**5.2 Grinding experiments**

The grinder installed fine feed and adjustment mechanisms was used to grinding microscale cylindrical workpiece, its aim is to verify the feasibility of micro-scale fabrication by ultrasonic-shoe centerless grinding technique, and to confirm the performance of the constructed experimental apparatus in actual grinding operations. The tungsten carbide steel cylindrical workpiece used in grinding is shown in Fig.17, 0.6mm in diameter and 15mm in length. The photo of grinder is shown in Fig.18 and Fig.19 shows a main portion of the experimental setup. The experimental conditions are listed as in Table 2.

Fabrication of Microscale Tungsten Carbide Workpiece by New Centerless Grinding Method 135

Amplitude *V*p-p=100V

Frequency *f*=24.3kHz

=7°

=60°

Phase difference 90

Grinding wheel speed *V*g=30m/s

Shoe feed rate *Vf* =0.1mm/min

Stock removal 0.4-0.55mm

Spark-out time 3 sec.

Fig.20 shows the SEM picture of the ground workpieces. Obviously, the cylindrical workpiece having an original diameter of 0.6mm slimed down to one having dimension of 60m in diameter, the aspect ratio of which is over 250. This result demonstrated that the constructed apparatus performed well even in actual micro-scale machining, and that micro-

Center height angle

Blade angle

scale fabrication by ultrasonic-shoe centerless grinding technique is feasible.

The grinding test was performed as follows: first, the gap between the right-down edge of the shoe and the top face of the blade was set up carefully using the fine vertical position adjustment mechanism so that the gap is smaller than the final diameter of the workpiece after grinding. Next, the grinding wheel was moved toward the blade and stopped soon after they have interfered with each other. Subsequently, the shoe was carried forward to feed the workpiece toward the grinding wheel at a feed rate of *Vf*=0.1mm/min and ground under the grinding conditions listed in Table 2. The grinding operation was finished once the given stroke removal and spark out had been completed and the shoe had been then

Grinding wheel SD2000150×20×76.2,1A1

Coolant Solution type

Input Voltage

Workpiece Tungsten carbide steel 0.6L15

retracted from the grinding wheel.

Grinding parameters

Geometrical conditions

**Table 2.** Conditions of grinding test

**Figure 17.** Original tungsten carbide steel cylindrical workpiece (D0.6mmL15mm)

**Figure 18.** Photo of grinder installed a fine feed and adjustment mechanisms

**Figure 19.** Experimental setup for the grinding test

The grinding test was performed as follows: first, the gap between the right-down edge of the shoe and the top face of the blade was set up carefully using the fine vertical position adjustment mechanism so that the gap is smaller than the final diameter of the workpiece after grinding. Next, the grinding wheel was moved toward the blade and stopped soon after they have interfered with each other. Subsequently, the shoe was carried forward to feed the workpiece toward the grinding wheel at a feed rate of *Vf*=0.1mm/min and ground under the grinding conditions listed in Table 2. The grinding operation was finished once the given stroke removal and spark out had been completed and the shoe had been then retracted from the grinding wheel.


#### **Table 2.** Conditions of grinding test

134 Tungsten Carbide – Processing and Applications

**Figure 17.** Original tungsten carbide steel cylindrical workpiece (D0.6mmL15mm)

**Figure 18.** Photo of grinder installed a fine feed and adjustment mechanisms

Diamond grinding wheel

Workpiece

Blade

Ultrasonic vibration shoe

**Figure 19.** Experimental setup for the grinding test

Fig.20 shows the SEM picture of the ground workpieces. Obviously, the cylindrical workpiece having an original diameter of 0.6mm slimed down to one having dimension of 60m in diameter, the aspect ratio of which is over 250. This result demonstrated that the constructed apparatus performed well even in actual micro-scale machining, and that microscale fabrication by ultrasonic-shoe centerless grinding technique is feasible.

Fabrication of Microscale Tungsten Carbide Workpiece by New Centerless Grinding Method 137

*School of Mechanical & Automotive Engineering Zhejiang, University of Science and Technology,* 

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**Author details** 

*Hangzhou, China* 

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**Figure 20.** SEM image of the ground tungsten carbide steel workpiece
