Turbomolecular Madness - A Nerve-Wracking Experience
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- Опубліковано 26 вер 2024
- In today's video, I'll be evacuating my vacuum chamber using my massive Pfeiffer TPH2101. The TPH2101 is a turbomolecular pump with a pumping speed of 1400 L/s. To do this, I had to fabricate a reducing flange first. The pumping speed is simply impressive.
Wissel Vakuum: wissel-vakuum.de/
Join my Patreon and support my projects! Your contribution means the world to me and helps bring my ideas to life. I truly appreciate your support! / advancedtinkering
props to the owner of mr vacuum for allowing you to do that.
Yes, definitely!
😂
For real. Coolest thing I've ever seen.
Allowing? The correct sentence would more be; "props to the owner of mr vacuum for giving you the pump and controller to play with".
@@dtiydrbro ur not smart
The scary sounds are normal with mag lev bearing pumps. It is due to the pump passing through mechanical resonance bands as the pump controller tries to actively cancel destructive resonances in the lower audio range. ❤
Aha, so that is the reason they have a cost a of a small countrys GDP.
It's important to go under or over the resonance bands...
My guy, those welds are impressive!. seriously, most people wouldn't even be able to run a TIG without going through a whole box of tungsten tips first try. meanwhile you're over here stacking dimes.
Also, ramp up vibrations are spooky. I used to have to use a large bench grinder at work, had a 10 inch aluminum oxide wheel on that thing. When you turn it on, the thing near shakes every bolt out between 40 and 60% speed but runs smooth as butter otherwise.
Thank you a lot! But to be fair, the pulse mode of the welder makes a huge different. Without it my welds did look worse.
@@AdvancedTinkering That's fair, but still you need a steady hand to tig weld even with that.
PLEASE add a screen in front of the turbine... you don't want to ever know the horror of something flaking or popping off in the chamber, and going though the vanes..... Nobody should have to have that happen.
Hats off to your welding, and the help you got from Mr. Vacuum! Nice job there !
👍🐈🐾🐾
Wow, huge props to Wissel Vakuum for supporting you with that adapter. That big a stainless steel flange has to be crazy-expensive, so it’s a lot of dollar/euro value, plus the owner himself helped you make it. It’s great PR for him, but he’s also very generous, much respect!
During my time as an Instrument Systems Specialist I calibrated instruments on an electron beam welding system and the chamber was big enough to fit a full size 3/4 ton utility van. It used two large turbomolecular pumps along with a pair of even bigger roughing pumps to evacuate the chamber and took well over an hour to get to the lowest possible pressure. I love science, thanks for another fun video.
😅😂😂😊
Vacuum flange adapters that size are *expensive*. You got a bargain, sir! This is a brave hobby for the financially constrained.
Servus, ich war mal Techniker bei Pfeiffer Vacuum und habe die TPH 2101 repariert und gewartet. Die Vibrationen bei ca. 10% oder auch zwischen 50-60 Hz sind normal. Das sind Resonanzen, die vom Magnetlager der Pumpe kommen und sind in jeder TMP vorhanden. Auch in den neuen Versionen. Man kann sie aber mittlerweile gut Wegwuchten.
Zusätzlich kann es sein, dass dein Aufbau (der nicht sonderlich stabil aussieht) mit der Magnetlagerresonaz zusammen sich hochschaukelt. Bei Fragen zur Wartung oder anderen Dingen gerne melden. Ich kenne die Dinger In- und Auswendig.
Hi!
Vielen Dank für den Kommentar und die Info zu den Vibrationen! Das ist schonmal beruhigend zu wissen. Ja, der Stand ist eigentlich viel zu flexibel für die Kammer und die Pumpe zusammen. Ich hoffe irgendwann ein neues Gerüst aus Stahl bauen zu können und im Boden verankern zu können.
Wenn du die Zeit hast und es dich interessiert, würde ich mich sehr freuen, wenn du dir das Video anschaust, in dem ich eine der Pumpen zerlegt habe (zwei Videos vor diesem). Als Pfeiffer Techniker bekommt man sicher Schnappatmung wenn man mir dabei zusehen muss, aber mich würde sehr interessieren, an welchen Stellen ich ganz groben Mist gebaut habe und wie es richtig wäre. Und ob meine Theorie dazu, wie das "Ölsystem" funktioniert, richtig ist. Und welchen Zweck der O-Ring am Zentierring der Statoren erfüllt.
