The maximum drawing loads of aluminium of commercial purity have been measured during deep drawing. Materials with different impurity levels and plastic anisotropy were investigated. The maximum load was observed to decrease with increasing values of the normal anisotropy ratio r when the flow stress in uniaxial tension was taken into consideration to an extent which was in a reasonable agreement with Hill's theory for orthogonal anisotropy. The effect of the r value on the flow stress-strain conditions which exist under plane strain in the cup wall is difficult to measure, but the strains at the potential failure site, which are affected both by cup-wall strength and drawing load, diminish with increasing r value. The difference inflow stress between uniaxial and balanced biaxial tension cannot be explained by Hill's anisotropic modification to plasticity theory.
