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View Full Version : So How Do they "make" props anyway?



Craig
02-15-2004, 09:51 AM
Anybody ever wonder about this.

I'm sure quite a few here know the process, but I just read this in an old Quicksilver book I've had for probably 20 years. Maybe the process is old, but I thought I'd pop it up. I found it interesting:

How are propellers manufactured?

In the unique investment casting (lost wax) process, special wax is pressure-injected into a polished propeller die, thus insuring high dimensional accuracy in every detail.
The warm, delicate wax replica of the propeller is taken from the mold and cooled. Wax patterns are collected in a temperature and humidity controlled room to maintain dimensional stability.
Next, the wax pattern is dipped into a slurry that contains binder and dry refractory particles. This (dipping and "stuccoing") is repeated several times until the ceramic shell around the wax pattern is the desired thickness. To remove the wax from the inside of the ceramic shell, the shells are placed in a steam autoclave. This unit melts out the wax leaving a precisely accurate ceramic shell.
The shell is then heated to 1100 degreesF (611 degrees C) to make a completely inert ceramic mold. During this time, ingots of stainless steel are melted in an electric furnace. Prior to pouring the molten metal, a catalyst is added to assure a fine stainless steel grain structure.
White hot ceramic molds next are filled with molten metal. When they cool, the ceramic shell surrounding the propeller is knocked off. Finally, the propellers are sandblasted to thoroughly clean them.

(from "Everything You Need To Know About Propellers" Third Edition)

Pretty Cool, huh?

You prop experts, feel free to chime in if the process has been greatly altered since this old book was put together.

Propeller Riddle:

If "Implode" is the opposite of "Explode", and a jet drive's propulsion unit is called an "Impeller", why aren't Propellers called "Expellers"???

POSSIBLE ANSWER: because then you couldn't just call them "Props" for short!! They'd be nicknamed "Exp's" which doesn't sound as cool and is hard to pronounce!