Product Code: ICAL08_305

Laser Drilling with Gated High Power Fiber Lasers
Authors:
John Washko, Connecticut Center for Advanced Technology; East Hartford CT USA
Paul Denney, Connecticut Center for Advanced Technology; East Hartford CT USA
Terri A. Marsico, Connecticut Center for Advanced Technology; East Hartford CT USA
Presented at ICALEO 2008

Flash-lamp pumped Nd:YAG lasers are presently used to percussion drill film cooling holes in gas turbine engine components. These lasers are the most popular lasers for cooling hole drilling because their characteristics result in acceptable processing times and microstructures. These lasers are used to drill through a wide range of material types and thicknesses and produce a range of hole diameters suitable for surface film cooling. However, the cost of inconsistent quality, non-value added operations, and increased expected engine performance have driven the need for development of next generation laser drilling technologies. Until recently, fiber delivered lasers did not have high enough average output power levels and/or energies to percussion drill holes acceptable holes. With the development of Yb fiber lasers there has been an interest in whether these lasers have the capability and/or advantages in aerospace percussion drilling applications. These continuous wavelength (CW) fiber lasers can be gated to produce short pulse durations at high repetition rates. The fiber lasers uniform power distribution, fiber delivery, and low operating/maintenance costs may justify using these lasers versus the Nd:YAG for drilling. The Connecticut Center for Advanced Technology (CCAT) has been examining the use of a 10 kW fiber laser for drilling. This paper will present some of the initial results of percussion drilling with comparison to traditional Nd:YAG lasers. The paper will also discuss what improvements may be needed to the fiber laser if it is to be used in aerospace applications.