After parts are ejected from a die cast machine, the gates (arrow #1) and overflows (arrow #3 & #4) need to be trimmed manually or by the use of a trim die.
A trim die is used when 1) the gates are very strong and difficult to remove manually; or 2) when the gates are located near the center of the part, such that it may damage the part while breaking the gates manually, as marked by arrows #5 & #6.
Burrs on ejector marks (flip side of arrow #2) or elsewhere need to be deburred.
After trimming overflows and gates, there might be some materials on the edges that need to be polished away. See arrow #4.