Modelling and Validation of Microstructure Replication on Aluminum Foils from Laser-Patterned Stamps

Aluminum foils are commonly used in food and pharmaceutical packaging due to their outstand-ing combination of malleability, low cost, oxygen barrier and light reflectivity. Extra functionalities, like hydrophobicity or structural coloration, can be added to them by engineering topographical sur-faces microstructures. In this work, cold embossing method is used to replicate microstructures from pre-structured stamps onto aluminum foils. The Direct Laser Interference Patterning (DLIP) method is used to structure periodic line-like textures on stainless steel plates. The produced stamps are em-ployed to imprint the Al foils under different controlled pressures. A good transfer of the microtex-tures to the Al based material was observed, with a 6-40% relative difference in the structure depths between master and replica depending on pressure and aspect ratio of the structures on the steel mold. Although a complete replication of the stamp textures is not obtained due to incomplete stamp cavities filling and elastic recovery, the achieved structural coloring demonstrates a uniform micro -texture on the foils. A model based on the finite element method is developed and validated by comparing the simulation results with the microstructured aluminum foils, yielding relative differ-ences in the simulated and experimental structures depths below 20%.

Automated summary

Aluminum foils are widely used in food and pharmaceutical packaging due to their malleability, low cost, oxygen barrier, and light reflectivity. In this study, a cold embossing method is used to transfer microstructures from pre-structured stamps onto aluminum foils. The resulting foils demonstrate a uniform micro-texture, although the replication of stamp textures is not complete. Simulation results show good agreement with experimental data, with relative differences in structure depths below 20%.