ADVANCED MATERIALS & PROCESSES | APRIL 2025 24 As aero engine and land-based gas turbine manufacturers continue to pursue improved fuel efficiency and reduced emissions, engines are required to operate at ever higher temperatures. In response, design engineers are pushing for more aerodynamic geometries, complex cooling schemes, and improved materials performance. In this challenging scenario, Howmet Aerospace is one supplier that is delivering solutions based on advanced investment casting techniques—from controlling grain structure, dimensions, and material properties to enabling novel internal cooling designs. TECHNICAL SPOTLIGHT INVESTMENT CASTING INNOVATIONS FOR AEROSPACE AND BEYOND Single crystal and directionally solidified casting processes are among the most complex techniques available, requiring stringent process control and a thorough understanding of engineered materials and specialty alloys. Meghan McGrath and Boyd Mueller, FASM* Howmet Aerospace, Whitehall, Michigan *Member of ASM International with forging facilities that supply the seamless rings market. Other capabilities include alloy manufacturing, ceramic core production, hot isostatic pressing, special coatings, and machining. In addition, the company’s research center provides applied R&D, equipment builds, and quality control services to each production area. Quality control focuses on chemistry, mechanical and physical testing, metallography, and electron optics. RESEARCH & DEVELOPMENT Within Howmet, R&D activities are centered around developing and improving base materials (wax, ceramics, and metal), investment casting (equiaxed, directionally solidified, single crystal, high gradient, and enhanced equiaxed casting), post-cast processes (thermal, chemical, finishing, and inspections), process simulations (casting, injection, and deformation), data science and analytics, and new product services (concurrent engineering, rapid tools, rapid patterns, and rapid cores). R&D efforts work alongside manufacturing to enable new OEM designs such as the multiwall cooling configurations mentioned above. Equipment builds for plant growth and maintenance are also supported by the research center. Casting furnaces, To increase the amount of cooling while using less air, engine manufacturers have moved from 2D cooling designs, where the air is not parsed between the pressure side (hot gas path impingement) and suction side of the airfoil, to 3D cooling that features multiwall designs (Fig. 1). These more complex cooling schemes allow OEMs to direct air to the exact regions that encounter the highest heat loads without wasting cooling on areas of the blade that do not need it. Modern investment casting facilities at Howmet support the aero engine airfoil, structural, and landbased gas turbine airfoil markets along Fig. 1 — Transition from 2D airfoil designs to multiwall cooling designs enables manufacturers to run turbine engines at higher temperatures and more efficiently with less cooling air.
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