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

Abstract

H yb rid C 0 2 L a s e r/W a te rje t M a c h in in g of P o ly c ry s ta llin e D ia m o n d S u b s trate : M a te ria l S e p a ra tio n T h ro u g h T ra n s fo rm a tio n In d u ced C o n tro lle d F ra ctu reThis paper presents a combined experimental and computational investigation o f a novel material separation mechanism in polycrystalline diamond (PCD) substrates. A hybrid CO 2 laserlwaterjet (C 02-LWJ) machining system that combines a C 0 2 laser fo r localized heating and an abrasive-free water je t to rapidly quench the heated area is utilized fo r cut ting 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 sub strates were cut through a "score and snap" mechanism-laser heating leads to localized damage and phase transformation o f surface layers; and subsequently, stress fields devel oped due to constrained expansion o f transformed material and waterjet quenching act on the laser made "score" to propagate crack through the thickness. Analytical solutions fo r thermal diffusion and force equilibrium are used to determine the temperature and stress fields in the PCD substrate during C 0 2-LWJ cutting. Fracture mechanics analysis o f crack propagation is performed to demonstrate the feasibility o f the "score and snap" mechanism fo r cutting o f PCD substrates.

Laser Processing of Hard and Ultra-Hard Materials for Micro-Machining and Surface Engineering Applications

“…In special instances, nano-scale features can be made, and these are known as laser induced periodic surface structures (LIPSS) [ 53 ]. Common defects associated with PLA are melt debris, allotropic transitions, heat affected zones (HAZ), recast layer, porosity, and cracking ([ 54 , 55 ]) ( Figure 6 ). HAZ is a result of excess heat conduction causing regions of the microstructure to be heat-treated, giving rise to anisotropic properties [ 56 ].…”

Splitting Opaque, Brittle Materials with Dual-Sided Thermal Stress Using Thermal-Controlled Fracture Method by Microwave

“…It can achieve high splitting efficiency (its splitting speed can reach more than 10 mm/s) and good fracture quality (its arithmetic mean deviation of contour (Ra) can reach less than 10 nm) [3]. Therefore, the TCFM has obvious advantages compared with conventional cutting techniques such as abrasive wheel cutting, diamond saw cutting, abrasive water jet machining, ultrashort pulse laser beam ablation methods and other processing method [1,[4][5][6][7], and Crystals 2022, 12, 801 2 of 18 has become a promising machining method, attracting the interest of many researchers in the field of brittle material processing [8][9][10][11][12]. The thermal stress used to split material in the TCFM is produced by a heat source on the surface or in the body of the workpiece (as shown in Figure 1).…”

A study of hybrid laser–waterjet micromachining of crystalline germanium

“…By contrast, applying a waterjet at a small offset distance from the laser beam can overcome the issues that the laser-microjet experiences. This off-axial method was used in the laser thermal shocking process 18,19 where a CO 2 laser for localized heating and a waterjet for rapid quenching were used to crack and remove the materials. The low-pressure waterjet was located at a small distance from the laser beam to realize the laser thermal shocking process so that the cutting purpose can be achieved through the initiation and development of cracks on brittle materials.…”