Hybrid CO2 Laser/Waterjet Machining of Polycrystalline Diamond Substrate: Material Separation Through Transformation Induced Controlled Fracture

作者：Kalyanasundaram Dinesh; Schmidt Andrea; Molian Pal; Shrotriya Pranav^*

来源：Journal of Manufacturing Science and Engineering, Transactions of the ASME, 2014, 136(4): 041001.

DOI：10.1115/1.4027304

• thermochemical machining
• crack propagation
• polycrystalline diamond (PCD)
• CO2-laser/waterjet machining (CO2-LWJ)
• diamond-to-graphite transformation
• crack propagation

This paper presents a combined experimental and computational investigation of a novel material separation mechanism in polycrystalline diamond (PCD) substrates. A hybrid CO2 laser/waterjet (CO2-LWJ) machining system that combines a CO2 laser for localized heating and an abrasive-free waterjet to rapidly quench the heated area is utilized for cutting experiments on PCD substrates. Scanning electron microscopy (SEM) and micro-Raman spectrometry characterization performed on the cut surfaces show that cut surfaces were divided into two zones-a thin transformed zone near the top where the PCD grains have transformed to graphite and diamond-like carbon; and a fracture zone with the same composition as-received substrate. The experimental results indicate that the PCD substrates were cut through a %26quot;score and snap%26quot; mechanism-laser heating leads to localized damage and phase transformation of surface layers; and subsequently, stress fields developed due to constrained expansion of transformed material and waterjet quenching act on the laser made %26quot;score%26quot; to propagate crack through the thickness. Analytical solutions for thermal diffusion and force equilibrium are used to determine the temperature and stress fields in the PCD substrate during CO2-LWJ cutting. Fracture mechanics analysis of crack propagation is performed to demonstrate the feasibility of the %26quot;score and snap%26quot; mechanism for cutting of PCD substrates.

• 出版日期2014-8