👍
I love your set-up 😍 but you definitely should add a grid before the pump to avoid any damages on the blades if something fly in
I have a couple of different medium-sized turbos, and they both have a very distinctive spin-up sound before they go quiet, right in the initial stage of startup. It's a little scary since it sounds like it isn't balanced for a moment, but it quickly accelerates past that point. You have such an amazing setup, having so many generous donors and friends who will help out sure is nice.
If you'll be moving around anything with more mass it's probably worth the cost to get a lift of some sort. I use an engine hoist to move around machine tools and it folds up into a small size when not in use.
I have worked with these exact pumps, and yes, the vibration at low rpm is normal, just need to be clamped securely. Not sure what you meant by connecting the two turbos together to the big pump, but to make sure, you should never connect a turbo to a turbo, the pressure on the exhaust should not be less then 10e-3mbar, for only one simple reason, the oil will boil, leading to problems with bearings. The difference in base pressure is not so important, the turbovac 50 can get in 10e-9mbar region without problems, but the big one cant. The major use of such big pumps is fighting with high gas loads, for evaporation, sputtering etc... Keep up with turbo madness, this is just wonderful to see...
Thank you for that information! That's good to know.
Mh... that's unfortunate. I wanted to test what happens if I cascade the turbomolecular pumps. Considering the very low vapor pressure of the oil I would not have thought that a significant amount will vaporize.
Yes, the size of the pump has nothing to do with the reached pressure (as long as there is no leak). The only value important for that should be the compression ratio as far as I know.
I'm glad you liked the video! :)
You absolutely can stack TMPs (and in fact there are scientific apparatus that utilise such "compression turbos"). In principle you will shorten pump life on hybrid pumps, but in practise I've seen 10+ years of operation in this configuration. If you use full maglevs, I've seen 15 plus years of service.
These cascaded TMP systems are done to get sufficient compression ratios for hydrogen and helium for solenoidal ion sources and atom beam microscopes.
For some more context, these are systems that run in the 10^-10, 10^-11, and even 10^-12 mbar range.
@@mattgbarr Stacking oil lubricated TMPs is a big no-no, unless you have money, then its ok :) Of course maglev pumps can be stacked, but then again, thats for specific needs, and given the fact how much maglev pumps cost... I wouldnt do it anyway. For systems that require pressures lower then 10e-9, other types of pumps are used... Devil is in the details., money is also a big problem...
Well, of course you always have NEGs and TSPs and ion pumps. None of which serve you anything worthwhile whilst working with helium.
It's pretty much stacked TMPs or bust. Whilst a no-no in principle, it's extremely common to do so and can give you a very long service life if you use good quality units.
I was standing right next to a Leybold D2500 TMP, about 15 hp, when it went from 39000 to 0 rpm in about 1/2 second. I'll never forget that sound. One blade tip rubbed and welded to the housing, broke off and wiped the rest of the blades out. We also had an uncontained burst with an experimental Becker pump, it was like a bomb went off. We use those on fast axial CO2 lasers. Every pump we used ran through a few harmonic areas on spool up.
Holy shit!
We had that happen to a jet engine! The N1 and N2 shafts were out of alignment and able to rub and weld. The pilot had to change his pants when it went from 105% RPM to 0% in about half a second! Didn't frag the engine though.
10% load means ~3000 RPM, which equals to around 50 Hz. This frequency is the same as the grid frequency you supply your power with.
maybe this is the reason for the resonance of the motor at around 10% load.
As you mentioned already in the video, it must be an electrical resonance, because after power off, the resonance disappears. So a purely mechanical resonance is not an option.
is there a way to look at the voltages of the motor / the input power to see some sort of phase alignment?
Maybe the controller has some old caps that are not up to the task, and some extra ripple is passing thru.
