The invention relates to a casting tool for producing workpieces from light metal alloys. The system includes a positioning element, a core part, a first mold part structured to carry the positioning element and be movable toward the core part, and a core part support structured to support the core part. The system also includes at least one stop structured to limit movement of the front mold part toward the core part and to allow the positioning element to be introduced into the core part, whereby the positioning element holds the core part in a predetermined position for casting.