Kumar, 2013;Gilmore, 1991). ...
Purpose
The purpose of this paper, an original research paper, is to study the optimization of material removal rate (MRR) in ultrasonic machining of polycarbonate bulletproof glass and acrylic heat-resistant glass. The machining of these materials is a very tough job. There are so many constraints which need to be taken into account while machining, but without proper knowledge of material properties and machining parameters, machining is not possible. This paper gives basic knowledge about polycarbonate bulletproof and acrylic heat-resistant glass and provides ways as to how these types of materials are processed or machined.
Design/methodology/approach
The Taguchi method was utilized to optimize the ultrasonic machining parameters for drilling these advanced materials. The relationship between MRR and other controllable process parameters such as concentration of slurry, type of abrasive, abrasive grit size, power rating, concentration of HF acid and type of tool material has been analyzed by using the Taguchi approach.
Findings
Through the Taguchi analysis, it is concluded that types of abrasive and HF acid concentrations have a significant role to play in MRR for both materials; in which, type of abrasive have 72.91 and 72.96 percent contribution in MRR for polycarbonate bulletproof and acrylic heat-resistant glass, respectively. Similarly, HF acid concentration has 14.70 and 14.65 percent contribution in MRR for polycarbonate bulletproof and acrylic heat-resistant glass, respectively. The MRR was improved by 34.44 percent in polycarbonate bulletproof glass and 29.25 percent in acrylic heat-resistant glass.
Originality/value
After experimental investigation, the results of the Taguchi modal are validated.
... The cavitation bubble formations facilitate further crack propagation in the material which is most significant for material removal during USM. The same concept is also applicable for USM of ceramics and composites [292,293]. Ultrasonic vibrations enhance the velocity and turbulence of the sharp edged abrasive and render an inelastic deformation which develop the crack on material surface. Further increment in load cause propagation of the cracks. ...
This review paper aims to introduce systematic in-depth analysis of diversified aspects of ultrasonic application in metal joining and processing including its limitations, future prospects and assessments. Allied welding and metal processing technologies employing ultrasonic vibrations either as the primary source to accomplish the intended operation or as an assistant source to improve the operation efficiency and product quality are classified and discussed. The detailed state-of the art, experimentation and progresses of the ultrasonic vibrations and its applications in the above areas are comprehensively examined, evaluated and presented for exhaustive understandings of its physical mechanism. The ultrasonic vibrations assisted processes claim several advantages such as improved mechanical properties, enlarged process window, higher heat generation, better material mixing and enhanced turbulence etc. over the conventional processes which lead to the remarkable and globalized applications of ultrasonic vibrations in the welding and its allied areas in the present century.
... But engineering ceramic materials, represented by Al 2 O 3 ceramics, can be machined by limited processing only due to high hardness and low fracture toughness value. The most widely processing methods are conventional grinding machining and rotary ultrasonic grinding machining (RUGM) (Ghahramani and Wang, 2001;Zhao et al., 2011;Moola et al., 2012). The scope of parts structure processing is not only limited with conventional grinding machining, but also with low processing efficiency and poor reliability (Zhao et al., 2011). ...
Rotary ultrasonic grinding machining (RUGM) can realise higher surface integrity for Al2O3 ceramics. However, the surface morphology characteristics is different from the metal materials due to material removal mechanism. Experimental investigation on RUGM surface morphology of Al2O3 was carried out. The shape self-similarity and statistical self-similarity were proved for RUGM surface morphology of Al2O3 ceramics through the experimental results analysis, so the surface morphology can be investigated with fractal dimension. The change rule and the relationship between fractal dimension surface morphology and the process parameters were also investigated. The experimental results indicate that the fractal dimension of grinding surface morphology is bigger than that of RUGM when the feed rate and grinding height change. Moreover, the fractal dimension is associated with cutting force. The cutting force is small while the fractal dimension is big, then the surface morphology is relatively complex, ups and downs variations of surface morphology are notable.
... There exist several advanced manufacturing methods, i.e., mechanical energy based, thermal based and electrochemical based, that can be used to process hard-to-machine and advanced materials (ceramics, composites, etc.) with superior quality [1,2]. Among these various available machining methods, stationary ultrasonic machining (USM) is quite capable of processing hard and brittle materials irrespective of their electrical and chemical properties, which are generally a limitation for other techniques [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In addition, inclusion of abrasive particles in the form of slurry in stationary USM process is reported to cause some geometrical errors in the process outcomes. ...
Rotary ultrasonic machining (RUM) is a mechanical type non-traditional hybrid machining process which has been utilized potentially to machine a wide range of latest and difficult-to-machine materials, including ductile, hard and brittle, ceramics, composites, etc. In RUM, basic material removal phenomenon of ultrasonic machining and conventional diamond grinding amalgamates together and results into higher material removal rate, improved hole accuracy with superior surface finish. In the current article, several investigations carried out in the domain of RUM for enormous materials have been critically reviewed and reported. It also highlights several experimental and theoretical ensues of RUM to improve the process outcomes and it is reported that process performance can be substantially improved by making the right selection of machine, diamond tooling, material and operating parameters. In recent years, various investigators have explored umpteen ways to enhance the RUM process performance by probing the different factors that influence the quality attributes. Among various accessible modifications in RUM as employed in industries, rotary ultrasonic drilling is more strongly established as compared to other versions such as rotary ultrasonic side milling, face milling, grinding, surface texturing etc. The micro machining applications of RUM have also been discussed briefly. The final section of this paper confers about RUM developments and outlines the aspects for future research.
