There are many ways.

Firstly, the whole blank is processed into two hemispheres and welded together to complete the appearance; Then milling the surrounding round holes; Finally, weld the flange and polish it.

Secondly, the blank can be made by casting and then finished.

Specifically, it is precision casting by lost wax method. First, make a wax model. The shape of the picture needs to be made into multiple sets of molds, and wax parts can be produced by molds. Then the wax parts are put together (the same shape as the product), coated with sodium silicate and quartz sand, sintered into a shell (the wax inside is gone), and finally poured to complete the blank.

Of course, urea core can also be used. Please refer to the production process of the valve for details.