This paper applied Grey-Taguchi method to optimize the micro-drilling of PMMA polymer with multiple performance characteristics. The four parameters being optimized are coating layer, feed rate, spindle speed, and depth of cut. The performance of the dril This paper applied Grey-Taguchi method to optimize the micro-drilling of PMMA polymer with multiple performance characteristics. The four parameters being optimized are coating layer, feed rate, spindle speed, and depth of cut. The performance of the dril