... B. Ghahramani et al. studied precision ultrasonic machining process focused on the ceramic (Al 2 O 3 ) and investigated the stresses developed in the subsurface of an Al 2 O 3 workpiece hammered by a single abrasive particle due to the force of the vibrating tool. The result of this test determined the stresses responsible for the different fracture modes observed by SEM micrography [25]. ...
Hydroxyapatite bio-ceramics are used for producing implants for bio-medical applications. The generation of hemispherical shaped cavity on hydroxyapatite bio-ceramic is highly demanded for making hip joint. Ultrasonic machining is suitable for the machining of all kind of hard and fragile materials, which are electrically non-conducting. This paper is aimed to design and develop a tool and holding arrangement in ultrasonic machining (USM) for generating hemispherical shaped cavity on hydroxyapatite bio-ceramic which is highly demanded for hip joint replacement. This paper also includes the study of the influences of process parameters such as abrasive grain diameter, abrasive slurry concentration, tool feed rate and power rating on material removal rate, diametrical deviation, and circularity error during ultrasonic machining. From the basic parametric studies, it is observed that the abrasive grain diameter, power rating, and tool feed rate are the most important parameters, which have greater influence on the material removal rate (MRR), diametrical deviation, and circularity error of hemispherical cavity on hydraxyapatite bio-ceramics. It is also concluded that the hemispherical shaped cavity on hydroxyapatite bio-ceramics with dimensional accuracy can be generated by USM with the aid of developed tool geometry and proper control of process parameters during ultrasonic machining.
... Its materialremoval mechanism includes impacting and hammering. The USM is effective and particular for all brittle materials [11], [5]. ...
The necessity of precise and accurate parts without any surface effects in different industries has led to a revolution in machining craft. Given this, non-traditional machining is widely utilized in responding to modern industrial problems. This paper presents a new method in machining of materials using cavitation process. It is called Cavitation Machining (CM). Two kinds of cavitation machining are presented: Hydrodynamic Cavitation Machining (HCM), and Ultrasonic Cavitation Machining (UCM), they will be introduced, and the parameters associated with them will be presented.
... B. Ghahramani et al [8] was taken case study of machining of Al 2 O 3 using USM and discussed in briefly in USM process, mechanism, dynamics and its trends. Deng Jianxin et al [9] have found out in this research MRR is dependent on the effect of the properties & Microstructure of the workpiece materials of alumina-based ceramic composites. ...
The present paper gives a critical review of Alumina and alumina composite ceramic materials machined by different machining process. The article shows that a review on machining of alumina and alumina composites with different input parameters and different output responses such as Material Removal Rate (MRR), Tool Wear Rate (TWR),Surface Roughness(Ra) etc. using a different mechanism of machining technique, SWOT Analysis & its summery results of literature review.
... The research in ultrasonic machining has been initiated in the early seventies by Petrukha [2]. Thereafter many authors have studied the ultrasonic machining in respect of mechanism and mechanics of material removal [3], effect of process parameters on material removal rate [4][5][6][7][8][9]13], tool wear rate [4,10], and surface quality [9,11,12,17] and a comprehensive review by Singh and Khamba [14]. As far as the material removal rate is concerned, Singh and Khamba [8] reported that the power rating has a dominant effect on the MRR as compared to other process parameters during USM of titanium alloys. ...
The paper reports experimental investigation and analysis of material removal rate, tool wear rate, and surface roughness in ultrasonic machining of alumina-zirconia ceramic composite (Al2O3+ZrO2). The experiments were conducted using the full factorial DoE method with an L-8 (2(3)) orthogonal array. The effects of amplitude, slurry concentration and slurry type on the above responses were investigated. Analysis of results indicates that the amplitude has a significant effect on the MRR and surface roughness. An increase in amplitude causes higher MRR and surface roughness. Pure SiC abrasives give better surface finish, whereas the mixed abrasives produce higher tool wear and MRR. The machined surface topography consists of the alterations such as microcavities, plastically deformed layers and fragments of zirconia spread on the surface.
... The micro-USM is used for machining hard and brittle materials. Typical workpiece materials being machined in previous experimental investigations include glass, silicon, and alumina [23,24]. Micro-USM has a set of process parameters similar to macro-USM. ...
Demand for micromachining has been on the rise in recent years owing to increasing miniaturization. Production of parts in microscale, especially with brittle materials, is challenging. Ultrasonic micromachining has been gaining popularity as a new alternative in fabrication of such parts. The process gives a machining option for geometrically challenging and/or brittle material parts that are difficult to machine by conventional processes. In the recent years, possibilities have been explored to improve the “Unit Removal” in microultrasonic machining (micro-USM). However, the research in the area is yet to attain momentum. The present paper is an attempt to present the state of the art in the area of micro-USM based on the literature. Developments in the critical areas of the process like machine tool technology, machining tool head, transducers, and precision attainable in the process with challenges have been discussed. Potential research issues have been explored for future work. Possible application areas have been identified.
