Experimental investigations on core drilling by ultrasonic-vibration-assisted grinding for hard-to-machine materials - A review

Citation: Qin, N., Lei, J., & Pei, Z. J. (2016). Experimental investigations on core drilling by ultrasonic-vibration-assisted grinding for hard-to-machine materials - A review. International Journal of Manufacturing Research, 11(1), 28-52. doi:10.1504/IJMR.2016.076976Ultrasonic-vibration-assisted grinding (UVAG), a hybrid machining process combining material removal mechanisms of diamond grinding and ultrasonic machining, has been used to machine various hard-to-machine materials. Large amount of research work on UVAG has been carried out since it is invented. However there are few review papers to cover the current literature on UVAG. The emphasis of this literature review is the experimental investigations of the drilling process with ultrasonic vibration using a core drill with metal-bonded diamond abrasives. Experimental results are summarised and compared. The inconsistent results and their reasons are discussed. Furthermore, directions of future research on UVAG are also presented. © 2016 Inderscience Enterprises Ltd

Hybrid micro-machining processes : a review

Micro-machining has attracted great attention as micro-components/products such as micro-displays, micro-sensors, micro-batteries, etc. are becoming established in all major areas of our daily life and can already been found across the broad spectrum of application areas especially in sectors such as automotive, aerospace, photonics, renewable energy and medical instruments. These micro-components/products are usually made of multi-materials (may include hard-to-machine materials) and possess complex shaped micro-structures but demand sub-micron machining accuracy. A number of micro-machining processes is therefore, needed to deliver such components/products. The paper reviews recent development of hybrid micro-machining processes which involve integration of various micro-machining processes with the purpose of improving machinability, geometrical accuracy, tool life, surface integrity, machining rate and reducing the process forces. Hybrid micro-machining processes are classified in two major categories namely, assisted and combined hybrid micro-machining techniques. The machining capability, advantages and disadvantages of the state-of-the-art hybrid micro-machining processes are characterized and assessed. Some case studies on integration of hybrid micro-machining with other micro-machining and assisted techniques are also introduced. Possible future efforts and developments in the field of hybrid micro-machining processes are also discussed

Rotary ultrasonic machining of difficult-to-machine materials: experimental and theoretical investigations

Doctor of PhilosophyDepartment of Industrial & Manufacturing Systems EngineeringZhijian PeiMeng (Peter) ZhangHigh-performance materials such as composite materials, metal alloys, and advanced ceramics are attractive to engineering applications in aerospace, automobile and sport industries. Materials with superior properties are often difficult-to-machine due to their high strength, high hardness, and high toughness, which make the cutting force and temperature at the cutting interface very high and result to a short tool life. This limits their market expansion due to the high cost of machining with current machining procedures. However, the demand for high-performance materials is increasing in certain industries such as aerospace and automotive. In addition to machining of high performance materials, some of the conventional materials such as rocks also can be categorized into difficult-to-machine materials. Some causes which made rock drilling complicated are expose to several rock types in a single drilling, an infinite variability of rock properties, relatively high hardness and high abrasiveness of rocks, friction between rock and tool, severe wear and damage to tools etc. Therefore, it is crucial to develop more cost-effective machining processes for difficult-to-machine materials. Rotary ultrasonic machining (RUM), a hybrid non-traditional machining process combining the material removal mechanisms of abrasive grinding and ultrasonic machining, has the potential for low-cost and high quality machining of difficult-to-machine materials. Researchers have shown that RUM can attain a higher material removal rate than both ultrasonic machining (USM) and grinding. RUM can also drill deep holes with high accuracy, improved surface finish, and low cutting force and torque. The objectives of this research are to investigate the relationships between input variables and output variables of RUM of difficult-to-machine materials, to study the measurement methods of ultrasonic vibration amplitude and the effects of tool natural frequency on ultrasonic vibration amplitude, and to model RUM of rocks. In this dissertation, research has been conducted by experimental, numerical, and theoretical investigations on output variables including cutting force, torque, surface roughness, edge chipping, and delamination. The goal of this research is to provide new knowledge based on machining difficult-to-machine materials on RUM in order to improve the quality of the machined holes while decreasing the machining cost and to study the effects of machining variables (feedrate, tool rotation speed, and ultrasonic power) and tool variables (abrasive size and concentration, tool diameter, and tool geometry) on output variables. This dissertation firstly provides the introduction to difficult-to-machine materials and rotary ultrasonic machining. After that Chapter 2 investigates the effects of input variables on cutting force, torque, and surface roughness, and study the effects of machining variables, tool end angle, and the use of a backing plate on the delamination of RUM of CFRP. Chapter 3 studies the comparison between intermittent RUM and continuous RUM when machining K9 glass from the perspectives of cutting force, surface roughness, and chipping size. Chapter 4 investigates the effects of input variables on cutting force, torque, surface roughness, and edge chipping of the RUM of basalt, travertine, and marble, and development of a mechanistic predictive cutting force model for RUM of rocks based on the ductile mode removal and brittle fracture mode removal of rock under the indentation of a single abrasive particle. Chapter 5 discusses the effects of tool natural frequency on ultrasonic vibration amplitude. Finally, conclusions and contributions on RUM drilling are discussed in Chapter 6

