A comparative study on machinability of ceramics with different mechanical properties in diamond wire sawing

Abstract

Ceramics thin substrates are widely used in electronic devices due to their excellent physical and mechanical properties. Diamond wire sawing is one of promising manufacturing route to prepare thin ceramic substrates from sintered ceramics block. In present paper, a comparative study on diamond wire sawing of Al₂O₃, AlN, ZrO₂ and Si₃N₄ ceramics was carried out. The material removal rate (MRR), wire sawing force and surface integrity of different ceramics as well as the wear characteristics of diamond wire were examined. A finite element model (FEM) for the single-grain cutting of different ceramic materials was developed to elucidate the influence of the mechanical properties of these ceramics on both surface morphology and the cutting force. The results show that mechanical properties of ceramic materials have great influence on diamond wire sawing performance. The Al₂O₃ and AlN with lower fracture toughness exhibit better machinability than that of ZrO₂ and Si₃N₄. AlN has the highest MRR (0.128 mm³/min) and the smallest tangential sawing force (0.0255 N), while Si₃N₄ presents the lowest MRR (0.101 mm³/min) and ZrO₂ owns the largest wire sawing force (0.238 N) under wire speed of 1.3 m/s. For the sawn surface of ceramics, Si₃N₄ shows the lowest surface roughness (Ra 0.23 μm), followed by ZrO₂ (Ra 0.44 μm) and AlN (Ra 0.57 μm), while Al₂O₃ exhibits the highest surface roughness (Ra 0.62 μm). In sawing of ZrO₂ and Si₃N₄, the electroplated diamond grits tend to flatten or fall-off, producing severer wear of diamond wire than that of Al₂O₃ and AlN, and deteriorating the sawing capability of the diamond wire.