... The performance criteria are: precision of the geometry and MRR (Material Removal Rate). Although there exist analytical models describing the fracture modes [2] [3] and the machining process [4] [5], they were mostly developed for dimensions in the millimeter range or above. Their application to the case of drilling of micro holes set out in this paper produced results that weren't in accordance with our experimental data. ...
Brittle materials such as ceramics, glasses and oxide single crystals find increasing applications in advanced micro-engineering products. Machining small features in such materials represents a manufacturing challenge. Ultrasonic drilling constitutes a promising technique for realizing simple micro-holes of high diameter-to-depth ratio. The process involves impacting abrasive particles in suspension in a liquid slurry between tool and work piece. Among the process performance criteria, the drilling time (productivity) is one ofthe most important quantities to evaluate the suitability of theprocess for industrial applications. This paper summarizes recent results pertaining to the ultrasonic micro-drilling process obtained with a semi-industrial 3-axis machine. The work piece is vibrated at 40 kHz frequency with an amplitude of several micrometers. A voice-coil actuator and a control loop based on the drilling force impose the tool feed. In addition, the tool is rotated at a prescribed speed to improve the drilling speed as well as the hole geometry. Typically, a WC wire serves as tool to bore 100 m and 200 m diameter micro-holes of 300 to 1,000 m depth in glass and ruby. The abrasive slurry contains B4C particles of 1 m to 5 m diameter in various concentrations.This paper discusses, on the basis of the experimental results for glass deep hole micro-machining, the influence of the hole diameter (100 or 200 m), and the type of tool (wire or drill). The use of drills help to keep a higher mean drilling speed while the cylindrical wire tools provide a higher speed (twice) in the first 20% ofthe drilling depth. This study shows that the drilling speed in glass deep icro-drilling is depending on depth and type of tool used.
... Although quite acceptable surface quality of grinding can be achieved, the low processing efficiency and high manufacturing cost are insufferable. In the past few years and till now, the ultrasonic grinding attracts extensive attention again as an important technique to grind advanced ceramics [6,7] . Ultrasonic grinding is a hybrid machining process that combines the diamond grinding and the ultrasonic machining, which can improve the grinding efficiency and quality, so as to meet the special case of machining brittle materials including ceramics. ...
In order to grind the ceramic blade surface with the Numerical Control contour evolution ultrasonic grinding method using the simple shape grinding wheel, primary comparative experiments of creep feed grinding with and without ultrasonic vibration were carried out to grind Al2O3 ceramics so as to implore the effects of different process parameters on the machined surface quality. It can be concluded that when the direction of ultrasonic vibration is parallel to the direction of creep feed, the value of the surface roughness will be decreased; otherwise the surface quality will become worse. With the ultrasonic grinding method, the slower feed-rate, the smaller grinding depth, the higher grinding speed and the compound feed grinding method should be applied in order to improve the surface quality. The creep feed grinding mechanisms with and without ultrasonic vibration were analyzed theoretically from the experimental results. With the selected grinding parameters resulted from the experiments, the feasibility experiment of ultrasonic grinding ceramic blade surface was carried out.
... All materials tending to a brittle fracture behavior can be machined by micro USM. Examples include high-performance ceramics, glass, graphite and a part of the fiber-reinforced plastics [17,18]. Geometrical capabilities of micro USM have been testified by drilling, slot machining and 3D machining. ...
Micro USM and micro EDM are emerging processes capable of micromachining nonconductive and conductive materials respectively. This paper presents some process improvements achieved in micro USM and micro EDM. Research issues involved in the process improvement are discussed and the extended capabilities of the above said processes are presented. It is noticed that in micro USM, in addition to size ratio and hardness ratio, the slurry medium also plays a role in determining the two body and/or three body mechanism of material removal. Process improvements in micro EDM are possible with the introduction of strategies such as planetary tool motion (non circular blind micro hole machining), uniform tool wear method (3-D micromachining), uniform tool shape method (freeform micromachining), and vibration assisted micro EDM (for high aspect ratio micromachining).
... Three well-recognized major removal mechanisms are described by the researchers as follows [1][2][3][4][5]: (i) the hammering action by the larger grits when the tool, abrasive and work are in contact; (ii) the impact action by the smaller free-moving grits in the gap formed by the larger grits (called 'working gap'); and (iii) the cavitation-erosion action as the bubble collapses in the working gap by absorbing ultrasonic vibration energy. Since the major and vital material removal mechanism is the hammering action or direct indentation by the larger abrasives, many researchers [4,[6][7][8][9][10][11][12] conducted fundamental research on the mechanical indentation technique by impacting small micro-level either sharp or round indenters on the surface of hard-brittle materials, as to simulate the real USM removal mechanisms. In detail study by applying a round micro-indenter on several hard-brittle materials like silicon nitride, glass, sapphire and ZnS. ...
