Abstract: A new criterion for determination of the limit drawing ratio of the deep-drawing is proposed, in accordance with deformation of the collar flange and deformation of the billet near the radius of punch. This criterion can be used to study the quantative influence of the properties of working materials and the technological parameters on the limit drawing ratio (mk). Moreover, the formula of the limit drawing ratio has been derived for the deep-drawing of the cylindrical cup with flat-nosed punch, on the basis of the analysis of deformation of the billet near the radius of punch. In terms of the calculated results, the optimum values of technological parameters during the deep-drawing are calculated. The experimental results show that the calculated value (Mk) of the limit drawing ratio is credible and the suitability of this criterion proposed is very well.

Key words: Criterion, Deep-drawing, Limit drawing ratio, Sheet metal