Ultrafast Laser System for Drilling and Inspecting Straight and Shaped Cooling Holes

Cooling holes in turbine fan blades is a key element in proper jet engine function. Drilling of these holes with current technology can be costly and difficult leading to (a) not enough holes, (b) holes without the proper shape, and (c) defects in the thermal barrier coating resulting from post processing. ps Lasers have been shown to make very nice shaped holes in the primary material, Hastelloy-X, while maintaining the integrety of the thermal barrier coating. However, ps pulses lack the high intensity to greatly reduce the machining time, or are incapable of mm depth scales. Femtosecond pulses do not have any of these limitations, and have enough intensity to drill to cm depths. Also due to the broadband nature of femtosecond pulses, Optical coherence tomography (OCT) may be used for monitoring depth and possibly the shape of the hole drilled. BENEFIT: With rising gas prices, energy savings are critical. Better cooling holes in turbine fan blades may increase fuel economy for all military, and potentially commercial aircraft. Small gains in efficiency can have a high dollar value per year in total fuel consumption. This work may also bring a new capability to manufacturing in general by using the laser that cuts to monitor the surface as the feature is being made. This capability may have wide application to many different fields.