The present invention relates to an apparatus for forming air-laid absorbent cores (13,14), comprising a first and second mat-forming wheel (1,2), means for transferring a core element on the first mat-forming wheel onto a core element on the second mat-forming wheel while the latter core element still is maintained in its mould, at least the air-laying means associated with the second mat-forming wheel comprises means for supplying a mixture of air-entrained fibrous material and discrete particles. According to the invention the apparatus comprise means for applying a protective layer to the bottom of each mould (4) of the second mat-forming wheel (2), which protective layer has the function of protecting the mould from discrete particles during air-laying of a mixture of air-entrained fibrous material and discrete particles, means for applying a web (15) of casing material on the peripheral surface of the first mat-forming wheel (1), whereby suction means (6) inside the first mat-forming wheel will draw the material in the web (15) to abutment against the bottom of a mould (3) passing said suction means, means for guiding said web of casing material onto the periphery of the second mat-forming wheel after having passed the nip between the first and second mat-forming wheel (1,2), and means for changing the synchronization of the mat-forming wheels in order to control the time at which the leading edge of a mould (3,4) on one of the mat-forming wheels passes the nip in relation to when the leading edge of a mould on the other mat-forming wheel passes the nip. The invention also relates to a method of producing cores with different sizes without change of moulds.La présente invention concerne un appareil pour former des âmes absorbantes obtenues par formation pneumatique (13,14), qui comprend des première et seconde roues de formation de mat (1,2), des moyens pour transférer un élément dâme sur la première roue de formation de mat à un élément dâme sur la seconde ro
