Differents Materials and Their Use

Cost is a big factor. Aluminum does cost alot to manufacture over others.

The cost of Aluminum is negligible when compared to machine and design time. It machines faster with less wear on your tools, which lowers those costs.

Engineering begins with listing the requirements that the part must meet.

Then identifying potential materials and fabrication processes that meet those requirements.

Then determining cost benefit tradeoffs between competing materials and processes to fabricate the desired part.

anything less is just guessing, and in the States would be likely rewarded with a big fat lawsuit.

For a gear, The material chosen depends on load;

The material will be chosen for its ability to meet mechanical properties, and whether or not it is amenable to any needed surface treatments (carburizing, flame hardening etc.) (Typically Gears are made from lower carbon steels to give good toughness, while a case hardness is put on the surface of the teeth to minimize wear. however, for many applications higher carbon containing heat treated alloy steels or cast steels are used) The material choice will also be affected by need to meet environmental and service conditions expected for its application.

The method of manufacture will be chosen depending on the dimensions, features, and number of parts required.

I have described all of this in words, to do engineering, each of these would be described and solved mathematically.

milo

do right and fear no man, don't write and fear no woman

We all agree with a key issue: cost.

Ultimately, what you have is how much you can ask people to pay for something. Then, with this value in mind, you will design your device to be produced within this value less the minimum attractivity margin of your business.

Depending on your cost and your application, you choose the material that would support your load AND environmental conditions AND with a manufacture process that will allow you to run within budget.

If you can solve this equation, you will manufacture it. If not, you will try to do the same thing in a cheaper way, or you will put more money in marketing to make people pay more for the cheap device you've built.

Yes, it seems horrable, but I'm affraid the golden years of the mechanics are gone.