Automatic laser inspection of outer diameter, run-out and taper of micro-drills

Abstract Micro-drills are best suited for small hole machining in view of its low cost and wide applications. The dimensions of micro-drills have a significant influence on the accuracy of the machining results and the life-span of the micro-drills. Hence, micro-drills, be they new or re-sharpened ones, must be inspected prior to use. Because the outer diameter of the micro-drills is small (0.5–0.1 mm), it is not easy for inspection to be done manually. This study employed the Laser Micro Gage (LMG) to measure the outer diameter of micro-drills as well as the degree of run-out and taper. Compared with the results obtained manually, measurements made by this automatic inspection system are faster and more accurate, achieving a precision within 0.1 μm.