Micro-chipping via micro-cracks, due to rapid mechanical indentations by abrasive grits, is the fundamental mechanism of material removal during ultrasonic machining (USM) of hard-brittle materials like ceramics and glass. This study aims mainly to investigate the adverse effects of this inherent removal phenomena on the hole integrity such as entrance chipping, wall roughness and subsurface damage. It also presents the material removal mechanism happens in the gap between the tool periphery and the hole wall (called 'lateral gap'). To do so, experiments were conducted for drilling holes on three advanced structural ceramics, namely, silicon carbide, zirconia, and alumina. Earlier published basic studies on the initiation of different crack modes and their growth characteristics are employed to explain the experimental findings in this USM study. It is realized that the radial and the lateral cracks formed due to adjacent abrasives, which are under the tool face, extends towards radial direction of the hole resulting in entrance chipping. Additionally, the angle penetration and the rolling actions of the abrasives, which are at the periphery of the tool, contribute to the entrance chipping. Later on, in the 'lateral gap', the sliding (or abrasion) and the rolling mechanisms by the larger abrasives take part to material removal. However, they unfavorably produce micro-cracks in the radial direction resulting in surface and subsurface damages, which are ultimately responsible for higher wall-surface roughness. Since the size of micro-cracks in brittle materials is grit size dependent according to the earlier studied physics, it is realized that such nature of the hole integrity during USM can only be minimized by employing smaller grit size, but cannot fully be eliminated.
The objective of the present study is to review of the ultrasonic machining process. Generally ultrasonic machining is based on the different-different parameters which are used to increase the output result like material removal rate, tool wear rate, surface roughness, micro hardness etc. Different parameters produce different output result. The present study gives an idea about which parameters put an effect on output parameters. It also gives an idea about which work material is suitable for machining with different parameters. Ultrasonic machining (USM) is a mechanical material removal process used to erode holes and cavities in hard or brittle work pieces by using shaped tools, high-frequency mechanical motion, and an abrasive slurry. Unlike other non-traditional processes such as laser beam, and electrical discharge machining, ultrasonic machining does not thermally damage the work piece or appear to introduce significant levels of residual stress, which is important for the survival of materials in service. The fundamental principles of stationary ultrasonic machining, the material removal mechanisms involved and the effect of operating parameters on material removal rate, tool wear rate, and work piece surface finish of titanium and its alloys are reviewed, for application in manufacturing industry.
Ultrasonic machining (USM) is an unconventional machining process. It is mainly used for material removal from the brittle and hard workpiece by using a high-frequency longitudinal mode of vibration. There are several process parameters are used in the ultrasonic machining to achieve the outcomes like tool wear rate, surface roughness, material removal rate, hole quality, and conicity. Tool wear is the most unwanted occurrence of the machining process as it unpleasantly affects the tool life, surface finish of the machined surface, and its dimensional precision. The destructive and non-destructive methods can be used for quality assessment and defect identification during machining. However, these methods suffer from limitations as their high setup and operating cost. Alternatively, condition monitoring can be used to monitor the machining quality and defect identification in the ultrasonic machining process.
The different unconventional machining processes are used in modern development of material and manufacturing industries. Ultrasonic Machining (USM) is changing the manufacturing industries with its exceptional performance. Ultrasonic machining is an abrasive process which can be used for machining any material with the help of its vibrating tool and abrasive slurry. In this paper describes the material removal mechanism, machining factors, machining with different materials and its process optimization of USM through collection of different literature reviews. The advancement of the USM process and its future scope has also been presented.
Rotary ultrasonic machining (RUM) is an abrasive based advanced machining technique for cutting and finishing of various hard and fragile materials like ceramic, ceramics composite, glass, titanium and its alloy etc. RUM is the development over stationary ultrasonic machining for enhancement of MRR, geometrical accuracy and surface roughness. The basic mechanism of RUM is the combination of ultrasonic machining and conventional diamond grinding. In this chapter development, principle, mechanism, setup details of rotary ultrasonic machining has been discussed. It also highlights the effects of diverse input parameters on performance of RUM. The MRR always increases with spindle speed; tool feed rate and ultrasonic power. The surface roughness improved with spindle speed but worse with tool feed rate and ultrasonic power. The chipping size reduced with spindle speed but increase with tool feed rate and ultrasonic power. The cutting force reduces with spindle speed and ultrasonic power but increases with tool feed. Various advancements in RUM has also discussed. A new technique for drilling called robotic rotary ultrasonic drilling (RRUD) was developed. The application area of rotary ultrasonic machining (RUM) in micro domain has also been highlighted. It is extensively useful for generation of micro feature like micro hole, micro channel, complex micro cavity etc. on various materials such as quartz, glass, SiC, and Al2O3.
One of the effective nonconventional machining processes is ultrasonic machining (USM) that can machine brittle as well as hard material. An ultrasonic-induced vibrating tool pressurizes the abrasive grains towards the target material and therefore removes the material. Machining precision is one of the major factors that is very critical in achieving parts with high-dimensional tolerances. Production of micro-holes is one of the major applications of micro-USM process. However, chippings produced at the edge of the hole adversely impacts the machining precision. Chippings can be taken care off by employing electrorheological fluid in tandem with the micro-USM process and therefore giving birth to a hybrid micromachining process, i.e., electrorheological fluid-assisted micro-USM. This chapter briefs the audience with principles of electrorheological fluid-assisted micro-USM process.