Current Concepts for Cutting Metal-Based and Polymer-Based Composite Materials

Due to the variety of properties of the composites produced, determining the choice of the appropriate cutting technique is demanding. Therefore, it is necessary to know the problems associated with cutting operations, i.e., mechanical cutting (blanking), plasma cutting plasma, water jet cutting, abrasive water jet cutting, laser cutting and electrical discharge machining (EDM). The criterion for choosing the right cutting technique for a specific application depends not only on the expected cutting speed and material thickness, but it is also related to the physico-mechanical properties of the material being processed. In other words, the large variety of composite properties necessitates an individual approach determining the possibility of cutting a composite material with a specific method. This paper presents the achievements gained over the last ten years in the field of non-conventional cutting of metal-based and polymer-based composite materials. The greatest attention is paid to the methods of electrical discharge machining and ultrasonic cutting. The methods of high-energy cutting and water jet cutting are also considered and discussed. Although it is well-known that plasma cutting is not widely used in cutting composites, the authors also took into account this type of cutting treatment. The volume of each chapter depends on the dissemination of a given metal-based and polymer-based composite material cutting technique. For each cutting technique, the paper presents the phenomena that have a direct impact on the quality of the resulting surface and on the formation of the most important defects encountered. Finally, the identified current knowledge gaps are discussed.publishedVersio

Three-Dimensional Finite Element Analysis of Conventional and Ultrasonic Vibration Assisted Micro-Drilling on PCB

Recent advancement in society’s demands has forced industries to produce more and more precise micro parts. With an advancement in engineering sciences, current manufacturers in various fields such as aerospace, medical, electronics, automobile, biotechnology, etc. have achieved the potential to fabricate miniaturized products, but with numerous technical challenges. Dimensional accuracy and surface integrity of the machined components are the key challenges and at the same time, cost minimization is strongly desired. To meet these challenges and demands, improvements in machining regarding new procedures, tooling, tool materials and modern machine tools are highly essential. Micromachining has shown potential to achieve the fast-growing needs of the present micro manufacturing sector. Additionally, new machining techniques like ultrasonic machining, laser drilling, etc. have been developed as an alternative source to reduce obstructions caused during macro/micro machining. The present research aims to perform three-dimensional (3D) finite element dynamic analysis for micro-drilling of multi-layer printed circuit boards (PCBs). Both conventional and ultrasonic vibration assisted micro-drilling (UVAMD) FE simulations have been compared to predict and evaluate the effect of process parameters on the output responses like stress generation and reaction forces and burr formation on the workpiece surfaces. The Lagrangian based approach is followed for the FE simulation including the mass and inertial properties of the proposed FE model. The predicted FE results are compared with the past experimental work for thrust force evaluation and burr formation on workpiece surfaces. The present work is supported with modal and harmonic analysis of stepped and conical horns along with micro drill bit. Here, horns made up of Aluminum 6061-T6, Titanium and Mild steel are chosen with micro drill bit of 0.3 mm diameter with varying tool materials (Tungsten carbide and High speed steel). The effects of natural frequencies with different mode shapes within the range of 15-30 kHz are shown. The frequency responses of micro drill with displacement conditions have been presented for longitudinal modes. The present simulation results will be helpful to conduct proper experimentation in order to achieve efficient machining and surface finish. The results enumerate that the drilling parameters have a strong influence on thrust forces and stresses occurring in micro-drilling. Ultrasonic assisted micro-drilling has a good potential in reduction of forces generated by vii selecting proper machining parameters. The FE simulation of UVA micro machining can further be enhanced and extended to various materials like plastics, sheet metal, other PCBs, etc. to predict the performance with varying machining and geometrical parameters