Mechanical resonance is still possible an issue. If you turn it off the rpm starts changing and changing rpm will cancel out vibration.
but highly unlikely. The change in RPM is very slow because of the low friction of the rotor. When he turns the power of the motor off, the vibrations instantly stop, the rotor spins on freely with roughly the same RPM@@SaviorTheBurn
@@matze1508 I doubt a vacuum makes it low friction. Im sure pieces are pulling together tightly.
the rolling friction in the bearings doenst increase that much while under vacuum. @@SaviorTheBurn
We recently bought a used GC-MS. When we started to pump down, the noise was similar. Not so happy faces. Turns out the seller's technician forgot to plug a blind into the purge port of the turbomolecular pump. It happily drew vane pump oil into the whole system.
I was so happy it came with a 3 months warranty. Now it is running nicely.
I have a small TMP that is sketchy to use. A blade broke off it at work, so they threw it away by letting me take it home. Fortunatley, it was an ebay special because we were not treating it well (the reason the pump didn't tear itself apart was because we were evacuating a sticky process, and the side wall was so sticky that the blade stuck to the wall instead of falling into the rest of the blades).
I fixed most of the balance problems by cutting out completely the missing blade as well as the blade on the opposite side, but even though it is only a ISO-100 pump the startup is still loud enough that hearing protection is needed until it gets up to speed.
What I need to do is build up an air bearing type thing so I can properly balance it.
I've never felt particularly anxious bringing up my turbo, but watching this I was stacking sandbags in front of my monitor 😂
My understanding is that it's normal for turbo pumps to accelerate through a resonance band during spin-up, I know that mine does. Some fancy pump controllers make an effort to brake through this band on shut-down to minimize the time spent at resonance and avoid wear. I also believe Edwards talks about this in the manual for my pump in the section about venting during shut-down to brake the pump more quickly.
Take that with a grain of salt, of course, I'm strictly a hobbyist.
Awesome video once again, cheers,
Thanks! Yes, I think you can see that I was pretty nervous 😅
Thanks for the information.
Looking forward to a new video from you!
I have the same turbo pumps on my vacuum system and they make the same noises. I think 10% is where it lifts off the physical bearing. If coatings build up on the blades it will get even worse. I noticed your first pump had some coatings on the blades. I have disassembled and reassembled my pumps several times.
I work with these pumps in a CR doing r&d in semiconductor technology.
It's awesome you have these beast. But may I ask... what the hell are you doing at home with these?! :D
in our mass spectrometer we had 4 turbopumps and two rotary vane pumps resulting in a ion trap pressure of 1.4*10E-9 mbar
🤔😳🤭🤗
Lets appreciate that engineering by Pfeiffer Vaccum for a second. These turbomolecular pumps had a long productive live, are full of residue and wear&tear, have been decomissioned (probably because of that), not serviced in over a decade, dis- and reassembled by a (knowledgable) amateur.... and STILL run that well. That's how amazingly well the people at Pfeiffer designed and built them. I'm awestruck by that quality.
Nice to see in a world of planned obsolescence trash.
So much stuff like this gets such little use by universities and such and then just gets replaced because thats the name of the game. Gotta spend it all. Pokémon Labs. A subsidiary of government grant grinders in partnership with University La Ductrine; specializing in varying degrees and angles of sadist action. A fine faction to be part of.
Speaking of none sense and waste …..
When My older brother was at one of the top dental schools in the United States Inc. they were learning to work with gold and do crowns and castings and such. …,, well apparently the whole lot of them lack any sort of frugality/common sense/or that ability to always see opportunity.
I say this in relation to the fact that if it was for one person, my brothers friend; all the dimwits gold would have just been thrown in the garbage ….yeah. Soo when you work with the gold you end up with “flashing” and such. Excess gold. Well apparently they were taught this was garbage i guess? Since they were all just throwing it in then garbage with the used plaster molds and whatever. ……(i wonder how many throw away all the gold crowns they remove from people? Im guessing many do. Clueless people dentists and doctors. No business sense) ..
So his friend collected all the gold whenever an opportunity came up and for fun he made himself and entire gold “grille” for his upper and lower teeth.
Guess how much gold he got out of the trash?? Well over 10k.
And get this …
My mind instantly is running and im like uummmm sooo like is this the norm around there? Ever quarter (or semester? Whatever they’re on ) for everyone to toss their gold in the garbage. ??
