Laser percussion drilling of coated and uncoated aerospace materials with a high beam quality and high peak power lamp pumped pusled Nd:YAG laser

Abstract

Listen

Translate article

Aerospace gas turbines require a large number of small diameter holes (<1mm) to provide cooling in the turbine blades, nozzle guide vanes, combustion chambers and afterburner. Many thousands of holes are introduced in the surface of these components to allow a film of cooling air to flow over the component. Laser percussion drilling with pulsed Nd: YAG laser is now a well-established material processing technique in the aerospace industry. The advantages of using pulsed Nd: YAG laser of being able to drill difficult materials, especially superalloys and thermal barrier coated superalloys (TBC).One of the major aspects that concern the aerospace industry is the quality of the drilled holes. Hole geometry such as taper, roundness and variation between holes must be within certain tolerances if the component is going to be used in an aero engine. Other important factors with respect to hole quality are metallurgical issues concerning recast layer and micro-cracking with in the hole.This paper investigates laser percussion drilling of high quality holes for the aerospace market with a new low cost high peak power up to 20kW and high beam quality (<4mm.mrad) pulsed Nd: YAG laser especially developed for aerospace market. Holes were drilled with various laser and processing parameters on coated and uncoated nickel based superalloy material to examine the hole quality in terms of recast layer, taper, oxidised layer and cracking etc.Aerospace gas turbines require a large number of small diameter holes (<1mm) to provide cooling in the turbine blades, nozzle guide vanes, combustion chambers and afterburner. Many thousands of holes are introduced in the surface of these components to allow a film of cooling air to flow over the component. Laser percussion drilling with pulsed Nd: YAG laser is now a well-established material processing technique in the aerospace industry. The advantages of using pulsed Nd: YAG laser of being able to drill difficult materials, especially superalloys and thermal barrier coated superalloys (TBC).One of the major aspects that concern the aerospace industry is the quality of the drilled holes. Hole geometry such as taper, roundness and variation between holes must be within certain tolerances if the component is going to be used in an aero engine. Other important factors with respect to hole quality are metallurgical issues concerning recast layer and micro-cracking with in the hole.This paper investigates la...