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Indian startup 3D prints rocket engine in 72 hours

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Re: Indian startup 3D prints rocket engine in 72 hours

#141

Post by sobellian »

vasco wrote: post #49
Etheryte wrote: post #26

> The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification. Anyone who's previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to re…

If any system could measure its own signal to noise accurately, it wouldn't have any noise in the first place.

This is a "truthy" statement that sounds right but is, in fact, false. Radio systems have an easily measurable SNR, but the noise cannot be eliminated.

Re: Indian startup 3D prints rocket engine in 72 hours

#142

Post by sandworm101 »

NortySpock wrote: post #127
Etheryte wrote: post #26

> The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification. Anyone who's previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to re…

To steelman the argument, maybe they meant "the monitoring system is good enough at catching defects that if none are reported, the engine will probably pass an all-up hotfire test of the engine". Of course you could do a water or air-pressure leak test on the plumbing pretty easily, and you would likely do that on the first 30 engines... But if you have confidence in your build process, maybe the juice isn't worth t…

>> maybe the juice isn't worth the squeeze

In rockets/aerospace, where the failure of any one of a thousand different parts means instant disintegration, checks are always worth the squeeze. Everyone talks about building rockets on the cheap and accepting a slightly-higher failure rate, but in reality that doesn't work. Even a tiny increase in component fault rates translates to total mission failure once multiplied across thousands of vital parts. The answer isn't to not check but to find ways to more efficiently and more thoroughly check each part. This is only more true if one considers reusable rockets where components will be expected to participate in multiple launches.

Re: Indian startup 3D prints rocket engine in 72 hours

#144

Post by lukan »

rvnx wrote: post #73
raverbashing wrote: post #64

Earlier quoted context omitted.

Well there were probably some early warning signs The problem is that warning sign comes at around 10ms or less before the actual disaster

If it would be a Tesla, just enough time for the auto-pilot to disengage and claim it was the fault of the user.

Is there data, that indicates Tesla did this, or something like this?

Re: Indian startup 3D prints rocket engine in 72 hours

#145

Post by dotnet00 »

skybrian wrote: post #132
Etheryte wrote: post #26

> The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification. Anyone who's previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to re…

I’m curious about why that is. Naively, it seems like printing layer by layer would allow for a lot of inspection. Maybe even photograph each layer as you go? And then test and go back to see what kinds of defects were apparent in the photos.

It's just that it's very easy for deviations from what the sensors see to occur. In traditional 3d printing, this can be stuff like a sensor switch wearing out, maybe physically moving slightly, being temperature sensitive, maybe the frame has changed shape slightly due to heat, moving the sensor a little, maybe something in the microcontroller happened to cause a slight delay in reading the sensor, or looseness developing in the motion system, or something being slightly out of alignment, or some component in the extrusion system experiencing momentarily higher friction and so on.

The layers are really thin, so manually inspecting them would slow down the printing process drastically. Then, ultimately, what even can you do if there's a defect? The layer has been laid already. If material is missing somewhere, you could have the machine go back and add it, but if there's excess material somewhere, or it's in a form that the machine can't fix, there's not a lot to be done, particularly in applications like rocketry, where your structural strength tolerance are very tight.

Re: Indian startup 3D prints rocket engine in 72 hours

#146

Post by metal_am »

skybrian wrote: post #132
Etheryte wrote: post #26

> The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification. Anyone who's previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to re…

I’m curious about why that is. Naively, it seems like printing layer by layer would allow for a lot of inspection. Maybe even photograph each layer as you go? And then test and go back to see what kinds of defects were apparent in the photos.

Peregrine from Oak Ridge National Lab does exactly this. Lots of other research papers about it too.

Re: Indian startup 3D prints rocket engine in 72 hours

#147

Post by Ruthalas »

skybrian wrote: post #132
Etheryte wrote: post #26

> The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification. Anyone who's previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to re…

I’m curious about why that is. Naively, it seems like printing layer by layer would allow for a lot of inspection. Maybe even photograph each layer as you go? And then test and go back to see what kinds of defects were apparent in the photos.

You are correct, and with the current metal AM techniques (DED, SLM), you can also take thermal imaging of the melt pool throughout. From this you can a pretty accurate picture of the weld quality across the whole volume.

I'm not sure that's sufficient to eschew any other non destructive testing, but it is great information.

Re: Indian startup 3D prints rocket engine in 72 hours

#148

Post by metal_am »

dotnet00 wrote: post #145
skybrian wrote: post #132

Earlier quoted context omitted.

I’m curious about why that is. Naively, it seems like printing layer by layer would allow for a lot of inspection. Maybe even photograph each layer as you go? And then test and go back to see what kinds of defects were apparent in the photos.

It's just that it's very easy for deviations from what the sensors see to occur. In traditional 3d printing, this can be stuff like a sensor switch wearing out, maybe physically moving slightly, being temperature sensitive, maybe the frame has changed shape slightly due to heat, moving the sensor a little, maybe something in the microcontroller happened to cause a slight delay in reading the sensor, or looseness deve…

I know for certain that defects in the powder layer can be fixed in binder jet by redoing the recoater. There has been talk in the research world about being able to fix errors in L-PBF but I’m not sure they’ve gone past the research stage. The big point is that you can know a part might be out of whatever your acceptance criteria might be.

Re: Indian startup 3D prints rocket engine in 72 hours

#149

Post by giantrobot »

sandworm101 wrote: post #142
NortySpock wrote: post #127

Earlier quoted context omitted.

To steelman the argument, maybe they meant "the monitoring system is good enough at catching defects that if none are reported, the engine will probably pass an all-up hotfire test of the engine". Of course you could do a water or air-pressure leak test on the plumbing pretty easily, and you would likely do that on the first 30 engines... But if you have confidence in your build process, maybe the juice isn't worth t…

>> maybe the juice isn't worth the squeeze In rockets/aerospace, where the failure of any one of a thousand different parts means instant disintegration, checks are always worth the squeeze. Everyone talks about building rockets on the cheap and accepting a slightly-higher failure rate, but in reality that doesn't work. Even a tiny increase in component fault rates translates to total mission failure once multiplied…

> In rockets/aerospace, where the failure of any one of a thousand different parts means instant disintegration

To make matters worse the failure modes don't only affect the launch vehicle itself. A failure of a rocket likely means a total loss of the payload. It also runs the risk of damage/loss of the launch pad, support structures, and hapless down range victims.

Rockets contain a significant amount of stored chemical energy, enough to get the payload mass into a stable orbit of the Earth. If you release all of that energy at once as an explosion it will cause a significant amount of damage. Rockets aren't something to goof around with and make assumptions about safety.

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