It is often done to create more interest or lightness in a design. A shape, or many shapes are cut into the design going all the way through.
When the openings are small and delicate and numerous it can look like filigree. Filigree however is known for using wire in its work. This openwork technique can be done on the metal itself or worked into the wax model before it is cast. This is also called “pierced through” work.