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During ultrasonic machining the continuous use of the same abrasive particles results in the decrease of their grain size and in a lower machining rate. Wear of the tool also takes place. Tool wear is controlled by such factors as type of abrasive, grit size, tool material, static load, cutting time and cross sectional area of the tool used. Their influence on tool wear is discussed.

This paper is written to describe the accuracy of ferreite cores which were mass-produced by ultrasonic machining. The result shows that the accuracy becomes lower according to the number of the times of regrinding of horns.

Thin foils of deformed superficial layers in 18-8 stainless steel produced by ultrasonic machining were prepared by electropolishing and their structure was examined by transmission electron microscopy. The main results obtained are as follows:1) Deformed superficial layers changed their structure from the surface to the interior successively; fracture, crystallites, plastic deformation, elastic deformation, matrix.2) In crystallites, dislocations were densely tangled and α-phase martensite was formed by transformation due to high-temperature plastic deformation. Though cracks found in crystallites had no preferred orientation, sometimes microcracks along the planes {111} were observed in a plastically deformed region.3) Some lattice defects, such as pile-ups and tangle of dislocations, stacking faults, stacking fault tetrahedra, were observed in a plastically deformed region. e-phase martensite was also recognized.

Results of experiments conducted to determine the dependence of the ultrasonic machining rate V in Ketos tool steel on the peak‐to‐peak amplitude 2ξ on the frequency of vibration f on the abrasive particle diameter d and on the ratio of the mass of abrasive to the mass of water used in compounding the slurry are given. It is shown that within the range under investigation the quotient V/2ξfd is a constant for a critical ratio of the mass of abrasive to that of water. It is also shown that events occurring within the volume of a cube having sides equal to d are of fundamental importance in the ultrasonic machining process. A phenomenological equation is derived from which the most probable machining rate can be calculated for the range under investigation.

In spite of the fact that ultrasonic machining has been widely used in industry, the mechanism of the process is far from being clear. This paper contains the results of the theoretical and experimental investigations into the physics of ultrasonic cutting carried out in the Acoustics Institute of the U.S.S.R. Academy of Sciences in recent years. The paper was presented at the 1964 symposium of the Professional Group on Sonics and Ultrasonics of the Institute of Electrical and Electronics Engineers

A model is proposed for the mechanism of material removal in ultrasonic machining. From this model and fundamental physical principles, a machining rate equation is derived for the special case where solid, circular tools are used in conjunction with a puddled slurry. A comparison of the predictions of the theory with the experimental data shows that the theory gives the correct relationship between the machining rate and the variables involved in the machining process. Suggestions for the improvement of the ultrasonic machining process are presented, and the method to be used in generalizing the theory is outlined. The poor reproducibility of the machining rate measurements is explained on the basis of the machining rate equation.

A preliminary investigation into the effect of ambient pressure on the ultrasonic machining process indicates that under certain conditions the rate of workpiece removal can be significantly increased. Ultrasonic machining of glass and cemented carbide was performed and the increase in the rate of removal for glass was found to be much greater than for the carbide.

This paper presents a brief description of various successful industrial applications that have been made of ultrasonics. The applications are divided into three broad groups: low, medium, and high power. In the low-power group are included reduction of friction, inspection, remote control, flaw detection, and other types of gauging and nondestructive testing. The medium-power group includes ultrasonic machining, soldering, medical therapy, liquid level indicators, and similar types of depth gauges and instruments. The high-power group includes precision cleaning, emulsification, dispersion of metals, metallurgical, bacteriological, and other chemical and physical processing applications. It is only natural that the lowand medium-power applications received first commercial acceptance, while the high-power applications advanced more slowly awaiting the development of low-cost high-power ultrasonic transducers and low-cost ultrasonic power supplies. These latter requirements are at present reasonably well met, which means that great increases in industrial high-power ultrasonic applications can be expected in the immediate future.

