Abstract: A metal sheet is pierced, pressed and drawn to provide a raised cylindrical section having an axis and which section is partly closed by an annular flange. The flange is bent inwardly to enlarge the cylindrical opening by orbiting a tool in engagement with the flange about the axis and rolling the tool along the flange about a second axis offset from the cylindrical axis to enable enlargement and thinning of the flange. Subsequently, a peripherally screw-threaded cylindrical roller of a diameter less than the diameter of the flange is continuously rolled about the flange in orbital relationship with flange cylinder axis until the surface is deformed into a complementary screw configuration.