“Yeah….”
😵💫
I tried to figure out how i was going to insert myself into doing free janitorial work but my brother didnt see too interested.
He was focused on worthless school.
He graduated number 1. 4.00 gpa. Every quarter.
Guess it worked out for him. He just is finishing a 8 million dollar new house in idaho. ………( its really cool …..it has solid copper gutters. ….:. Annnd it also doesnt even have a den. Or office in it for him…… did i mention his wife?? Did i mention his office isnt in idaho? Did i mention he flys home every week and sleeps in his office on a cot??……. Hmmm. His wife just had ….nevermind.
Last thing. When i met his wife before they were engaged.
Back when my brother and i were living together in the ghetto in chula vista California doing door to door sales she came down to visit ….
Thats when i learned something very unique about her….
She …..
Didnt……Know how….
To jump……
Yes. Jump. It sounds like bs. And a lie.
Nope. It was real. She thought you jumped using only your feet. Like flipper on a pinball machine launching you off the ground with hard flick of the heel toe ankle action.
Logically she saw this as the reason basketball players could jump so high. Big feet. Duh.
So rather than pointing this out to others like myself as amusement as my brother had just done i taught he how to jump….
Seriously. 🥴
And when she did achieve that first flight …soaring a quarter inch into the air..when she touched down …🎉she went ballistic.
Thats when my brother apparently knew she was the one i guess because a week later we were driving back to Seattle…….
And that was the last time my brother and i got to hangout. I had just moved down a month or two before.
Anyways he went one way and i went the polar opposite ..
I better stop. Ok bye.
Glad i got that therapy session
Thanks for listening
Ps your right about Pfieffer, really awesome precision quality creations.
And anything that is able to be serviced these days and kept alive is so important.
I have a love for vintage. Antique items of all kinds. They’re so high quality. The stuff from before ww2. Especially from the 1920’s or older.
The technology is pretty incredible. Stuff that far surpasses present day.
All sorts of electronics that utilize mercury and vacuum tubes that few even comprehend anymore.
Theres all sorts of stuff that would be claimed pseudo science by the closed mind dead clueless modern man.
If anyone is interested i can show you the newspaper articles from when a funny thing happened 100 years ago.. all this stuff cern is supposedly just learning like the”god particle” and the rest of it….
Literally , i kid you not, all discovered and more 100years ago. ….its like history is on repeat or something.
And i mean it please ask if interested. Its important to be aware of our true history as much as we can.
Buy some old issue of Science and Invention. Its really awesome.
I have one right here from 1921 and it goes into detail talking about human cloning and using cows as surrogates for carrying whatever animals or human they are cloning. Cover story is bout Dicyanin lenses and how theyre used in astro spectrography as well as for giving people the ability to see the human aura.
Turns out pre ww2 this was common knowledge. Dozen books written on it as well the many other types of dye discovered that allowed for sensitizing the human eyes to even more wavelengths. For instance layering with a carmine filter/lens would allow one to see another layer of the auric field i believe?
Whats insane is if you do search about this youll get sites like snopes “debunking” it and saying its” pseudo science “. Debunking and pseudo science… two weaponized tools of ignorance.
By the way i own three different sets of Dicyanin goggles and theyre truly amazing.
They forced me …quite literally …
To see the world in a different way. (I used to think auras were bs. So far from it and i was happy to learn this too. The world is a lot more interesting than i once believed….
In fact the world as we’ve known it is about to change. …ill leave it at that. )
No wonder a new pump like that one costs as much as a small house.
Well done on the welding! I can weld with sticks but have never tried TIG. Very nice of the company to allow in their workshop.
Thank you! The pulse setting makes it easier.
Yes, definitely very nice of them!
That's a sick setup man! Damn! I love it. Congratulations on putting it all together. Very expensive hobby indeed. You do the things I love to see. Thanks again for making your videos.
I used to work on large vacuum systems, the scariest noise after a strip down was a nut or bolt loose in the chamber just before the TMP came apart. It did happen even though we used to treat the system like surgeons and check everything we had used to make sure nothing was left in the patient!
