In the relentless pursuit of lighter, stronger, and more efficient materials, industries like aerospace and automotive are increasingly turning to aluminium/carbon fibre reinforced polymer (Al/CFRP) stacks. These composite materials combine the best of both worlds: the high strength-to-weight ratio of carbon fibre with the ductility and impact resistance of aluminium. However, as Balázs Markó from the Budapest University of Technology and Economics points out, “While the benefits are clear, the challenges in machining these materials, particularly at the interlayer regions, have been significant.”
The primary issue lies in the formation of interlayer burrs during mechanical machining. These burrs can compromise the structural integrity and aesthetic quality of the final product, leading to increased production costs and potential safety concerns. To tackle this problem, Markó and his team have developed an innovative hole-making technology that minimises machining-induced interlayer burr formation.
The novel technology integrates helical and spiral interpolation strategies to reduce axial force at the interlayer interfaces. “By carefully controlling the machining process, we can significantly reduce the formation of burrs,” explains Markó. The team validated the efficiency of their technology through a series of machining experiments, employing a Central Composite Inscribed (CCI) experimental design. The experiments were performed on a three-axis CNC milling centre, with burr measurements obtained using a Keyence VR-5000 3D profilometer. Maximum burr heights were recorded along the hole contours at one-degree intervals.
The results were promising. The team observed a significant reduction (28%) in interlayer burr formation in unidirectional carbon fibre-reinforced polymer (UD-CFRP) plates when utilising the proposed technique. This improvement could have substantial commercial impacts, particularly in the energy sector where lightweight, high-strength materials are in high demand for applications such as wind turbine blades and automotive components.
As the world continues to push the boundaries of material science, research like this is crucial. It not only addresses current challenges but also paves the way for future developments. “Our findings suggest that the developed method is promising to improve machining quality in Al/CFRP stacks,” says Markó. “This merits further investigation and development, and we are excited to see where this research will lead us.”
The study was recently published in the journal ‘Composites Part C: Open Access’, which translates to ‘Composites Part C: Open Access’ in English. As industries continue to evolve, so too will the materials they rely on. And with researchers like Markó at the helm, the future of material science looks brighter than ever.