Data are presented for the ultrasonic machining rate in Ketos tool steel obtained by using rectangular tool tips having different perimeters and circular tool tips having different radii. It is shown that the pressure rather than the force maintained between the tool tip and the workpiece is pertinent in the ultrasonic machining process, and that the ratio C/A of the tool tip perimeter C to the tool tip area A is of importance. It is also shown that for rectangular and circular tool tips a critical machining rate V0 and a critical pressure P0 exists, the values of which are related to the ratio C/A by the two simple expressions V0 = 2ξνdM(C/A) and P0 = L(C/A), where 2ξ and ν are the peak to peak amplitude and the frequency of vibration respectively, d is the abrasive particle diameter, and M and L are parameters independent of 2ξ, ν, d, C or A. On the basis of the above two equations a phenomenological expression is derived which for circular and rectangular tool tips relates the machining rate in general...

Investigations are reported on the influence on removal rate of slurry liquid cavitation, low temperature, liquid metal, and stress corrosion embrittlement of the work material, tool vibration amplitude, grit size and method of application of slurry, and the influence of heat-treatment and applied stress conditions of the workpiece. From these studies it is postulated that there may be three basic mechanisms involved in the ultrasonic machining process—microchip removal and material displacement by plastic deformation, and particle removal by fracture.

In this paper mechanical vibrating system is assumed to be as follows : (1) Mechanical vibrators in ultrasonic machine are m-r-s series combination. (2) Ultrasonic load in machining consists of restoring stiffness and damping resistance, which differ in contact and in noncontact time respectively. Analytical results obtained from replacing nonlinear vibration above mentioned with its equivalent linear one are as follows :(1) The expression for contact angle in one cycle is given.(2) The expressions for restoring stiffness and damping resistance in contact time are given.(3) The expression for penetrating amount of abrasives into work piece, upon which machining volume depends is given.These expressions explain qualitatively the causes of (a) difference by kinds of work, (b) difference by size of abrasives and (c) the existence of the most suitable static pressure on ultrasonic machining speed.

以上,超音波加工における試料の厚さが加工量におよぼす影響についての実験および考察を要約すると次のようである。(1)試料の厚さが増大すると加工量は次第に減少しその厚さが試料中の音波の波長の1/4になると加工量は最小になる。(2)加工量が(1)のように最小になるのは工具振巾よりも衝撃力の減少が大きく関係し,衝撃力は試料厚さがλ/4付近で最小になつている。また加工量・衝撃力ともに送り力が大きい程その減少量は大きい。(3)衝撃力の変化は超音波エネルギの異質媒質への法線入射の反射および透過の理論値によく一致し,加工面でのエネルギの消費が加工量を左右する。

Until recently ultrasonic machining meant the hammer action of a tool tip which drives an abrasive into the workpiece and cuts out a hole in its own image. Now however new approaches are being tried. If, for example, a conventional lathe tool or milling tool is vibrated at about 20 kc/s it cuts faster and more smoothly and uses less power. The author has based this survey of all aspects of machining on his lecture to the conference “Ultrasonics for industry” held in London in September, 1964

Publisher Summary This chapter discusses modern fabrication techniques. Although most of the new machining processes have been developed specifically for materials that are difficult to machine, some of them have found use in the production of complex shapes and cavities in softer, more readily machined materials. Machining by the electrochemical or electrical discharge processes is confined strictly to metals, whereas ultrasonic machining may be applied to a much wider range of materials. Following are typical examples of the range of work covered by this process: (1) machining of ceramics and porcelain; (2) cutting glass including thread cutting; (3) cutting precious and semiprecious stones; (4) machining silicon, germanium, and other semiconducting materials; (5) machining ferrite; (6) machining small punches and dies for presswork; (7) machining accurately cavities of limited depth in cemented carbide; and (8) drilling holes of varied internal configuration. The development of this process has opened up several possibilities for the extended use of materials such as ceramics and semiconducting materials, which would hitherto have been impractical.

We have shown that the machining speed depends on the vibration amplitude, applied static pressure, abrasive concentration, and size distribution of the abrasive particles. If these parameters are held constant, the machining speed should not vary with depth of penetration of the tool. It is well known, however, that the speed decreases significantly with depth of the cut. This effect is clearly attributable to variation of the concentration or grain sizes of the abrasive in the working space under the tool. In the course of ultrasonic machining some of the abrasive grains are broken, and fresh ones take their place. Consequently, not only the number of particles, but also their sizes vary.

