Clearance

The vertical walls of a drawn part become thicker towards the open side. The tangential compressive stresses cause the sheet metal to become thicker than the sheet thickness s₀. This is limited by the clearance u_Z (distance between punch and drawing ring). If the sheet metal completely fills the clearance , there is a superimposed stretching of the sheet metal.2519269

For the draw ratio β₀ see Round Drawn Parts.

The drawing force reaches its smallest value at the largest permissible clearance u_{Z max}.

If the internal dimensions of the workpiece are given, the punch diameter is fixed and the drawing die becomes 2 x the clearance larger. If the outer diameter of the drawn part is dimensioned, the punch diameter is selected so that it is equal to the drawing die - 2 x clearance.25

With a small draw ratio β_0, a small die radius r_M and the gap width u_Z < s₀ can be selected. The frame is then stretched during deep drawing. However, the floor can tear off due to the increasing drawing force.25