I'm sure surgeons do the same thing lol
I suggest the vibrations are the resonance frequency of your adapter.
I would make some vertical WEBS to seam weld onto both of the flanges and onto the adapter tube.
1 web between each clamp.
It's possible that this stiffening might simply alter the resonance frequency and move it up quite a lot.
So it may then need more webs or else a new set of webs centrally mounted horizontally between the vertical webs.
First thing to try might be a few extra clamps?
"No prior experience welding"
Proceeds to absolutely *stack dimes* like he's been welding custom exhaust systems right out of the womb.
Haha, to be honest, the pulse setting on the welder makes it much easier.
That spin up began like the machine in the movie Contact.. I think your outro assessment is correct. Let the fun begin!
Pushing past the critical speed is nerve wracking for sure. Possibly while moving the initial bit of air molecules may cause inter-stage surging… try using an ammmeter on the pump to watch how much work it does. Also, if you don’t torque the clamps evenly, you could warp the bell housing on the pump. Might be the source of the vibrations…
I tried my best to tighten the screws evenly. But thank you for the advice! However, I don't believe that was the reason for the vibrations. They should be continuous if that were the case, not suddenly stopping. Also, when the pump is turned off and slows down, the vibrations don't occur at 10% speed (only at 50%, which leads me to believe that range is resonance). So, it must be related to the electronics.
@@AdvancedTinkering maybe it's a resonance between the motor coils and the esc electronics. Sort of like engine knock, as in there's a certain speed where it's not timing the phase change correctly to the coil current, and there's some sort of flyback?
@@AdvancedTinkering If you let it ramp up while the chamber is at high vacuum I suspect that you might not get any vibration, since I am guessing that it is occurring at the point where the motor is having to put in the most torque. It's still a little concerning when you first hear it since failures in the motor could cause it to push the rotor into the crash bearings, which could possible sound like that at low speeds. I wonder if it could be good practice to start a questionable pump under a high vacuum so you can know immediately if you hear any vibrations that it is likely a problem.
In industrial equipment SEMs and similar (not things made in the university physics lab) the turbo pump current was our main parameter the vac control system uses to generate faults. RPM and to a lesser extent vacuum rate also played a role but you capture some aspect of those in the turbo pump current draw.
Love this video and all the comments! I will be needing a similar set-up for MBE experiments.
1:28
That 4 jaw chuck and it’s key are worth the price of admission.
It exudes confidence and strength.
Great video. Thanks
Subscribed. As a Graduate Engineer I spent 2 years in a Semiconductor factory process line working around various vacumn pumps, implanters etc
My Balzer vacuum evaporator used a Pfeiffer turbomolecular pump. I had to replace the pump at one time and since I lived and worked within 10 miles of the Pfeiffer factory near Wetzlar I got a tour of the factory, as well as a new pump. Compared to oil-diffusion or ion-getter pumps they are certainly simple and reliable. One of our electron microscopes also had a TM pump. I was a bit leery about vibration, but it was not a problem. You probably will want to put a screen in front of that pump.
I completely agree with others about your welds. A nice bead. Not overly hot. You could have easily warped the flange or cracked the weld on the opposite side. I’ve seen seasoned welders destroy 316. Pulse mode or not. Excellent.
Aaaaand now I have to go and watch video of sevicing the turbomolecular pump. That's yet another knowledge that I will never need in my life :-D
You never know when being able to disassemble a turbomolecular pump might save your life ;)
Excellent video! The harmonic and resonant vibrations which occur at those speeds are very hard to understand. Your pumps sound pretty good to me!
This makes me think of my best friend who worked with vacuum equipment and other lab kit for his career. He passed at 48 years old this year unexpectedly.
Looks like you got yourself a turbo-spectacular machine :)
Having been in a passenger aircraft whose auxillary turbine in the tail no longer worked, slowly externally starting a jet engine has a similar resonance that goes away at full speed. This is normal.
My best guess as an engineer: Run through the band of resonance as fast as possible. I heard of a hydroelectric plant that had an accident because it stayed in the unsafe operating area of resonance too long. Also use a sandbag ring or lead shot bag or something to damp it out and reduce the hazard.
