The maximum force (Fb) of the specimen during the drawing process is the tensile strength (σb), expressed in terms of the stress (σ) of the original cross-sectional area (So) N / mm2 (MPa). It represents the maximum capacity of metal materials to resist damage under tension. The formula is: where: Fb - the maximum force that the specimen is pulled off, N (Newton); So - the original cross-sectional area of the specimen, mm2