The present work is focused on the creation of blind holes on float glass using CNC conventional drilling (CD) by deploying multi-shape of tools. The selected tools are listed as a hollow abrasive tool, pinpointed conical tool, flat cylindrical tools, and concave circular tool. The experimental trials are performed by considering industrial conditions. The weight of the tools is estimated in two cases, i.e., fresh tool and after CD process to analyze the overall tool wear. Apparently, micrographs are aided to investigate the phenomena of lateral and end face tool wear while creating blind holes at two stages: (a) fresh tool and (b) after CD. Concave circular tool possessed a minimum percentage of weight loss, i.e., 4.92% after CD and is revealed as a most effective tool, which could be used for drilling purpose followed by the hollow abrasive tool.
Float glass, which is a hard and brittle material, is generally machined and drilled using rotary ultrasonic machining and conventional drilling to create products such as solar panels, metrological instruments, etc. But researchers are facing serious issues with regard to tool wear and opting for best shape of tool for the drilling purpose. In this study, blind holes are made on float glass specimen using rotary ultrasonic drilling and CNC conventional drilling process with the aid of multi-shaped tools. The opted tools are namely hollow abrasive tool, pin-pointed conical tool, flat cylindrical tools, and concave circular tool. The entire experimental work is accomplished by considering industrial conditions. Multi-shaped tool’s weight is computed at three stages i.e. (a) fresh tool, (b) after rotary ultrasonic drilling, and (c) after conventional drilling to analyze the overall tool wear. Apparently, micro-studies are used to investigate the phenomena of lateral and end face tool wear while creating blind holes at these three stages. It is revealed that the concave circular tool achieved a minimum percentage of weight loss i.e. 4.92% after conventional drilling and 1.96% after rotary ultrasonic drilling process, which could be preferred for drilling purpose followed by the hollow abrasive tool.
Lapping is a key processing step for precision parts, which directly affects machining quality, precision, and efficiency. Due to some drawbacks of free-abrasive lapping such as deep scratches on the lapped surface, lower lapping efficiency for lower lapping speed, severe waste of abrasive, high-processing cost, and so on, conventional fixed-abrasive lapping (CFL) technology was proposed and developed recently. Meanwhile, considering the unique advantages of the ultrasonic-assisted machining during the processing of those hard and brittle materials and the effect of ultrasonic vibration on the selfsharpening characteristic of abrasive pellet, a novel ultrasonic-assisted fixed-abrasive lapping (UAFL) technology is put forward and corresponding lapping device for engineering ceramics cylindrical part is developed in this paper. Meanwhile, UAFL mechanism and characteristics were studied theoretically and experimentally. Research results show that superimposed ultrasonic vibration changes the lapping movement characteristics and material removal mechanism to a certain extent, helping to heighten material removal rate, smoothen the waveform of tangential force, reduce the average tangential force, and improve surface machining quality. UAFL can be regarded as a high efficiency and precision processing technology for engineering ceramics cylindrical part.
There are a lot of developments in the micro manufacturing methods for the production of the three-dimensional miniaturized products made up of different advanced materials. Ultrasonic micro machining is an essential technique for the fabrication of micro parts on the hard, brittle and non-conductive materials like glass, ceramics and silicon with high aspect ratio. Ultrasonic micro machining is the mechanical type non conventional micro machining process. Material removal mechanism of USMM is similar to macro ultrasonic machining process. Adequate surface finish with stiff tolerances and dimensions can be achieved by ultrasonic micro machining (USMM) on hard and brittle materials. During the last decades, a number of researchers have explored experimentally and theoretically this ultrasonic micro machining (USMM) process technique with different materials. Recent development on ultrasonic micro machining (USMM) process has been highlighted and discussed in details with different types of ultrasonic micro machining (USMM) set up and material removal mechanism. Design and developments of micro-tools for USMM process have also been discussed. Influences of different process parameters on various responses of USMM have been discussed here.
This paper presents an alternative splitting method of both thick glass (transparent material) and Sic ceramic (non-transparent) sheets without causing removal of material based on controlled fracture technique with elliptic microwave spot. This method is called as MISM (Microwave Induced Split Method) for short. First, the fact of that 2.45 GHz microwave could volumetrically heat 10-mm thickness NaCa glass and Sic ceramic sheets is theoretically proved. Then MISM physical model and corresponding apparatus is developed. Simulating of distribution of power loss density of microwave spot in the physical model is performed. Simulating results shows that an elliptic volumetrically heating microwave spot is obtained, which is testified by measured temperature distribution on the input and output surface of sheet. NaCa glass sheets with max thickness of 4 mm and Sic sheets with max thickness of 3 mm are both split without causing removal of material. The split line is straight. The split procedure is as same as the procedure of controlled fracture technique with laser spot. The sub-processes of split were related with the movement of three parts of elliptic microwave spot.
Thanks to the favourable combination of outstanding mechanical, thermal and chemical properties, engineering ceramics find widespread applications in the modern industry. Nevertheless, their extensive use is still hindered by the implementation of a labour and cost intensive manufacturing chain. Electro, chemical and physical shaping techniques, like electrical discharge machining, additive manufacturing and laser beam machining, have recently been investigated to offer efficient alternatives. This work provides a comprehensive overview of the current technological trends and main perspectives on electro, chemical and physical shaping of engineering ceramics with a focus on experimental works. The literature data trace back to the 80s.