Very nicely done, really enjoyed the spin up footage I’m stoked that you even got the internal footage lol cuz getting to see and hear the resonation was really cool, glad ya did that!
The vacuum created is awesome, by definition of the word awesome. The welds are way better than I have ever been able to do and before multiple sclerosis took over my nervous system I had been an auto mechanic welding professionally.
very nice pump👍
The folks over at r/welding would give you A+
It's amazing how my expirience is similat to yours. But I am working as mad scientist in former USSR lab and we have like 100 or somithing old but usable turbomolecular pumps so we are not so worried with sounds its produce as you x) I'm really interested in what you doing with your vacuum chamber, what are your plans? Any experiments? Plasma coating? I'm really want to invite you to my lab, but it is probably unlikly and hard to achieve.
Someone is selling a TMN-500 right now...which is interesingly a horizontal pump with magnetic bearing...and 36 stages!
imagine doing Schlenk chemistry with this beast
Yes, in my opinion Schlenk line would implode… as we talked lastly in comments - we can now try who was right ;)
@@mgrzegthe most force a vacuum can put on anything is 1 bar, changing a bit depending on the weather
Extreme overkill unless you were building large arrays of stuff that off gassed a lot.❤
The scary noise coming out from the TMP is due to the mecanical forces induced in the rotor by the stator. Is like when you hear a big generator starting, the electromagnetic field of the inductors make shake everything. So when the motor does all the hard work of acceleration you get all those noises and vibrations, and as soon you start getting closer to the desired spining regime the motor only have apply force to keep the movement. at the desired conditions.
Thank you. In fact, not so many ppl can have a chance to wintess real work of equipment that level.
Those welds are beautiful
Thank you!
This is some of the coolest content on youtube, love it man!
Thank you!
Your artifact at the 10-6 region can be 1-pinholes in welds (virtual leaks) 2- compounds boiling off and burping (fingerprints , vacuum grease etc) 3-actual very small leaks 4- permeation through o-rings or pin holes.
Now I'm no weldician but for a first weld that looked noice
A lot of devices that spin have an RPM range that they have to pass through during which there are resonant oscillations. Once the device is spinning faster it is no longer a problem. Therefor the device usually has a warning about not loitering at certain speeds. Fancy nuclear centrifuges come to mind, there is a RPM range where they will self-destruct, which is what that Stuxnet virus exploited. I wonder if these things are similar, since you can clearly see the vibration increasing until it starts making that noise.
They are similar indeed. In these turbos you can tell apart the critical speed due purely to the rotor moment of inertia from any other resonance due to the motor drive (and not rigid enough mounting) if you pay attention to the spin _down_ behaviour, where only inertial phenomena would make themselves evident.
@@SVanHutten ah, I see
Yes they are extremely similar to gas centrifuges, magnetic bearings and all. ❤
This is equally fascinating and terrifying.
Resonance was my first guess too, but now I'm guessing that at 10%, there might be more reactionary force being applied by the air in the chamber to the blades of the pump than before the chattering starts or after it stops. Maybe, before that point in the startup, the pressure in the chamber is "high", but the blades of the pump aren't going fast enough and aren't imparting enough force to shake the chamber. Afterwards, there's very little air left, so, no matter how fast the blades spin, they're imparting very little force, which means there is little reactionary force. To test that theory, you could evacuate the chamber to a mild vacuum using a standard vacuum pump, then disconnect it and start the turbomolecular pump. If the chattering doesn't happen or happens at a different point in the startup of the turbomolecular pump, then this would explain it.
Or, maybe it's caused by differences in relative pressure on one side of the chamber vs the other. Eg. there's a small enough pressure of gas in the chamber that differences in pressure don't propagate very quickly, which would cause a sort of slosh from side to side, causing one side of the pump to hit more air molecules than the other, imparting imbalanced forces on the unit and causing it to shake.
Just stumbled on to this channel, Instant sub. Amazing, Educational, And funny too. Thanks so much :)
Thank you! I appreciate it!
Awesome work! The vibration around ten percent speed could be an interaction between the control loops in the motor driver and a mechanical resonance in your setup. Since it disappears when the controller is powered down, this seems like the most likely candidate to me. Are there any specific pump mounting requirements from Pfeiffer when it comes to rigidity or vibration?
