Compared to conventional machining (CM), ultrasonic vibration-assisted machining (UVAM) with high-frequency and small-amplitude has exhibited good cutting performances for advanced materials. In recent years, advances in ultrasonic generator, ultrasonic transducer, and horn structures have led to the rapid progress in the development of UVAM. Following this trend, numerous new design requirements and theoretical concepts have been proposed and studied successively, however, very few studies have been conducted from a comprehensive perspective. To address this gap in the literature and understanding the development trend of UVAM, a critical overview of UVAM is presented in this study, covering different vibration-assisted machining styles, device architectures, and theoretical analysis. This overview covers the evolution of typical hardware systems used to achieve vibratory motions from the one-dimensional UVAM to three-dimensional UVAM, the discussion of cutting characteristics with periodic separation between the tools and workpiece and the analysis of processing properties. Challenges for UVAM include ultrasonic vibration systems with high power, large amplitude, and high efficiency, as well as theoretical research on the dynamics and cutting characteristics of UVAM. Consequently, based on the current limitations and challenges, device improvement and theoretical breakthrough play a significant role in future research on UVAM.

Review of ultrasonic vibration-assisted machining in advanced materials

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Advanced Modeling and Optimization of Manufacturing Processes

Rotary ultrasonic machining (RUM) is a mechanical type of nontraditional hybrid machining process that 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, the basic material removal phenomenon of ultrasonic machining (USM) and conventional diamond grinding amalgamates together and results in higher material removal rate (MRR), 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 performa...

Rotary Ultrasonic Machining: A Review

This study is carried out to investigate the material removal characteristics in elliptical ultrasonic assisted grinding (EUAG) of monocrystal sapphire using single diamond abrasive grain. The scratching experiments are performed to develop a fundamental understanding of the ductile–brittle transition mechanism during EUAG of monocrystal sapphire. An elliptical ultrasonic vibrator attached with a sapphire substrate was set up on a multi-axis CNC controlled machining center equipped with a single point diamond tool. The vibrator was constructed by bonding a piezoelectric ceramic device (PZT) having two separated electrodes on a metal elastic body, and an elliptical ultrasonic vibration was generated on the end-face of the metal elastic body when two phases of alternating current (AC) voltages with a phase difference are applied to their respective electrodes on PZT. In scratching experiments, the effects of ultrasonic vibration on the critical depth of cut a c for the ductile–brittle transition region and the material removal ratio, i.e., the ratio of the removed material volume to the machined groove volume, f ab , are investigated by the examination of the scratching groove surfaces with SEM and AFM. The obtained results show that the critical depth of cut in EUAG is much larger than that in conventional grinding without vibration (CG), and even the bigger vibration amplitude leads to a greater improvement. Although the values of f ab in the ductile–brittle transition region in both EUAG and CG are less than 1, that in EUAG is bigger than that in CG. Furthermore, as the vibration amplitude increases, the value of f ab is increased to eventually be close to 1. These show that it is prone to achieve a ductile mode grinding in greater vibration amplitude. It was also found that in the process there are two kinds of material removal modes, i.e., continuous cutting and discontinuous cutting modes, which are determined by the relationship between values of vibration amplitude and depth of cut. This study validates that the elliptical ultrasonic assisted grinding method is highly effective in ductile mode machining of hard and brittle materials.

Experimental study on brittle–ductile transition in elliptical ultrasonic assisted grinding (EUAG) of monocrystal sapphire using single diamond abrasive grain

An investigation on wear mechanism of resin-bonded diamond wheel in Elliptical Ultrasonic Assisted Grinding (EUAG) of monocrystal sapphire

Effects of process parameters on workpiece roundness in tangential-feed centerless grinding using a surface grinder

In our previous work, a new method for inducing a machine spindle to ultrasonically vibrate was proposed in which the axial ultrasonic vibration is excited by a fluctuating electromagnetic force applied to the spindle. The validity of this method was also confirmed experimentally. In this paper, focusing on the development of a new rotary ultrasonic spindle based on this new method, an actual ultrasonic spindle unit was designed and constructed in accordance with the previous work. The unit consists of an ultrasonic spindle, two rotary bearings and their housings for holding the spindle, eight electromagnets and their supporters for the generation of a fluctuating electromagnetic force, and a base plate. Its performance was also investigated experimentally for different exciting conditions. The results showed that an ultrasonic vibration with a sub-μm order amplitude is generated on the produced spindle and that the applied electromagnetic force affects the spindle performance significantly.

Development of a new rotary ultrasonic spindle for precision ultrasonically assisted grinding

An elliptical ultrasonic assisted grinding method is proposed for the machining of sapphire substrate in order to improve the machining efficiency and the work-surface quality. An elliptical ultrasonic vibrator is designed and produced by bonding a piezoelectric ceramic device (PZT) on a metal elastic body. The sapphire substrate is fixed onto the top face of the vibrator and ultrasonically vibrates in two dimensional (2D) vibration mode when the PZT is excited by two alternating current voltages with a phase difference. Grinding experiments are carried out with lateral modulation of elliptical vibration vertical to grinding speed direction. Experimental results show that grinding forces decrease significantly by 30% and grinding force ratio is reduced and surface roughness is improved by 15%, moreover surface fractures and cracks decrease obviously by using vibration compared with those of conventional grinding. These demonstrate that two-dimensional ultrasonic grinding is effective for high performance machining of sapphire substrate.

A feasibility study on elliptical ultrasonic assisted grinding of sapphire substrate

The characteristics of surface formation in elliptical ultrasonic assisted grinding (EUAG) of monocrystal silicon were investigated by grinding and single abrasive scratching experiments. In grinding experiments, an elliptical ultrasonic vibrator, on which a thin sheet shaped monocrystal silicon substrate was attached, was installed on a CNC surface grinder equipped with a diamond grinding wheel. By contrast, the vibrator attached with the substrate was set up on a multi-axis CNC controlled machining centre equipped with a single diamond tool to perform the scratching tests. The obtained results show that the grinding forces are reduced by 30%, the surface quality is improved significantly and the surface roughness is decreased by around 25% during EUAG compared with those in conventional grinding without ultrasonic vibration. There is a transition of material removal mode from the permanent contact to the unsuccessive contact between workpiece and abrasive by increasing the ratio of ultrasonic vibration amplitude to the depth of cut.

Weimin Lin

Papers

Effects of process parameters on workpiece roundness in tangential-feed centerless grinding using a surface grinder

Development of a new rotary ultrasonic spindle for precision ultrasonically assisted grinding

A feasibility study on elliptical ultrasonic assisted grinding of sapphire substrate

Surface formation characteristics in elliptical ultrasonic assisted grinding of monocrystal silicon