Improvements in ultrasonically assisted turning of TI 15V3Al3Cr3Sn

Titanium alloys have outstanding mechanical properties such as high hardness, a good strength-to-weight ratio and high corrosion resistance. However, their low thermal conductivity and high chemical affinity to tool materials severely impairs their machinability with conventional techniques. Conventional machining of Ti-based alloys is typically characterized by low depth of cuts and relatively low feed rates, thus adversely affecting the material removal rates (MRR) during the machining process. Ultrasonically assisted turning (UAT) is an advanced machining technique, in which ultrasonic vibration is superimposed on a cutting tool. UAT was shown to improve machinability of difficult-to-machine materials, such as ceramics, glass or hard metals. UAT employment in the industry is, however, currently lacking due to imperfect comprehensive knowledge on materials‘ response and difficulties in obtaining consistent results. In this work, significant improvements in the design of a UAT system were performed to increase dynamic and static stiffness of the cutting head. Concurrent improvements on depth-of-cut controls allowed precise and accurate machining operations that were not possible before. Effects of depth of cut and cutting speed were investigated and their influence on the ultrasonic cutting process evaluated. Different cutting conditions -from low turning speeds to higher recommended levelwere analysed. Thermal evolution of cutting process was assessed, and the obtained results compared with FE simulations to gain knowledge on the temperatures reached in the cutting zone. The developed process appeared to improve dry turning of Ti-15-3-3-3 with significant reduction of average cutting forces. Improved surface quality of the finished work-piece was also observed. Comparative analyses with a conventional turning (CT) process at a cutting speed of 10 m/min showed that UAT reduced the average cutting forces by 60-65% for all levels of ap considered. Temperature profiles were obtained for CT and UAT of the studied alloy. A comparative study of surface and sub-surface layers was performed for CT- and UAT-processed work-pieces with notable improvements for the UAT-machined ones. Two- to three-fold reductions of surface roughness and improvements of other surface parameters were observed for the UAT- machined surfaces. Surface hardness for both the CT- and UAT-machined surfaces was investigated by microindentation. The intermittent cutting of the UAT-process resulted in reduction of hardening of the sub-surface layers. Optical and electronic metallographic analyses of cross-sectioned work-pieces investigated the effect of UAT on the grain structure in material‘s sub-surface layers. Backscatter electron microscopy was also used to evaluate the formation of α-Ti during the UAT cutting process. No grain changes or α-precipitation were observed in both the CT- and UAT-machined work-pieces

Vibration assisted machining: Modelling, simulation, optimization, control and applications

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 30/11/2010.Increasing demand for precision components made of hard and brittle materials such as glasses, steel alloys and advanced ceramics, is such that conventional grinding and polishing techniques can no longer meet the requirements of today's precision manufacturing engineering. Particularly, in order to undertake micro-milling of optical glasses or other hard-machining materials, vibration assisted machining techniques have been adopted. However, it is essential and much needed to undertake such processes based on a scientific approach, i.e. the process to be quantitatively controlled and optimized rather than carried out with a trial-and-error manner. In this research, theoretical modelling and instrumental implementation issues for vibration assisted micro-milling are presented and explored in depth. The modelling is focused on establishing the scientific relationship between the process variables such as vibration frequency, vibration amplitude, feedrate and spindle speed while taking into account machine dynamics effect and the outcomes such as surface roughness generated, tool wear and material removal rate in the process. The machine dynamics has been investigated including a static analysis, machine tool-loop stiffness, modal analysis, frequency response function, etc, carried out for both the machine structure and the piezo-actuator device. The instrumentation implementation mainly includes the design of the desktop vibration assisted machining system and its control system. The machining system consists of a piezo-driven XY stage, air bearing spindle, jig, workpiece holder, PI slideway, manual slideway and solid metal table to improve the system stability. The control system is developed using LabVIEW 7.1 programming. The control algorithms are developed based on theoretical models developed by the author. The process optimisation of vibration assisted micro-milling has been studied by using design and analysis of experiment (DOE) approach. Regression analysis, analysis of variance (ANOVA), Taguchi method and Response Surface Methodology (RSM) have been chosen to perform this study. The effects of cutting parameters are evaluated and the optimal cutting conditions are determined. The interaction of cutting parameters is established to illustrate the intrinsic relationship between cutting parameters and surface roughness, tool wear and material removal rate. The predicted results are confirmed by validation experimental cutting trials. This research project has led to the following contribution to knowledge: (1) Development of a prototype desktop vibration assisted micro-milling machine. (2) Development of theoretical models that can predict the surface finish, tool wear and material removal rate quantitatively. (3) Establishing in depth knowledge on the use of vibration assisted machining principles. (4) Optimisation of cutting process parameters and conditions through simulations and machining trials for through investigation of vibration assisted machining.Financial support was obtained from Brunel University

MICRO-EDM-BASED MULTI-PROCESS MACHINING OF TUNGSTEN CARBIDE

Ph.DDOCTOR OF PHILOSOPH

Remanufacturing and Advanced Machining Processes for New Materials and Components

"Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems.

Remanufacturing and Advanced Machining Processes for New Materials and Components

Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems