Search

This paper reviews the development of ultrasonic surface treatment techniques, including ultrasonic shot peening, ultrasonic peening treatment, and ultrasonic surface rolling techniques. Ultrasonic surface treatment techniques are effective technologies to induce severe plastic deformation and improve the mechanical properties and surface integrity of components. In recent years, numerous researchers have explored various ultrasonic surface treatment techniques to improve surface integrity using available facilities and equipment. Besides, due to the limitations in industrial applications, these techniques are expanding to improve various surfaces with specific geometric shapes. Despite the wide range of techniques in this field, this review focuses solely on industrial applications based on cold working. This article briefly explains each technique and its advantages and disadvantages compared to other techniques. Applications of these techniques are presented with descriptive illustrations, and their effects on the surface characteristics of ferrous and non-ferrous materials are summarized. Based on this, the existing shortcomings and limitations are discussed in this paper, and prospects for ultrasonic surface treatment approaches in future studies are considered. The present review enhances the knowledge of ultrasonic surface treatment techniques and provides a quick reference for the appropriate usage of each technique in relevant applications. [ABSTRACT FROM AUTHOR]

The moulding process is a low-cost method for the mass production of microfluidic chips, rather than fabricating the chips one by one. The precision manufacturing of the mould is the key to the moulding process, which usually includes a combination of several machining processes. However, most of the current studies focus on a single process in microfluidic chip fabrication, which makes it difficult to optimise the fabrication process, resulting in low production efficiency and high energy consumption. Therefore, to realize the low cost and sustainable mass production of microfluidic chips, the process chain is developed in this paper. The process chain includes milling, precision ultrasonic vibration–assisted grinding, fluid jet polishing, and injection moulding. Parametric experiments regarding the key parameters of grinding, polishing, and injection moulding are conducted to obtain the optimization conditions. The form accuracy of the microchannel reaches 8.594 μm, and the roughness at the bottom surface of the microchannel is 0.027 μm. The experimental results demonstrate that the proposed process chain is effective and feasible for the mass production of microfluidic chips with high surface quality. It also provides some theoretical bases for the manufacturing of structured surfaces with nanometric surface roughness. [ABSTRACT FROM AUTHOR]

The reproducibility of vibration amplitude during insert mounting plays an important role in the controllability of the ultrasonic cutting process. In this study, a novel full wedge-type insert mounting method was developed to suppress the vibration instability induced by insert remounting. An ordinary threaded connection was selected as a counterpart to evaluate the performance of the proposed full wedge-type method through finite element model (FEM) by simulation and experiments. A theoretical model describing the effects of the connection interface on the vibration characteristics of the ultrasonic cutting system was established accordingly. Both the ordinary and full wedge-type threaded connection methods are shown to have a minimum threshold of screw pre-tightening torque, below which the self-relaxation and vibration disturbance of the cutting insert cause transmission failure of vibration energy and the insert itself. The pre-tightening torque threshold of a full wedge-type threaded connection is smaller than that of an ordinary thread connection. The full wedge-type threaded connection shows much less intense vibration amplitude fluctuations than the ordinary threaded connection during repeated insert mounting operations. These performance improvements can be attributed to contact force amplification effects on the wedge-type interface under the same effective pre-tightening torque under the proposed full wedge-type insert mounting conditions. [ABSTRACT FROM AUTHOR]

Ultrasonic elliptical vibration cutting (UEVC) is a superior machining method for difficult-to-cut materials. The shape of the elliptical tool trajectory crucially affects the integrity of the machined surface. However, the existing designs of UEVC tool typically suffer from difficult motion decoupling, resulting in the low controllability of elliptical trajectory. This study presents a new optimization design method of UEVC tool with dual longitudinal generators to create well-decoupled elliptical trajectory. A theoretical model which establishes the effects of key design variables on the tool resonant characteristics was adopted to optimize the configuration angle (the included angle of two longitudinal generators) as 90°. The structural parameters of the connection blocks of the two generators were also optimized to achieve resonance matching in both the normal (depth-of-cut) and tangential (cutting) directions. The optimized tool has a stable resonant frequency of 18 kHz, a working space of 5.1 μm × 5.3 μm, and a small trajectory error of less than 0.75 μm. The vibration measurement results showed that the optimized design can enable the high controllability of tool trajectory. Grooving experiments were conducted to verify the improved cutting performance of the designed tool due to the excellent control of tool trajectory. [ABSTRACT FROM AUTHOR]

Titanium alloy is a typical difficult-to-cut material due to its high strength and high stiffness. To solve the problem of the low efficiency and poor surface quality in the milling of titanium alloy, this paper proposes a novel longitudinal-torsional ultrasonic vibration milling (LTUVM) process. An ultrasonic horn with spiral slots was designed to convert the longitudinal vibration into longitudinal-torsional vibration. The tooltip trajectory was modeled, and the finite elements analysis was used to analyze the cutting mechanism of LTUVM. The simulation results indicate a kind of separation cutting characteristics in every vibration cycle, which is beneficial to reduce the cutting force and improve the surface finish compared with the single longitudinal ultrasonic vibration milling (SLUVM). Then, cutting tests were conducted on Ti-6Al-4V to evaluate the performance of LTUVM. Experimental results demonstrated that the LTUVM could reduce the cutting force by 46–86% compared with the conventional milling (CM) and the SLUVM due to its separation cutting characteristics. Moreover, the surface morphology was analyzed, and a fractal dimension (FD) method was proposed to characterize the regularity and fragmental property of the machined surfaces. The surface morphology analysis results showed that the LTUVM can be used as a novel high-efficiency and high-quality surface texturing method for Ti-6Al-4V. The textured surface of the LTUVM has the superiority of high integrity and periodicity, which could be applied to effectively tune the tribological property of surface. [ABSTRACT FROM AUTHOR]

