A novel Ultrasonic Machining for Micro Grooving
by means of a "Sandwich Tool"



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Micro grooves on the tool surface will provide various merits. For example,
(1) They can control the friction property at the tool-chip interface.
(2) They can control chip flow direction.
(3) They can stabilize cutting force, especially, the fluctuation of the thrust force can be reduced.

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Workpiece: 0.45% carbon steel, Cutting conditios:V=100 m/min, d=1.0 mm, f=0.25 mm/rev, WET


If the micro grooves corresponding to the circuit pattern for micro sensors can be fabricated on the cutting tool surface, the micro sensors for measuring temperature and force can be embedded into the grooves. We can know the temperature or stresses distributions at the tool-chip interface by means of these micro sensors. By using the information obtained by the sensors, we can control the tool wear and tool breakage by controlling the cutting conditions. Moreover, we can machine under the optimized cutting condition in which a free-cutting additive acts effectively.

As for the micro-grooving method, there are the laser beam machining, dry or wet etching. However, the running cost and the machine tool are very expensive.

Grooving method is a processing method that has been carried out from several thousand years ago. In ancient times, the grooves was fabricated by forcing sand on the workpiece. Sand is the abrasive. The sand (abrasive) scratches the surface of the workpiece. The surface is removed step by step. The more the number of times for scratching, the more the efficiency is enhanced. Thus, nowadays, the ultrasonic has been employed. This is the ultrasonic machining

In the ultrasonic machining, a slurry that the abrasives and liquid are mixed is supplied between a tool and a workpiece. The tool is vibrating at a ultrasonic frequency. The energy of the ultrasonic vibration is transmitted to the abrasives through the ultrasonic tool. The abrasive collides with the workpiece and scratch the surface of the workpiece. Thus,the the surface of the workpiece is removed corresponding to the shape of the tool surface.

Therefore, if the cross-section of the ultrasonic tool can be formed to the shape of the micro grooves, the micro grooves can be fabricated by ultrasonic machining. However, the stiffness of the ultrasonic tool becomes weak, if the shape of the cross section of the ultrasonic tool forms to the shape of the micro grooves A hard material can transmit the energy of the ultrasonic vibration to the abrasive efficiently. On the other hand, a soft material absorbs the energy of the ultrasonic vibration. Thus the soft material cannot transmit the energy of the ultrasonic vibration to the abrasive. The soft material for applying to the ultrasonic tool is not effective for grooving. It, howebver,can contribute to the support of the enhancing the stiffness of the ultrasonic tool. The stiffness of the ultrasonic tool can be enhanced by laminating the hard material and the soft material. By means of this lamination tool, the micro grooving can be fabricated by ultrasonic machining.

In this study, we call this lamination tool "Sandwich tool".


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Ultrasonic tool, Japan patent P5477784 (2014.2.21)

Inventor: Jun Shinozuka

The stainless shim sheet of 20 to 100 microns thick can be used for the hard material. Epoxy adhesive can be used as the soft material. Both the material are commercially available, and the cost of them are reasonable. The width of the micro groove can be controled by the thickness of the shim sheet. The interval between the micro grooves can be controlled by the thickness of the soft material in which the adhesive is impregnated into a tissue paper. The sandwich tool is handmade. The some technique is required for making the sandwich tool. But, once you get used to a little, you can create it in a good accuracy.

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Currently, we have been making an intelligent cutting tool that has micro thermocouples on the rake face by means of this method.

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This intelligent tool can measure the temperature distribution at the tool-chip interface during cutting!

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