Thickness effects on profile and surface in micro deep drawing of stainless-steel foils

Micro deep drawing (MDD) enables the precise production of microscale hollow, thin-walled components for aircraft and medical applications. MDD of SUS301 stainless-steel foils with thicknesses of 30–50 μm was investigated under dry and TiO₂ nanolubrication conditions using a fixed tool configuration. A size-effect-based constitutive model was developed to describe the thickness-dependent forming response in MDD. Compared with dry conditions, 2 wt% TiO₂ nanolubrication reduced drawing forces across all thicknesses. Nanolubrication improved microcup morphology by suppressing wrinkling and enhancing dimensional accuracy. EDS analysis revealed a thickness dependence in lubricant behaviour, with uniform nanoparticle distribution at 40 μm and unstable accumulation at 30 and 50 μm. These results elucidate the coupled effects of foil thickness and nanolubrication on MDD performance and provide a quantitative basis for optimising microforming of austenitic stainless steels.