A giant magnetostrictive rotary ultrasonic machine tool (GMRUMT) with a large and stable amplitude output was developed. The purpose of this study was to comprehensively evaluate the performance and technological characteristics of the GMRUMT by conducting large amplitude experiments of rotary ultrasonic machining. Combined with the transducers' characteristic curves of vibration amplitude versus frequency, the GMRUMT has the advantages of greater amplitude, higher power, and better stability compared with the conventional piezoelectric actuated rotary ultrasonic machine tool. The vibration stability of the GMRUMT during the machining process was evaluated by carrying out the rotary ultrasonic face milling of quartz glass and the measurement of the actual ultrasonic amplitude. The processing performance of the GMRUMT was evaluated by obtaining the cutting force, the critical feed rate, and the edge-chipping size at the exit hole via rotary ultrasonic drilling experiments. The tool life was evaluated by observing the abrasive wear of the tool. Finally, the GMRUMT was studied in a stable amplitude output condition via tuning to verify the machining advantages of the GMRUMT. [ABSTRACT FROM AUTHOR]

Beryllium is a rare metal with many excellent properties, which make it increasingly meaningful for manufacturing precise instruments especially in the aerospace industry. Most of the small size beryllium parts consist of microgrooves that play an important role during use. In this paper, we adopted electrochemical machining (ECM) technology to process sub-millimeter microgrooves successfully on beryllium. The influences of both the electrolyte and feed rate were analyzed in detail. As a result, sodium chloride (NaCl) electrolyte always causes strong pitting corrosion, while the ECMed surface is smoother with a low concentration of sodium nitrate (NaNO3). The cross-section of the microgroove is semi-elliptical. The depth decreases, and the width remains unchanged as the feed rate increases. Flow marks appear at the bottom as a result of the gas diffusion and cathode chattering. Electrolyte of 10% (mass fraction) NaNO3 and a feed rate of 10 mm/min were considered as the proper configuration to achieve a 350 μm × 56 μm microgroove on beryllium with a Ф320 μm stainless steel cathode. Finally, a structure with uniform microgroove width has been fabricated. [ABSTRACT FROM AUTHOR]

The mechanical machining induced edge chipping at hole exit restricts the applications of brittle materials. Rotary ultrasonic machining (RUM) is regarded as a suitable approach for the holes-manufacturing of brittle materials with reduced edge chipping, comparing with conventional grinding. However, obvious edge chipping can still be observed in RUM. In this research, a novel step diamond core drill for RUM was designed to further reduce the edge-chipping size. RUM tests on both quartz glass and sapphire were conducted to evaluate the effectiveness of this new type drill. Experimental results show that the step drill can reduce the edge-chipping size by approximately 60 % without bringing obvious bad influences on the tool life. The mechanism of edge-chipping reduction was revealed by the detailed observation of thrust force and theoretical analysis. In order to guarantee the effectiveness of step drill, the step thickness should be smaller than the thickness of drill end face and the step height should exceed a critical value. [ABSTRACT FROM AUTHOR]

Subsurface damage (SSD) induced by the rotary ultrasonic face machining (RUFM) considerably influences the technological application of the optical components. However, currently, there is no method to detect the depth of SSD in real time. For the purpose of precise and nondestructive evaluation of the SSD depth generated in RUFM processes, a predictive model was developed by applying the indentation fracture mechanics of brittle material. This was the first time that the correlation between the measured cutting force and SSD depth had been established. It was found that the SSD depth was directly proportional to the exponent of the measured cutting force (namely d = γF). Using this model, the depth of SSD could be predicted rapidly and precisely in the RUFM of optical glass even in real time using the measuring cutting force. Subsequently, this method was verified by conducting RUFM tests on K9 glass specimens with Sauer Ultrasonic 50. Meanwhile, the cutting force and SSD depth were compared experimentally between RUFM and conventional grinding (CG) process, indicating that RUFM is a beneficial manufacturing method for optical glass with reduced cutting force and SSD depth. [ABSTRACT FROM AUTHOR]

The progressive development of hard turning technology places greater demands upon clamping devices. The chuck is required not only to grip the workpiece securely but also to have high and stable radial chucking stiffness to guarantee high machining accuracy. As a primary property of a chuck, the clamping force, which greatly affects the security and precision of the machining process, must be meticulously determined. However, existing approaches for determining the required clamping force of jaw-chucks have mainly focused on their security. This is especially true for the crucial computation model for determining the critical bending force, which has more influence on the machining accuracy than other components of the cutting force. A new analytic computation model for determining the critical bending force of three-jaw power chucks, taking machining precision into account, is introduced in this study. The finite element method was applied and experiments performed to assist the modeling work. The results show that, when the jaw contacts the workpiece along its full clamping length, the variation in apparent radial chucking stiffness with respect to the direction of the bending force can be eliminated. In addition, an entirely uniformly distributed clamping force is desirable for the maintenance of larger critical bending forces, and a tiny negative initial angle is preferable. Furthermore, the critical bending force and radial chucking stiffness can be improved dramatically by enlarging the clamping length. This approach is helpful in the substitution of hard turning for grinding as the last process of machining. [ABSTRACT FROM AUTHOR]