A cassette cartridge comprising a first casing shell (6) having a recess (11) formed proximate a side wall portion thereof and a second casing shell (7) matingly fitting with the first casing shell (6). The second casing shell (7) has a projection (10) formed at a location corresponding to the recess formed in the first casing shell such that a dimension of a surface of the projection (10) contacting a bottom of the recess (11) is less than a corresponding dimension of the bottom of the recess (11) so that on joining the two shells welding burrs may be contained. <IMAGE>
