Close-up of the manhole cover and cast iron grating foundry

Manhole covers and drainage gratings on the road seem very familiar to each of us. But how are these products produced?
Please watch the short clips close-up of the casting process of manhole covers, drainage gratings and cast iron gratings at the Viet A foundry.
Video link at: https://vietaco.vn/can-canh-xuong-duc-nap-ho-ga-song-chan-rac-gang-944.html