Abstract: The method is provided for producing a first primary roll (8) having a predetermined lateral surface defined by a diameter D.sub.f, or for determining an amount of material available on a primary roll. The primary roll is made of material wound around a spindle (6). The material is used to produce smaller secondary rolls (12) of material. The method for producing the primary roll of material comprises steps of (a) calculating portion S.sub.f of the lateral surface, which is covered by the spindle; (b) calculating a portion S.sub.i of the lateral surface, which represents material needed to produce the smaller secondary rolls of material; (c) calculating a compression factor K1 which is derived from a compression rate K of a previous second primary roll used to produce previous secondary rolls with respect to the previous secondary rolls; (d) calculating D.sub.f where: D.sub.f =(4(S.sub.f +(S.sub.

Abstract: The method is for producing a first primary roll having a predetermined lateral surface defined by a diameter D.sub.f. The primary roll is made of material wound around a spindle. The material is used to produce smaller secondary rolls of material. The method comprises steps of (a) calculating a portion S.sub.f of the lateral surface, which is covered by the spindle; (b) calculating a portion S.sub.i of the lateral surface, Which represents material needed to produce the smaller secondary rolls of material; (c) calculating a compression factor K1 which is derived from a compression rate K of a previous second primary roll used to produce previous secondary rolls with respect to the previous secondary rolls; (d) calculating D.sub.f where: ##EQU1## (e) winding up material around the spindle to produce the first primary roll until a diameter of the first primary roll reaches said diameter D.sub.f ; whereby loss of material is reduced by taking into account compression factor K1 which varies with respect to time.