Application of CaCO₃ as Anti-Friction Lubricant Additive to Improve Robustness in Sheet Metal Forming of High-Strength Aluminum

High-strength aluminum is a good candidate for use in light-weighting applications, but forming it is difficult due to its low formability. Elevated temperatures are therefore necessary to improve formability, but this reduces lubricant performance. The use of calcium carbonate (CaCO₃) as a lubricant additive in warm- and hot-forming of high-strength aluminum is evaluated by strip-drawing tests at room temperature, 225°C and 425°C. Further, the influence of tool surface roughness on the performance of the particles in reducing friction is evaluated. Lastly, the particle-additivated oil is compared to fully formulated, commercially available warm- and hot forming oils. The results show that CaCO₃ particles are suitable for improving tribo-systems in warm- and hot-forming of aluminum, and that they can robustify processes where preparation and maintenance of tool surfaces is difficult as the tribo-system is less sensitive to the tool surface. The performance of the particle-additivated oil was similar to the commercial lubricants at room temperature and 225°C, but was worse at 425°C. However, due to the low cost and effort necessary to prepare the particle-additivated oil, it is a promising alternative to existing lubricant additives.