Development of Punching Technology for Combustion Liners with Thermal Control Coatings

BACKGROUND: The efficiency of a contemporary gas turbine engines can be improved by increasing the operating temperature inside the engine, resulting in extreme thermal stress on materials. The temperature of combustion products inside aircraft engines can reach temperatures exceeding the melting points of the alloys used, limiting their applications. To protect working parts, thermal control coatings and cooling systems with punch holes are used. Laser perforation is a promising method that provides high precision and cost-effectiveness of hole punching processes for combustion liners with thermal control coatings. The development and improvement of such technologies is relevant for the aerospace industry and general mechanical engineering, where a balance between quality, performance, and cost is required. AIM: To develop an efficient laser perforation solution for combustion liners with thermal control coating, providing an optimal combination of precision, surface quality, and performance. The paper analyzes and compares existing punching methods to support the choice of the best possible technology. METHODS: The paper provides a technical analysis of existing perforation solutions for aerospace and general industrial applications. Punching options for combustion liners are considered based on data from open sources. The experimental part included the use of a serial five-axis laser processing machine SLP520 with a fiber laser. RESULTS: Analysis showed that laser perforation outperforms alternative methods in terms of accuracy and processing speed. Optimal laser radiation parameters ensure the lowest thermal effect on the thermal control coating and high repeatability. Experiments showed that a long-focus lens ensures fixed diameter and shape of the holes and a boron nitride protective paste helps prevent splashes around the holes. CONCLUSION: Laser perforation is an effective punching solution for cooling holes in combustion liners with thermal control coating. The proposed technology provides high precision, quality, and repeatability, making it preferable for aerospace applications. Further research may be aimed at studying the effect of protective paste on the thickness of the modified layer.