How propellers are manufactured?

Propeller are normally made of 

• Magnesium bronze
• Nickel Aluminium bronze

It is casted centrifugally. It is done to have flawless cast metal, with no blowholes. The metal density is made optimum as it is subjected to extreme stress as such when casting is done centrifugally, the first metal solidifies at the tip ensuring the required metal density.

Small propeller - Brass

Shaft - Forged Steel

Propeller tip clearance:-0.48-0.02 x number of blade (mm)

Steam tube

Liner- Nickle chromium-molybdenum steel.

Seal - Perbunan- S Vitae plain rubber