Lower-cost, high-performance heat-resistant alloys
Metal alloys, or composite materials consisting of two or more metal elements, are commonly used both in the processing of machining tools as well as in finished products given their strength and heat resistance. The ‘New tools and processes for improving machining of heat resistant alloys used in aerospace applications’ (Macherena) project was initiated to develop new materials, machining tools and processes for the aircraft manufacturing industry resulting in lower production costs and longer tool and part lifetimes. The researchers studied three types of heat-resistant composite materials: iron-nickel (Fe-Ni) alloys, Ni alloys and gamma phase (very high temperature resistant) titanium-aluminide (Ti-Al) intermetallic alloys. They investigated drilling, milling and turning processes. Drilling refers to creating a round hole or enlarging an existing one whereas milling and turning involve cutting away unwanted material in the form of small chips to create desired features. The researchers first developed novel nano-composite coatings employing physical vapour deposition (PVD) techniques to meet hardness and low-friction requirements. They applied the coatings to standard and new machining tools, optimising the best coating geometries to avoid the chipping failure that leads to unreliable and unpredictable machining and causes severe damage in very expensive components. In addition, novel high pressure cooling machining processes were applied to increase machining speed and tool lifetime. In particular, the lifetime of Inconel drills was increased by 50 % with this process. In summary, the Macherena project developed new nano-composite coating materials, innovative tool geometries and advanced machine processing using high pressure cooling for heat-resistant metal composites used by the aerospace industry. The outcomes resulted in increased machine productivity, longer tool lifetime and enhanced finishing quality with decreased production costs. Taken together, the Macherena project outcomes should provide a competitive edge to the European aerospace industry, enabling more cost-effective manufacture of high-performance aircraft parts.