Residual stress of engineering ceramics is one of surface integrity evaluation indexes affecting the parts’ strength properties. Rotary ultrasonic grinding machining is the most powerful machining method for engineering ceramics with better surface integrity. The residual stress field distribution is changed due to micro cracks which are inevitable in the process. A residual stress distribution model of machined surface micro crack tip has been established in the paper. And the experimental results enable us to obtain surface residual stress distribution of engineering ceramics in rotary ultrasonic grinding machining. Then, we propose an evaluation parameter called confidence stress tolerance to evaluate surface residual stress characteristic. Preliminary results indicate that surface residual stress distribution is in line with the normal distribution. Confidence stress tolerance is an effective parameter to improve the evaluation reliability. Furthermore, precision and affecting factors of confidence stress tolerance evaluation have also been investigated.
The latest research achievements and the development of machining technologies for structural ceramics materials in home and abroad were summarized, such as laser, electrical discharge machining (EDM), plasma arc, ultrasonic wave, microwave and other special machining techniques, composite machining technologies, as well as interface thermal chemistry reaction machining, high-speed (super speed) grinding and electrolytic in process dressing (ELID) grinding technologies on the basis of traditional grinding technology, to provide help for developing good quality, high efficiency and low cost machining technologies in structural ceramics materials at home.
The present paper gives a critical review of Alumina and alumina composite ceramic materials machined by different machining process. The article shows that a review on machining of alumina and alumina composites with different input parameters and different output responses such as Material Removal Rate(MRR),Tool Wear Rate(TWR),Surface Roughness(Ra) etc. using a different mechanism of machining technique & its SWOT Analysis
Precision grinding of silicon carbide ceramic micro-structured moulds is becoming more common in the area of the moulding of glass materials. However, in micro-structured grinding of super-hard and brittle materials, problems frequently occur in terms of chipping and rounding of micro-structural edge features. In order to overcome these technological constraints, a promising method using ultrasonic vibration of workpiece materials is proposed. The design of a novel ultrasonic vibration apparatus and the experimental investigation of ultrasonic vibration assisted grinding of SiC micro-structures are presented. The experimental results show that the application of ultrasonic vibration can enhance the ground surface quality and improve the edge features of micro-structures.
The impact of cutter against the materials can be regarded as the rigid ball with certain energy oblique impact against the semi infinite space in the ultrasonic vibration cutting process. The cutter and materials three-dimensional surface stress state was theoretically deduced from building the dynamic shock model in Hertz contact state. Ultrasonic vibration cutting in the tiny cutting depth can be regarded as the contact extrusion process of blunt pressure head oblique impact on materials, the material indentation and crack development trend was given based on the surface stress analysis and test results of rigid ball oblique impact on the glass. The indentation and crack development of spherical pressure head oblique impact on the brittle materials was analyzed, material failure in the back edge with deeper crack is controlled by tensile stress, the tensile stress values depend on the friction coefficient and the normal pressure, material failure crack caused by shear stress on both sides exist on the material surface. Ultrasonic vibration can reduce normal pressure and crack to come into being. Cutting fluid lubricating can reduce the friction coefficient to control with only shallow crack produced in the cutting process.
Ultrasonic machining is used for machining hard and brittle materials: semiconductors, glass, quartz, ceramics, silicon, germanium, ferrites etc. Titanium and its alloys are alternative for many engineering applications due to their superior properties such as chemical inertness, high tenacity, high specific strength, excellent corrosion resistance and oxidation resistance. In the present investigation, the effect of energy input rate on the surface topography has been evaluated, under controlled experimental conditions. It has been found that the mode of material removal may change from brittle fracture to ductile failure under extremely small energy input conditions. Moreover, a mixed mode with varied proportion of brittle fracture and plastic deformation could be obtained through systematic variation of the input parameters. In comparison to an electrical energy based method such as WEDM, the titanium components processed by USM does not exhibit any appreciable surface damage in the form of recast material, heat affected zone or residual stresses.
In ultrasonic machining (USM), hard and brittle material is removed by the hammering of abrasive particles excited by ultrasonic vibration delivered to the tool. USM does not significantly alter metallurgical, chemical, or physical properties of work material because of its non-thermal, non-chemical and non-electrical nature. USM has been downscaled to generate micro-scale features in brittle and hard materials such as silicon, quartz, glass and ceramics. Micro holes, slots and 3-D features have been machined. However, the knowledge base for micro USM is far from sufficient to provide instructive rules in applying micro USM to practical manufacturing. This paper presents a systematic literature review and reports the state-of-the-art investigation in micro USM based on previous experimental and theoretical results. Research issues are identified for further improvement of this special micromachining process.
Ultrasonic machining (USM) is a mechanical material removal process used to erode holes and cavities in hard or brittle workpieces by using shaped tools, high-frequency mechanical motion, and an abrasive slurry. The fundamental principles of stationary ultrasonic machining, the material removal mechanisms involved, proposed models for estimation of machining rate, the effect of operating parameters on material removal rate, tool wear rate, and workpiece surface finish, research work reported on rotary mode USM, hybrid USM, process capabilities of USM have been extensively reviewed in this article. The limitations of USM, gaps observed from the literature review, and the directions for future research have also been presented. Overall, this article presents a comprehensive review of USM process for advancement of the process through fundamental insights into the process.
