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Rolls-Royce’s single-crystal turbine blade casting foundry

theengineer.co.uk

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Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#41

Post by caf »

orf wrote: post #13

I had the chance recently to see the Mayor of the City of London's (the strange city-within-a-city bit of London) two Rolls Royce's they keep for formal occasions up close. They are super rare (only ~400 ever made), worth a whole lot of money and looked amazing . I'm not a car person but you can't help but feel a shiver when you see a car like that. The engines where the same as the ones they used in the Spitfire fig…

That's also the car the Governor-General of Australia uses on formal occasions.

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#42

Post by caf »

Gravityloss wrote: post #32

And to think all this technology is used mostly for cheap holiday flights.

Well, without that mass market of holidaymakers we wouldn't be able to afford to use the technology for more highbrow purposes like attending scientific conferences.

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#43

Post by pcl »

phasetransition wrote: post #33
filereaper wrote: post #9

On this topic, I'd like to ask how 3D printed parts fair in the new engines being built. [1] I'd love to hear about this from a Metallurgical Engineer or a Material Science Expert. [1] http://qz.com/667477/ge-fires-up-worlds-largest-commercial-j...

My graduate research was on a corner of the class of ceramic materials that are used as coatings on top of this type of turbine blades. Anything specifically you would like to know? Generally, single crystal blades are designed for their resistance to creep at high temperatures. If your predominate creep mechanism is sliding at grain boundaries in a polycrystalline material, you can impart creep resistance by removin…

What sorts of considerations are important for the ceramic coating? I'd assume that the coating is not under the same types of stress as the alloy core, and so thermal properties would be more important. Is that true, or is load as much of a factor there too?

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#44

Post by spitfire »

orf wrote: post #13

I had the chance recently to see the Mayor of the City of London's (the strange city-within-a-city bit of London) two Rolls Royce's they keep for formal occasions up close. They are super rare (only ~400 ever made), worth a whole lot of money and looked amazing . I'm not a car person but you can't help but feel a shiver when you see a car like that. The engines where the same as the ones they used in the Spitfire fig…

6.75 Litre V8. or as they said "Six and three quarters".

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#45

Post by megablast »

orf wrote: post #13

I had the chance recently to see the Mayor of the City of London's (the strange city-within-a-city bit of London) two Rolls Royce's they keep for formal occasions up close. They are super rare (only ~400 ever made), worth a whole lot of money and looked amazing . I'm not a car person but you can't help but feel a shiver when you see a car like that. The engines where the same as the ones they used in the Spitfire fig…

Just looks like another car to me, but I am not a car person.

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#46

Post by emmelaich »

Sophistifunk wrote: post #37
orf wrote: post #20

Earlier quoted context omitted.

Ahh, shame, you're right. They where 27 litre as well! That would be a bit extreme. Seems someone was silly enough to put it in a car though: https://www.youtube.com/watch?v=u43pWEwI6xY

There are more of these projects than you might think. Final Objective (a 55 Chev) is the best, IMO: http://www.australiastoughestcars.com.au/news/video-merlin-v...

This guy "Lucky Keizer" made a 5l v-twin motorbike from a Merlin engine.

http://www.abc.net.au/local/photos/2015/08/19/4296075.htm

I saw it live once, unfortunately he couldn't start it. I suspect it's a frequent problem.

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#47

Post by bobsil1 »

hcrisp wrote: post #12
gertlex wrote: post #5

This was a super fun read, and it felt nice to take the time to carefully read it to understand the very complex processes it was describing. That said, can someone explain how the pigtail accomplishes the following?: > "The crystals grow in a straight line in the direction that the mould is being withdrawn, but because of the pigtail’s twisted shape, all but the fastest-growing crystals are eliminated."

By the principle of elimination by bottleneck. As the crystals grow into the pigtail, the lagging crystals hit the already-formed leading ones or the mold surface, leaving a primary, single crystal grain to exit the pigtail and grow across the blade proper. This would be almost impossible to happen without the pigtail because multiple crystal grains would grow in parallel across the blade.

How does this compare with pulling a silicon boule? Any chip people care to chime in?

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#48

Post by FabHK »

Animats wrote: post #21
hcrisp wrote: post #12

Earlier quoted context omitted.

By the principle of elimination by bottleneck. As the crystals grow into the pigtail, the lagging crystals hit the already-formed leading ones or the mold surface, leaving a primary, single crystal grain to exit the pigtail and grow across the blade proper. This would be almost impossible to happen without the pigtail because multiple crystal grains would grow in parallel across the blade.

Here's a technical explanation.[1] But here's an example of triggering crystal formation in a supersaturated solution.[2] Classic high school chemistry experiment. Dropping a solid crystal into the supersaturated solution causes the whole liquid to turn into a solid in seconds. That's the basis of single-crystal casting. The solidification process relies on operating very close to the melting point of the material. T…

Where's [2]? Thanks!

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#49

Post by ubernostrum »

byebyetech wrote: post #8

This is the best documentary on how RR makes the jet engine and the blades. 1 hour long but once you click it, it would be hard to stop! https://youtu.be/VfomloUg2Gw

Another favorite aviation-related one, though more pop-sci-oriented, is this look at a 747 going through a D ("heavy maintenance") check that basically takes most of the plane apart and puts it back together, covering all the bits and how they need to work:

https://www.youtube.com/watch?v=x_yHtfGH0nI

Re: Rolls-Royce’s single-crystal turbine blade casting foundry

#50

Post by ubernostrum »

sspyder wrote: post #6

Not to take away from the engineering marvel that these parts and process represent, but the timing of this article is interesting - seems PR related. I recently read about problems ANA faced with Rolls Royce engines, specifically the turbine blades failing. There have been at least 3 incidents of engine failure, flights have been cancelled an all 787 engines have to be retrofitted with new blades. http://www.reuters…

the timing of this article is interesting

Earlier today a story about China buying the AN-225 was on the front page and lots of people were confused about why they needed to buy the full toolchain for manufacturing it, instead of just buying one plane and reverse-engineering how to build it.

Several people then pointed out the difficulty of manufacturing modern engine components, particularly the blades, and it was kind of inevitable an article about that would follow soon after.

Also, ANA's 787s are a bit of a weird case in that ANA puts far more cycles on those engines than a typical operator. Most 787 operators use them for long-haul flights, 8-12 hours airborne at a time and only one or two flights per 24-hour period. ANA, on the other hand, flies 787s on much shorter domestic routes, meaning more cycles of spin-up/shut-down. Given that ANA was the first operator and puts way more stress on the engine than anyone else, it's unsurprising that they would see accelerated wear.

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