Apparatus for flaskless sand casting

A relatively hard sand cake, containing a metal casting cavity, is formed in a flask comprising cope and drag frame sections by filling and compacting sand in the drag against the drag half of a cavity-forming pattern, then arranging the drag with the cavity opening upwards, applying the cope upon the drag and filling and compacting sand in the cope against the cope half of the cavity-forming pattern. The sand-filled cope is lifted from the drag for removal of the pattern and is re-applied to form the casting cavity in the sand cake. Next, selected wall corner joints of both the cope and the drag frames are separated and opened to laterally expand the walls of the frames away from the sand cake surfaces. This releases the sand cake from the cope and drag so that it may be removed from the flask for later casting molten metal in its casting cavity. At least two of the corners of each of the cope and drag frames include a separate corner piece against which the adjacent ends of the frame walls are abutted. A releasable fastening mechanism secures the corner pieces to their adjacent frame walls and may be selectively operated to separate the corner pieces from their adjacent walls for opening the wall corner joints.