Casting tool and method for producing a piston for an internal combustion engine

A method for producing a piston, comprising:

• introducing a casting melt into a casting head of a casting tool via an inlet;
• casting the casting melt, wherein casting the casting melt includes at least one of:
• forming the casting melt into a ring-shaped sealing rib via a ring-shaped groove of the casting tool that extends around a feeder of a thermally insulating material in the casting head at a radial distance therefrom, such that upon solidification of the casting melt an inner rib flank of the sealing rib rests with a sealing effect against an inner groove flank of the groove, wherein forming the casting melt into the ring-shaped sealing rib includes contacting the casting melt with the inner groove flank having a slope angle of 10° to 15° relative to a perpendicular to a surface of the casting head to facilitate sealing the casting melt along the inner rib flank;
• and
• forming the casting melt to provide a ring-shaped sealing groove via a ring-shaped collar of the casting tool that extends around the feeder in the casting head at a radial distance therefrom, such that upon solidification of the casting melt an outer groove flank of the sealing groove rests with a sealing effect against an outer collar flank of the collar, wherein forming the casting melt into the ring-shaped sealing groove includes contacting the casting melt with the outer collar flank having a slope angle of 10° to 15° relative to a perpendicular to a surface of the casting head to facilitate sealing the casting melt along the outer groove flank;
• inserting at least one porous insert into a casting mold of the casting tool, and infiltrating the at least one porous insert with the casting melt via exerting a pressure on the casting melt, wherein infiltrating the at least one porous insert includes providing a negative pressure via suction lines leading to the at least one porous insert to facilitate infiltration with the casting melt;
• and
• guiding the feeder in the casting head via a sleeve coupled to the casting head, the sleeve extending through the casting head from an interior of the casting mold outwards beyond the casting head, and wherein a pressurized gas line is coupled to the sleeve in a pressure tight manner for pressurizing the casting melt.