Effect of the initial-flaw on crack-propagation in two-step cutting of monocrystalline sapphire
Effect of the initial-flaw on crack-propagation in two-step cutting of monocrystalline sapphire
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DOI：
10.1016/j.jmapro.2020.06.017
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发表时间：
2020-08
影响因子：
6.2
通讯作者：
H. Yoon;S. Kwon;A. Nagaraj;S. Min
中科院分区：
文献类型：
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作者：
H. Yoon;S. Kwon;A. Nagaraj;S. Min
虽然蓝宝石具有优良的上级多功能性能，但在加工过程中严重的表面/亚表面损伤限制了该材料的应用。已经做出了许多努力来通过利用延性切削来改善材料的可加工性。在此，除了努力控制材料行为之外，在蓝宝石的加工中还利用了由积极的粗切削和精细精切削组成的加工策略，以提高工艺产量。为了实现这一目标，需要研究材料中现有缺陷的影响，因为它们的形状和尺寸显著影响随后切割中的裂纹扩展。考虑到这一点，加工行为的主要和随后的切削分析方面的切割方向的每一个，和现有的裂纹的影响进行了调查，相对于晶体取向和应力的韧脆转变点。实验结果表明，现有的缺陷显着影响裂纹扩展在随后的切割，韧性切割制度的变化与不同的主和随后的切割方向的组合高达约2倍。基于实验结果，进行两步切削作为概念验证，以优化材料去除率。
Though superior multifunctional performances of sapphire, heavy surface/subsurface damage during the process limit applications of the material. Many efforts have been made to improve the machinability of the material, by utilizing the ductile-regime cutting. Here, in addition to the efforts on control of material behavior, machining strategies consisting of aggressive rough cutting and fine finish cutting were utilized in the machining of sapphire to improve the process throughput. To achieve this goal, it is required to investigate the effects of existing flaws in materials because their shapes and size significantly influence crack propagation in subsequent cutting. Considering this, machining behavior of primary and subsequent cutting was analyzed in terms of cutting direction of each, and the effects of existing cracks were investigated with respect to the crystal orientation and stress at the ductile-brittle transition point. Experimental results showed that existing flaws distinctively influence the crack propagation in subsequent cutting; the ductile cutting regime varied up to about 2 times with the combination of different primary and subsequent cutting directions. Based on the experimental results, a two-step cutting was performed as a proof of concept to optimize the material removal rate.