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

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

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

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

Ultrasonically-assisted drilling of carbon fibre-reinforced plastics

Carbon fibre-reinforced plastics (CFRP) are widely used in aerospace, automobile and other structural applications due to their superior mechanical and physical properties. CFRP outperform conventional metals in high strength-to-weight ratio. Usually, CFRP parts are manufactured near to net-shape;however,machining is unavoidable when it comes to assembly. Drilling the holes are essential to facilitate riveting and bolting of the components. However, conventional drilling (CD) induces different types of damages such as cracking, fibre pull-out, sprintling and delamination due to the abrasive nature, inhomogeneity and anisotropy of CFRP. A novel technique, ultrasonically-assisted drilling (UAD) is hybrid machining technique in which highfrequency (typically above 20 kHz) vibration are superimposed on a standard twist drill bit in axial direction using ultrasonic transducer. UAD has shown several advantages such as thrust force reduction, improving surface quality and lower bur-formation in drilling of conventional metals. UAD has also effectively been used for drilling brittle materials. [Continues.

A surgical bone biopsy needle using ultrasonic-sonic frequency vibration

This thesis presents a surgical needle designed for bone biopsy, based on an ultrasonic-sonic drilling mechanism. Bone biopsy is an invasive diagnostic procedure where a bone sample is extracted for clinical analysis. For conventional bone biopsy methods, closed biopsy is normally adopted and uses a core needle. An intact and viable biopsy sample is required for clinical analysis. However, a particular limitation of closed biopsy is that the microarchitecture of the biopsy sample can be easily damaged due to the large force which is applied through the core needle to penetrate bone. In some cases, the bone biopsy samples are fractured or crushed during the biopsy process. Power ultrasonic surgical devices have improved many aspects of bone cutting procedures, such as lower cutting force, higher accuracy, and better preservation of the tissue around the cutting site. In this study, an ultrasonic-sonic needle (US needle) system is designed and used to extract an intact biopsy sample and the penetration performance is evaluated by the effective impulse delivered to the target. The ultrasonic-sonic drilling mechanism was originally invented for rock drilling in low environments. In the US needle system, a free mass oscillates between an ultrasonic transducer-horn and a surgical needle, converting the ultrasonic frequency vibration of the horn to sonic frequency vibration of the needle. Compared to other ultrasonic surgical devices that directly transfer the ultrasonic vibrations from the cutting tip to the tissue, the US needle allows sufficient time between impacts with the free mass for the tip vibration amplitude to be re-established in the horn. This can maintain penetration progress of the needle into bone, where the rate of progress has been shown to be proportional to the effective impulse delivered by the needle to the bone. To maximise the effective impulse, a numerical model is developed to simulate the dynamic behaviour of the needle system and optimise the US needle. To build the US needle system, the design and optimisation of the ultrasonic transducer-horn were investigated with the finite element method and experimental modal analysis, ensuring that the transducer-horn operates at the tuned frequency (50kHz) with a pure longitudinal mode. The configuration of the ultrasonic horn determines the momentum transferred to the free mass and hence also affects the effective impulse delivered to the target. The shape and dimensions of the ultrasonic horn were determined through the finite element model of the ultrasonic horn impacting the free mass, which focused on maximising the post-collision velocity of the free-mass. The dynamic components of the US needle were also investigated. A numerical model representing the dynamic behaviour of the needle system was developed, allowing the optimisation of each dynamic component, maximising the effective impulse delivered to the target. Each dynamic component of the US needle was modelled as a mass-spring-damper (MSD) system, which constituted the whole system dynamic model. The numerical model was validated by experiments using a prototype needle. The free-mass velocity, needle velocity and impact force predicted by the numerical model were compared with the results measured from experiments using 3D laser Doppler vibrometry, an ultra-high speed camera and a load cell, respectively. The numerical model results exhibit good agreement with the experimental results, indicating the numerical model can be used as a predictive tool to evaluate the performance of the US needle when different configurations are implemented. The configuration of the US needle is studied to maximise the effective impulse by the numerical model, through optimisation of the mass of the free mass, spring rate and spring pre-load. An optimised configuration of the US needle was determined by the numerical model and validated by experiments. The resulting prototype of the needle device was tested in ovine femur in vitro and was demonstrated to retrieve a cortical bone biopsy sample with a more cylindrical geometry, smoother surface and more intact sample than a cortical biopsy sample retrieved using a conventional trephine needle. Moreover, the penetration performance of the US needle was also compared with an ultrasonic resonant needle where the ultrasonic transducer and surgical needle resonate at the same frequency

Study of Parameters of Ultrasonic Machining

The recent development of modern hi-tech industries has given rise to the creation of a whole range of new materials. These include high strength, stainless and heat resistant steels and alloys, titanium, ceramics,composites, and other nonmetallic materials. These materials may not be suitable for traditional methods of machining due to the chipping or fracturing of the surface layer, or even the whole component, and results in a poor product quality. Similarly, the creation of new materials often highlights some problems unsolvable in a framework of traditional technologies. In certain cases these problems are caused by the construction of the object and the requirements particular to it. As an example, in microelectronics, its often necessary to connect some components without heating them or adding any intermediate layers. This forbids the use of traditional methods such as soldering or welding. Many of these and similar problems can be successfully solved using ultrasonic technologies. The USD (Ultrasonic Drilling Machine) uses a novel drive mechanism to transform the ultrasonic or vibrations of the tip of a horn into a sonic hammering of a drill bit through an intermediate free-flying mass

