TUNELADORAS - How do China's slurry Tunnel Boring Machines come into their beings?

If scenes in the Wondering Earth ever turn real, we will build up mega underground cities and seek to exist only beneath the surface of the earth. Slurry Tunnel Boring Machine is not a part of our day to day talks but is a kind of indispensable machinery and an advanced technology used to construct tunnels.
China's very own laboratory platform manufactures the main bearing of TBMs. A close-up to the manufacturing end of TBM answers questions from both science junkies and curious folks alike.