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Comment by jecel | Hacker News Reader

Tesla invented this because he wasn't happy that cavitation was reducing the life of bladed turbines.

A plastics injection molding mechanical designer in China told me rotational blades are the hands down most irritating thing to try to injection mold because conventional tolerance factors that are very well suited to the production of most other products will often result in imbalance, noise, vibration, wear and failure in rapidly rotating bodies.

I've seen a five axis mill that is used to cut turbine blades (in Poland, through an industry contact of mine), it was an absolute work of art and I totally believe the injection mold designer. Everything was compensated for, including tool wear and heat injection. the whole thing was cut in one run without any tool changes or re-registering. One set of tools for one blade.

I used to work at a plant like this, we were acquired by Siemens. The machining process itself is less critical than the balancing and even the welding of these components, which is highly engineered and controlled.

I can imagine. Manufacturing tolerances will have some minor effect on balance and efficiency, failure of a weld or large imbalance or resonance would be fatal. Even so, the machining process itself was quite impressive to someone who is used to 'regular' CNC machining without working to such close tolerances. The movement of the cutter was very interesting too, hypnotizing if you will :) I forgot what the material was, these blades were for aircraft turbines.

What kind of turbine blades did you work on? Gas turbines for stationary applications or for aircraft or something else? Do you remember what material they were made out of?

That is the kind of process engineering and fabricating that is fascinating to me.

It is. The company that built the system makes very nice stuff.

This is the Chinese parent company with subsidiary in Germany:

https://www.inovance.eu/industries/cnc-machine-tools

And this is the notice about them acquiring Powerautomation, the German company that designed and manufactured those controllers:

https://www.inovance.eu/news/details/inovance-technology-eur...

PA was a fantastic company but like many such specialist producers they didn't have a clear succession path laid out so they eventually got sold.

I’m similarly interested. Does anyone know of an introductory book on modern production technology? It somehow seems to be an impenetrable topic to me without actually doing a major in some kind of engineering.

This would be a great start but it is a pretty large book:

https://books.industrialpress.com/9780831136369/the-cnc-hand...

Also, the materials science and engineering handbook. It's floating around on the web in PDF form if you just want to skim it but if you really need it you should probably buy a copy (warning: huge book):

https://www.amazon.com/Materials-Science-Engineering-Handboo...

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