Sprue Lock - In injection
molding, a portion of the plastic composition which
is held in the cold slug well by an undercut; used
to pull the sprue out of the bushing as the mold is
opened. The sprue lock itself is pushed out of the
mold by an ejector pin. When the undercut occurs on
the cavity block retainer plate, this pin is called
the Sprue Ejector Pin.
