Micro-Drilling of Precision Flat Bottom Holes in Titanium

In Non Destructive Testing (NDT) ultrasonic flaw detectors are extensively used for inspection of metallic raw materials like forgings, castings and rolled sections for internal imperfections and defects like cracks, voids, inclusions etc. In these Ultrasonic flaw detectors Ultrasonic standard reference blocks are used as masters for allowable level of flaws in metallic raw materials. These reference blocks are also used for calibration of flaw detectors. These reference blocks are made with precisely drilled flat bottom holes (FBH) of different diameters depending on the allowable level of flaws. Reference blocks with flat bottom holes of dia from 2 mm down to dia 0.5 mm are mainly used in aerospace applications. These blocks are to be made in the same material that is to be inspected. The typical test materials are Aluminium, Steel, Titanium and Nickel base alloys. This paper deals with micro-drilling of 0.5 mm diameter flat bottom holes in Titanium material Ultrasonic Standard Reference Blocks.