Design and validation of a hybrid laser/water-jet machining system for brittle materials

Abstract

A unique laser/water-jet (LWJ) cutting head has been designed, built, and interfaced with a CO2 laser for cutting and scribing of hard and brittle ceramic materials. Alumina samples were used to validate the effectiveness of the LWJ cutting head in thermal fracture mode. The results were compared with vaporization mode (focused beam) as well as thermal fracture mode (defocused beam) of air-assisted laser cutting. The thermal fracture mode in both LWJ and air-assisted laser cutting required three to five times less energy input for material separation than the vaporization mode. However, the quality of the cut surfaces of the LWJ was superior to both vaporization and thermal fracture modes of air-assisted laser cutting in terms of kerf, recast zone, density of microcracks, undercutting, and spatter. The synergistic effects of laser and water-jet facilitated precise material separation and better cut quality through: thermal shock-induced fracture mode of material separation rather than energy-intensive erosive wear (water-jet alone) or melting and subsequent evaporation (laser alone); and expulsion of cracked material with kinetic energy associated with the water-jet, leaving a clean cut surface.

Hybrid CO2 laser/waterjet (CO2-LWJ) cutting of Polycrystalline Cubic Boron Nitride (PCBN) blanks with phase transformation induced fracture

“…The modified laser head of the CO 2 -LWJ system is shown in Fig. 1 and details of its design have been previously reported [6][7][8]. The laser head that incorporates the waterjet ensures that the workpiece is first irradiated with a CO 2 laser beam for localized heating and subsequently, the heated spot is rapidly quenched with the trailing waterjet.…”

“…Crack propagation provides an energy and cost efficient method for cutting of ceramics because hardness and brittleness of ceramics lead to low material removal rates and slow cutting speeds during conventional machining processes. In low thermal conductivity ceramics such as alumina thermal shock induced fracture has been successfully utilized for energy efficient cutting [6,7]. However in high thermal conductivity ceramics such as Polycrystalline Cubic Boron Nitride (PCBN), thermal shock may not be feasible.…”

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

“…1. In order to implement the C 0 2-LWI machining process, an existing laser machining head has been modified to accommodate the low-pressure abrasive-free w aterjet (<7M Pa (1000 psi)) [3]. In this hybrid process, a laser beam is used for localized heating of the sample surface and an abrasive-free waterjet is used to rapidly quench the heated area.…”

“…In low thermal conductivity materials, thermal shock induced fracture has been proposed for glass [ I ] and thin ceramic wafers [2] and demonstrated for energy efficient cutting of alumina and zirconia [3][4][5][6]. In low thermal conductivity materials, thermal shock induced fracture has been proposed for glass [ I ] and thin ceramic wafers [2] and demonstrated for energy efficient cutting of alumina and zirconia [3][4][5][6].…”

“…In the current work, a C 02-LWJ machining system was used to investigate a novel mechanism for cutting of PCD compacts through controlled fracture rather than energy intensive erosion or ablation of material [3][4][5][6][19][20][21]. Cut surfaces were analyzed to identify the mechanism governing material separation.…”