How to make a large propeller
Large propellers are all cast, and the propeller mold is designed according to the 3D file or model value table of the propeller. The mold is generally a box-type sand mold, and the parting surface is the page of the blade. The page is in the lower sand box, and the leaf is back in the upper sand box. Soaking in sea water for decades will not decompose. The main material of the alloy is 80% copper, 10% aluminum and nickel, and 10% other metal materials. The tensile strength is 650 N per square millimeter, which means that it can withstand 66,000 meters of water pressure, which is sufficient for the propeller. Of course, this is the strength that can be achieved under the normal proportion of the alloy, so each time it must be tested in the laboratory before casting. Classification societies must issue inspection reports for materials, and each piece of metal has a heat number and material physical and chemical performance report.
