An enclosure body does three jobs at once: it isolates the inside from the environment, carries away the heat the electronics generate, and provides electromagnetic shielding through its conductive body. Aluminium die casting combines all three in a single part — no separate shield plate, no separate heat sink.
Gasket grooves, cover faces and cable gland seats are solved directly in the die. Heat sink fins are cast as part of the body; fin pitch and height follow the airflow of the environment the part will work in.
Bodies that require sealing are pressure tested after machining; the surface treatment is chosen according to the corrosion conditions of the application.