In this paper, the characteristic of grinding force in two-dimensional ultrasonic vibration assisted grinding nano-ceramic was studied by experiment based on indentation fracture mechanics, and mathematical model of grinding force was established. The study shows that grinding force mainly result from the impact of the grains on the workpiece in ultrasonic grinding, and the pulse power is much larger than normal grinding force. The ultrasonic vibration frequency is so high and the contact time of grains with the workpiece is so short that the pulse force will be balanced by reaction force from workpiece. In grinding workpiece was loaded by the periodical stress field, which accelerates the fatigue fracture.
In this paper, the technique of ultrasonic flexural vibration assisted chemical mechanical polishing (UFV-CMP) was used for sapphire substrate CMP. The functions of the polishing pad, the silica abrasive particles, and the chemical additives of the slurry such as pH value regulator and dispersant during the sapphire's UFV-CMP were investigated. The results showed that the actions of the ultrasonic and silica abrasive particles were the main factors in the sapphire material removal rate (MMR) and the chemical additives were helpful to decrease the roughness of sapphire. Then the effects of the flexural vibration on the interaction between the silica abrasive particles, pad and sapphire substrate from the kinematics and dynamics were investigated to explain why the MRR of UFV-CMP was bigger than that of the traditional CMP. It indicated that such functions improved the sapphire's MRR: the increasing of the contact silica particles’ motion path lengths on the sapphire's surface, the enhancement of the contact force between the contact silica particles and the sapphire's surface, and the impaction of the suspending silica particles to the sapphire's surface.
Precision machining where high quality and enhanced functionality are needed has shown a rapid growth in the fields such as the electronics manufacturing, including communication devices and semiconductors, and the aircraft industry. There is a strong demand for precision machining of non-conducting materials. The ultrasonic machining method makes it possible to achieve high quality, high accuracy, and good surface finish. The technology has been brought into the machining of non-conducting brittle materials such as ceramics, crystals, and graphite. A number of machining variables are determined by the testing conditions, such as the size of abrasives, the resonance frequency, the amplitude of the end point of the tool, and the rotation of the tool. This research examines the effect of ultrasonic vibration on machining conditions for non-conducting brittle materials, using a tungsten-carbide tool for the machining to improve the processing accuracy.
The sapphire substrates are polished by traditional chemical mechanical polishing (CMP) and ultrasonic flexural vibration (UFV) assisted CMP (UFV–CMP) respectively with different pressures. UFV–CMP combines the functions of traditional CMP and ultrasonic machining (USM) and has special characteristics, which is that ultrasonic vibrations of the rotating polishing head are in both horizontal and vertical directions. The material removal rates (MRRs) and the polished surface morphology of CMP and UFV–CMP are compared. The MRR of UFV–CMP is two times larger than that of traditional CMP. The surface roughness (root mean square, RMS) of the polished sapphire substrate of UFV–CMP is 0.83Å measured by the atomic force microscopy (AFM), which is much better than 2.12Å obtained using the traditional CMP. And the surface flatness of UFV–CMP is 0.12μm, which is also better than 0.23μm of the traditional CMP. The results show that UFV–CMP is able to improve the MRR and finished surface quality of the sapphire substrates greatly. The material removal and surface polishing mechanisms of sapphire in UFV–CMP are discussed too.
Brittle materials such as ceramics, glasses and oxide single crystals find increasing applications in advanced micro‐engineering products. Machining small features in such materials represents a manufacturing challenge. Ultrasonic drilling constitutes a promising technique for realizing simple micro‐holes of high diameter‐to‐depth ratio. The process involves impacting abrasive particles in suspension in a liquid slurry between tool and work piece. Among the process performance criteria, the drilling time (productivity) is one of the most important quantities to evaluate the suitability of the process for industrial applications.
Alumina being a lowest-cost high-performance ceramic is considered when seeking an alternate material for increased wear resistance, improved chemical resistance, dimensional stability, decreased friction and higher temperature use. Ultrasonic machining is a valuable process for the precision machining of such materials. In the present work, the mechanism of material removal by Silicon Carbide abrasives in alumina based ceramics with no sub-surface defects using USD process has been simulated. The Finite element method (FEM) software, ANSYS 5.4 is used for stress analysis under assumptions. The boundary conditions are applied. The theory of Zhang et al. (1999) for the number of abrasives under the tool is assumed to fit in the present model. The stress analysis confirms that the mechanism involved in material removal of brittle materials is initiation and propagation of the median vent cracks and lateral cracks. Fracture at the exit of hole was observed during experimentation. The material removal rate initially increases and then decreases with the increase of power input. The variation of MRR with respect to feed rate is very high, when compared to the variation due to power rating and slurry concentration. It is concluded that the Finite element model developed for the interaction of the abrasive and work piece is predicting the stress pattern with reasonable accuracy. The results of FEM analysis are validated by conducting experiments as per Taguchi's L9 OA.
The need for micro-features, components and products is rapidly increasing in diverse industries such as electronics, medical and aviation. Product miniaturization demands innovative manufacturing methods. Various existing macro-manufacturing processes are being modified to perform micro-scale manufacturing. Electro-physical and chemical micromachining processes play important role in this field due to their special material removal mechanisms. This paper reports the worldwide technical developments and state-of-the-art of electro-physical and chemical micromachining processes. Issues related to the supporting technologies such as standardization, metrology and equipment design are briefly assessed. Non-technological issues including environmental effects and education are also discussed.
