Turning of Machinable Ceramic Materials

1. Tool material and angle

When using ordinary cutting tools to process ceramics, the tool wear is fast, resulting in poor dimensional consistency of the parts, large machining surface taper, and easy cracking of the parts. Therefore, it is particularly important to choose a reasonable tool material. Generally speaking, because high-speed steel tools are prone to rapid wear of the tool tip during the cutting process, for the turning of glass ceramic materials, hard alloy tools with high hardness and strong wear resistance should be selected first. At the same time, hard alloy tools can apply higher cutting speeds, and the allowable cutting speed of general hard alloy tools can reach three times that of high-speed steel tools.

The preferred tool parameters are as follows: when rough turning the outer circle, the tool rake angle should be taken as -3 ° to 0 °; When precision turning the outer circle, the tool rake angle is taken as a small positive value, and the value is slightly increased to 0 °~2 °. In addition, the back angle of the tool is approximately 5 °, providing the required clearance. When using the above parameter values to process machinable ceramics, the tool is wear-resistant, the processing quality is stable, and the parts are not easy to crack. However, the service life of the tool during precision turning is shorter than that during rough turning.

2. Cutting parameters

Choosing reasonable processing parameters is very important as it can extend the service life of cutting tools, improve the processing quality and efficiency of parts. In the orthogonal experiment of machinable ceramic materials, the preferred parameters are as follows: when rough turning the outer circle, the cutting speed is 15 m/min; When finishing the outer circle, the cutting speed decreases to 10m/min. When machining with these parameter values, the machining quality is stable and the tool is relatively durable.

The impact of cutting depth on machining quality and tool durability is relatively small, and the maximum cutting depth for machinable glass ceramics can reach 6 35mm. In the orthogonal experiment, the preferred parameter to be selected is: when rough turning the outer circle, a larger cutting depth of 1 5-4mm; When precision turning the outer circle, the cutting depth value is reduced to 0.02mm, and the recommended value range is 0 02-0.1mm.

Excessive feed rate can also cause a decrease in the surface quality of the machined parts, so the feed rate should be taken as a smaller value. When cutting machinable ceramic materials, if the feed rate is greater than 0 2286mm/r, severe cracking may occur on the working surface. In the orthogonal experiment of machinable ceramic materials, the preferred parameter is: when rough turning the outer circle, the feed rate is 0 15 mm/r; When precision turning the outer circle, high machining accuracy is required, and the feed rate is small, with a value of 0.06mm/r.

In summary, under the premise of the same tool material, the values of cutting speed, feed rate, and cutting depth are not determined by a single factor, and should be comprehensively selected based on factors such as machining method, machining process requirements, and part material.

3. Cooling

For different machinable ceramic materials, selecting reasonable cutting parameters such as cutting amount, tool angle, and cooling is crucial for obtaining qualified machining quality. Due to the low thermal conductivity of machinable ceramics, a large amount of cutting heat is generated during the cutting process, which can easily cause parts to crack and break. At the same time, it can also rapidly increase the temperature of the tool, leading to tool wear and a decrease in cutting ability.

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