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Effusion cooled combustor designs for gas turbine engines offer improvements over traditional cooling approaches. The effusion technique, also known as transpiration, or multi-hole, employs minute cooling passages through the wall to be cooled. Effusion cooling provides increased cooling effectiveness, enabling higher performance. Additionally, effusion cooling offers manufacturing benefits, due to its simplicity of design, which result in decreased cost. The design also provides many challenges due to the enormous number of cooling holes required in an effusion cooled component. Candidates for hole drilling, laser and electron beam drilling, are compared with respect to methodology, equipment, hole characteristics, and economics.

The Garrett Engine Division of Allied-Signal Aerospace is one of a few aerospace companies which takes advantage of laser hardening's benefits and brings the process to the production floor within the restrictions of aerospace requirements. Important considerations for implementation are: equipment, safety, training, process control, and quality assurance. Garrett places special emphasis on material selection and part geometry concerns, and their effect on the success of the process. Garrett's primary applications of laser hardening are the surface hardening of AISI 4340 steels to case depths of approximately 0.5 mm, achieving hardness equivalent to HRc 55 to 59.