Resonant ultrasonic bone penetrating needles

Bone biopsy is an invasive clinical procedure where a bone sample is recovered for analysis during the diagnosis of a medical condition. The procedure is performed while the patient is under either local or general anaesthesia as the patient can experience significant discomfort and possibly large haematoma due to the large axial and rotational forces applied through the needle to penetrate bone. It is well documented that power ultrasonic surgical devices offer advantages of low cutting force, high accuracy and preservation of soft tissues. This thesis details a study of the design, analysis and evaluation of a class of novel power ultrasonic needles for bone penetration, particularly biopsy. Micrometric vibrations generated at the distal tip of a full-wavelength resonant ultrasonic device are used to penetrate the bone. Both ultrasonic longitudinal (L) and longitudinal-torsional (L-T) coupled vibration have proven successful in several applications including ultrasonic surgical devices. Interest in ultrasonic bone cutting has grown since it was first introduced commercially as Piezosurgery in the 1990s. More recent studies have focused on precision cutting of bone, reducing the risk of damage to surrounding delicate tissues in comparison with manual and other powered instruments. Finite element analysis (FEA) is used to design full wavelength ultrasonic needle devices, where the geometry of the device is systematically modified to deter modal coupling by monitoring the frequency spacing between the longitudinal mode of interest and the neighbouring parasitic modes. FEA is further exploited to predict the achievable torsional displacement in a composite mode device tuned to vibrate in a longitudinal-torsional motion through degeneration of the longitudinal motion. While the L-mode device requires the operator to apply a slow backward and forward rotation and a small forward force, to maintain a forward motion and avoid imprinting, a L-T motion at the tip device could avoid this, simplifying the procedure, increasing precision and resulting in a cylindrical, less damaged hole surface. The dynamic behaviours predicted by FEA are validated through experimental modal analysis (EMA) demonstrating the effectiveness of FEA for the design of these devices. EMA is performed by exciting the ultrasonic needle device with a low power random excitation over a predetermined frequency range and measuring the vibration response using a 3D laser Doppler vibrometer (LDV) across a grid of points on the surface of the device. Harmonic analysis was used to investigate the behaviour of the devices at high excitation levels to capture the inherent nonlinearity of the tuned device. The response is captured using bi-directional frequency sweeps across the tuned mode of interest at increasing excitation levels. Ultrasonic surgical instruments typically require to be driven at high excitation levels to generate sufficient vibration amplitude to cut or aspirate tissue or seal vessels. The nonlinearities of the instrument and load presented by the target tissue result in resonance frequency shift, variation in the electric impedance and instability in the vibrational response which can negatively affect the efficacy of the instrument. A resonance tracking system was developed to monitor the voltage and current and adjust the frequency in real time to compensate for the frequency shift. Additional functionality was incorporated to allow modifications to the excitation signal shape and to enable power modulation techniques to be tested in a study of their effects on the rate of progression of the device in its target tissue. Prototype ultrasonic needle devices were evaluated in penetration tests conducted in bone mimic materials and animal bones. The devices recovered trabecular bone from the metaphysis of an ovine femur, and the biopsy samples were architecturally comparable to samples extracted using a trephine biopsy needle. The resonant needle device extracted a cortical bone sample from the central diaphysis, which is the strongest part of the bone, and the biopsy was of superior quality to the sample recovered by a trephine bone biopsy needle. The biopsy sample extracted by the resonant needle was architecturally uniform and cylindrical with an absence of chipping on the surface, suggesting that the biopsy was extracted with precision and control. To penetrate with the L mode device, the operator had to apply a slow backward and forward rotation and the small forward force, to maintain a forward motion. The rotation had to avoid imprinting of the needle tip in the bone, which otherwise resulted in the device stalling. However the L-T mode device, realised by incorporating helical cuts along the axial length, could penetrate the same animal bone sample only requiring the small forward force, hence simplifying the procedure for the operator. The L-T device also provided increased precision, resulting in a cylindrical, less damaged hole surface. Finally, a case study related to skull-based surgery is presented. The petrous apex is a pyramidal shaped structure at the anterior superior portion of the temporal bone and can be the location of tumours, cysts and lesions requiring diagnostic investigation. The petrous apex is challenging to access due to its medial location in the skull base and closeness to important neurovascular structures. An extended surgical approach removes the subject but is associated with morbidity and hence a minimally invasive procedure to access this site to retrieve a biopsy provides a valuable test case for the ultrasonic needle. Guided by the expertise and experience of an ear, nose and throat surgeon, the ultrasonic needle devices were modified and demonstrated in lab-based studies as a new technology for this bone penetration procedure

Micro-Electro Discharge Machining: Principles, Recent Advancements and Applications

Micro electrical discharge machining (micro-EDM) is a thermo-electric and contactless process most suited for micro-manufacturing and high-precision machining, especially when difficult-to-cut materials, such as super alloys, composites, and electro conductive ceramics, are processed. Many industrial domains exploit this technology to fabricate highly demanding components, such as high-aspect-ratio micro holes for fuel injectors, high-precision molds, and biomedical parts.Moreover, the continuous trend towards miniaturization and high precision functional components boosted the development of control strategies and optimization methodologies specifically suited to address the challenges in micro- and nano-scale fabrication.This Special Issue showcases 12 research papers and a review article focusing on novel methodological developments on several aspects of micro electrical discharge machining: machinability studies of hard materials (TiNi shape memory alloys, Si3N4–TiN ceramic composite, ZrB2-based ceramics reinforced with SiC fibers and whiskers, tungsten-cemented carbide, Ti-6Al-4V alloy, duplex stainless steel, and cubic boron nitride), process optimization adopting different dielectrics or electrodes, characterization of mechanical performance of processed surface, process analysis, and optimization via discharge pulse-type discrimination, hybrid processes, fabrication of molds for inflatable soft microactuators, and implementation of low-cost desktop micro-EDM system