Control of
the metal flow in the die cavity is a key
factor in producing sound die castings. Metal must flow rapidly and uniformly into the die,
minimizing sharp direction changes, turbulence, and entrapped air.
A key feature in die design is the
positioning of the runners and gates -- the passages that feed
molten metal into the die cavity.
Well-designed
gates are positioned to permit rapid flow into the thicker
sections of the die cavity and to provide smooth flow paths
that minimize turbulence in the molten metal.
The
placement of the gates will also impact the surface finish of the
final part. When gates are trimmed off, the trim operation can leave
surface roughness. For the best surface finish, gates should be
placed on low visibility surfaces.