In Ultrasonic Machining several theories have been put forward by various researchers. Inspite of such efforts, there is still a need for developing a comprehensive theoretical model which will describe the material removal process. In the present work the authors have undertaken the task of developing a comprehensive analytical model for the estimation of material removal rate and performing extensive experimental investigation in order to make an in-depth study of the mechanism of material removal process by considering the major influencing parameters. The power involved in such machining has also been estimated. Fall in MRR at higher static loads has been successfully explained by the theoretical postulation which is in good agreement with the experimental findings.
This paper presents a dynamic analysis of the ultrasonic machining process based on impact mechanics. Equations representing the dynamic contact force and stresses caused by the impinging of abrasive grits on the work, are obtained by solving the three-dimensional equations of motion. The factors affecting the material removal rate have been studies. It is found that the theoretical estimates obtained from the dynamic model are in good agreement with the experimental results.
Ultrasonic machining is used for machining hard and brittle materials. The mechanism of removal is complex but it is generally accepted that for non-porous materials the mostimportant constituent processes are the direct hammering of abrasives by the tool and high velocity impact of free moving abrasive particles on the work surface. This paper deals with a simple but effective approach using a profile relocation technique to study the relative role of the two processes. A mild steel tool was used with boron carbide abrasive to machine high speed steel, tungsten carbide and plate glass workpieces the design of which enables the two processes to be separated. Removal is found to be primarily by hammering.
A theoretical investigation into the mechanics of ultrasonic machining is presented in this paper on the following lines: the material removal in ultrasonic machining is due to the periodic hammering by the cutting tool on the workpiece material through rigid spherical abrasive particles. The dislodging of material from the workpiece during machining is due to brittle fracture. No consideration is given to the cavitation erosion and the removal of the material due to the impinging of the flying abrasive particles which are being projected onto the workpiece material by the vibrating tool. Simulating by the principle of elastic waves propagation, the strain energy density distribution in a brittle half space, when a single rigid abrasive grit gives a single ‘half-wave displacement with a cutoff’ to it, is ascertained. The fracture profile due to this is found and the material removal rate is calculated. Maintaining the same amplitude of vibration, the static loads at the abrasive workpiece contacts are calculated, for different sizes of abrasive grits, independently. Finally, the variation of machining rates for constant static loads with the mean diameter of abrasive grains is determined, for the given amplitude and frequency of vibration. The results agree with the experimental observations available in the published literature (Nishimura et al. 1959)
Results of sliding wear tests on three alumina ceramics with different grain sizes are discussed in the light of crackresistance (R-curve, or T-curve) characteristics. The degree of wear increases abruptly after a critical sliding period, reflecting a transition from deformation-controlled to fracture-controlled sulface removal. This transition occurs at earlier sliding times for the aluminas with the coarser-grained microstructures, indicative of an inherent size effect in the wear process. A simplistic fracture mechanics model, incorporating the role of internal thermal expansion mismatch stresses in the crack-resistance characteristic, is developed. The results suggest an inverse relation between wear resistance and large-crack toughness for ceramics with pronounced Rcurve behavior.
An analysis of material removal in ultrasonic machining considering direct impact of abrasive grains on the workpiece is presented. Non-uniformity of abrasive grains is considered by using a probability distribution for the diameter of the abrasive particles as suggested by Rozenberg. The analysis is applied to calculate material removal rate for the case of glass using 400 mesh Norbide abrasive and mild steel tool for various values of static force and amplitude of tool oscillation.
A bonded-interface sectioning technique is used to examine subsurface damage modes and to identify mechanisms of material removal in repeated single-point scratching of alumina as a function of grain size, load, and number of passes. In the fine grain alumina, the lateral and median crack system is observed, together with intergranular microcracks and intragrain twin/slip bands distributed within the plastic zone. The distributed form of damage, namely twin/slip bands and intergranular microcracks, are also observed in the coarse grain alumina; but no evidence is found for well-defined median and lateral cracks in this material. The mechanism of material removal in alumina is identified as grain dislodgement resulting from grain boundary microcracking, irrespective of the grain size. Extension of lateral cracks is found to contribute to the material removal process only in the fine grain alumina scratched under a large load and after several passes. A model for the microfracture-controlled material removal process is proposed that relates the volume of material removed to the applied load and material properties including grain size, elastic modulus, hardness, and short-crack toughness. Removal rate is shown to be proportional to grain sizeI
1/2 and to loadP
2. The model and the experimental results obtained in scratching are used to describe the action of an individual abrasive grit in grinding and other abrasive machining processes.
An experimental and theoretical investigation of the impact response of case hardened bearing materials
- J Sommer
J. Sommer, An experimental and theoretical investigation of the impact response of case hardened bearing materials. MS thesis, University of Nebraska–Lincoln, 1991.
Indentation fracture of single crystal and polycrystalline aluminium oxide
- S S Smith
- B J Pletka
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Ultrasonic Machining of Ceramics, Society of Manufacturing Engineers
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Effect of Microstructure on Rate of Machining of Ceramics. Presented at the fall meeting of the Basic Science and Nuclear Divisions
- W R Rice
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