The usual ultrasonic machining processes use transducers operating at resonance and with a sinusoidal motion of the tip. Magnetostrictive transducers can be designed, however, with excitation applied sequentially along their length at a rate equal to the velocity of sound in the material. In this case, a steadily increasing strain pulse is produced, which travels in the direction of excitation. The motion of the tip has a large amplitude, short rise time, and is almost nonringing. The displacement can reach a few mils and large forces are generated if the tip is held against a solid object. The amplitude of the output and the repetition rate can be precisely controlled. The transducer was studied for applications such as rivetting, metal forming, and rock drilling. Another important use for this transducer with its short duration nonringing output signal is as a transducer in nondestructive testing. Two 7‐in. transducers and one 5‐ft‐long transducer were built. The 5‐ft transducer was used for dimpling me...

Results of experiments conducted to determine the dependence of the ultrasonic machining rate, V, in Ketos tool‐steel on the peak‐to‐peak amplitude, PPA, of the vibrating tool‐tip, on the frequency of vibration, f, of the tool‐tip, on the geometric weight mean diameter, rw, of the abrasive particles used in the make‐up of the slurry, and on the ratio, ma/mc, of the mass of abrasive to the mass of water vehicle used in compounding the slurry, are given. It is shown that the quotient V/rw PPA f is a constant of the ultrasonic machining process within the range under investigation, and that with its aid the contribution to the machining rate of a single abrasive particle can be calculated. On the basis of this investigation a possible model of the ultrasonic machining process is presented.

Before it was possible to produce an instrument which the dentist could safely use in his office, a number of physical and biological conditions had to be met. This paper presents a succinct account of the salient features of this development against the industrial background of precision ultrasonic machining from which it sprang. The physical performance of the ultrasonic drill itself will be discussed in the light of the demands of dentistry in removing tooth structure. From the biological point of view the effect of the drill on the human organism is paramount. A brief resume will be given of the status of this important topic and its relation to the technical design problems encountered. A comparison of the ranges of frequency encountered in medical therapy and dentistry will be included.

Ultrasonic machining of hard materials, such as cemented carbides, steel, sapphire, etc., requires the use of an acoustical transmission line. This line generally consists of a specially shaped solid body designed so as to convey the ultrasonic vibrations of the transducer to the tool which operates on the work piece. This paper deals with a general type of mechanical impedance transformer suitable for the above‐stated purposes. The theory has been cast in such form that the design of such lines may be made from universal equations and graphs. Because such equations appear in terms of ratios, one set of curves applies to all materials and to any desired frequency range. Several cases will be treated in detail so as to make the method employed clear. In addition examples will be given of actual transformers with an account of their performance in practical cases. As is the case generally with transformers, the systems described in this paper have applications in many cases where transformation of the ultra...

In order to gain a better understanding of the mechanism of ultrasonic machining, the ultrasonic machining rate has been measured on a number of solids having different physical properties. It has been found that a correlation exists between the measured machining rate and certain physical properties of the solid being machined. Two cases have been treated; namely, where the tool tip and workpiece are made of the same material, and where they are made of different materials. Empirical equations for the machining rate as a function of these physical properties have been obtained for both cases.

An electronically driven and controlled magnetostrictive transducer is used in conjunction with a suspended abrasive to machine hard, brittle materials such as ceramics and the carbide metals. The transducer has been constructed especially to supply high amplitude vibrations at the surface being machined. Data taken indicate that certain compromises must be made relative to cutting speed and tool wear. The effects of other variables such as vibration amplitude and abrasive size have been optimized for machining tungsten carbide, but no conclusions have yet been reached regarding the mechanism of ultrasonic machining.

Experimental results are presented which demonstrate the dependence of the ultrasonic machining rate in Ketos tool steel on variables associated with the ultrasonic machining process. These variables include the peak to peak amplitude and the frequency of vibration of the tool tip; the geometric shape of the tool tip; the pressure which is maintained between the tool tip and the work piece; the diameter of the abrasive particles and the ratio of the weight of the abrasive to the weight of the water vehicle used in compounding the slurry. An analysis of the experimental evidence makes it apparent that four constants are of fundamental importance in the ultrasonic machining process. One constant is a number representing the critical fractional part of an abrasive particle which is crowded into a cubic volume having sides equal to the abrasive particle diameter; another constant is the normal distance outward from the perimeter of the tool tip over which abrasive is effectively sucked underneath the tool tip...