A production-scale multiwire saw machine and 4 inch sapphire ingots were used in this
study. The diamond wire used in the study had a core diameter of 0.1mm with an attached diamond
particle size of 8–12µm. This study uses the Taguchi method and Grey relational analysis on the key
diamond wire parameters which are electroplated nickel layer thickness, diamond wire tension,
diamond wire speed and sapphire ingot feed rate, in order to simultaneously optimize the cutting
performance in the diamond wire sawing of sapphire ingots. Based on the analysis, the nickel layer
thickness and wire speed are the first and second most significant factors with 31.7 and 29.9% effects
on cutting performances. The optimal control factors were then simultaneously evaluated for Ra,
material removal rate, diamond wire wear rate and TTV and were found at optimization to be 14 µm
nickel layer thickness, 15NT wire tension, 800m/min wire speed and 0.2mm/min feed rate,
respectively. Compared with current standard condition, this improved process obtained from the
optimization of diamond wire electroplated nickel layer thickness and saw machine parameters in the
diamond wire sawing of sapphire ingots can achieve a 33% lower Ra, a 20% lower diamond wear rate,
a 13% lower TTV and a 20% higher material removal rate, simultaneously.
