The invention relates to a separation disc and a milk separator comprising a rotor, which separation disc together with other separation discs forms a stack of separation discs rotatable together with the rotor. The separation disc comprises a truncated substantially conical portion and an annular flange element connected to the conical portion at the smallest radius and extends therefrom radially inwards substantially perpendicular to the axis of rotation. The flange element has a radial extent corresponding to at least 10% of the radial extent of the conical portion. The inner radial edge of the flange element includes recesses distributed along the edge and adapted to protrusions on a column connected to the rotor, extending coaxially through the separation discs. The recesses are substantially filled by the protrusions. The radial extent of the recesses corresponds to at least 20% of the radial extent of the flange element.