Very interesting. If I understand you correctly, you're suggesting that the resonance prompts the control electronics in the controller to counter-regulate, and these two aspects exacerbate each other?
@AdvancedTinkering in my setup in the lab I use a piezo stage which is controlled by a PID controller. Maybe the motor is controlled by PID as well? PID controllers often have resonances if combined with setups that have resonances as well. My stage, untuned, has two or one resonances at certain frequencies. You can tune these by applying a notch filter. Roughly speaking, a notch filter makes the controller not do anything at certain frequencies, which is better than doing something and creating a resonance. Making your setup more stable/less top-heavy might also work
@@AdvancedTinkering That's it. When the mechanical system has resonant modes and a method for these to couple with the electrical control system, then interactions like this can happen. It depends a lot on the details of the motor control scheme and controller bandwidths, they might use anything from open loop V/Hz control to field oriented control with nested current (torque) and voltage (speed) loops. I have a few different pumps and controllers, and there is a lot of variation here, with larger pumps generally having more advanced control schemes. This is just speculation on my part, but if you want to look further into this, it might be verifiable by looking at the motor phase currents, to see if there are any unexpected frequency components there corresponding with the mechanical resonance. This could be done with an oscilloscope and a shunt resistor, but I would be careful about introducing any components between the controller and pump, and the voltage is likely also floating relative to the oscilloscope ground. I'd prefer a contactless sensor instead, like a clamp-on oscilloscope current probe, if you have access to one. Looking at the motor phase voltage might also be useful, but probably a lot less clear since it tends to be a pulse-width modulated square wave with the output amplitude encoded in the pulse width.
Thank you for this incredibly informative comment! This is why I just love UA-cam comments! Unfortunately, I currently don't have access to an oscilloscope with a non-contact current probe, nor do I probably have the expertise to interpret the data readings accurately. However, it's definitely going on my list of things to test in the future!
Thanks for the info! Yes, the stand is way too top-heavy with the pump. Once I have more space, I'll build a new stand for my chamber that hopefully can also be bolted to the floor. Right now, I need to be able to move the chamber and save space, so it's my only option at the moment.
That's a heck of a machine.
deamn these welds lock good
Thanks!
Wow! You are a natural at welding😮
I worked for a tech-firm that x-rayed power supply modules...insurance purposes.
They beat the heck outta their turbo pumps...their operating procedure called for pumping down the x-ray tube every morning, running it hard all day, then cooling it down at the end of the day with 'air flooding'.
Yup, they let the air in at night, then played with the filament in the morning before pumping it down again.
In the 4 years I was there, there were two instances where the filament had any problem that needed attention.
The technician who wrote the 'instruction manual' is now head of an entire Division...of course his instructions will never be reviewed...it would reflect poorly on the Great Man.
Apparently replacing turbo-pumps was cheaper than re-writing the instructions.
To rule out the vibration coming from the mounting structure, I'd perform a frequency range test on the setup and determine it's natural frequency.
It might be that the natural frequency of the structure is the same as the pump at 10% output - which would explain why it was observed on both pumps, and that the resonance disappeared when the pump frequency increased.
Amazing machine!
It really is!
But also intimidating!
i've never seen a turbomolecular pump used upside down, i just assumed they all work "right side up"
This pump actually has to be used “upside down” or on its side due to the oiling system. In my video about the disassembly of that pump I briefly talked about that.
Mr vacuum thank you!
It's safe enough lol. Great engineering.
First off all: interesting work! At work we use smaller TPs and I just had short resonance windows with very old pumps. But our chambers are also more massive. Your TP/chamber ratio is a bit...off😅
Since you did a oil transfer between the pumps, I guess the high pressure side is oil lubricated. In this case the upside down position should not be used (check manual). Only dry lubricated pumps or such as maglev can be mounted upside down.
Your rough pump is a bit small for this huge TP. Pump down performance of the TP is restricted in this setup. Pumping down just with the ratary vane pump may cause oil contamination since there might be a non laminat flow of oil molecules to the chamber. So I suggest never running the rough pump without the TP, since it will prevent molecules getting in the chamber.
For better pressure you should think about switching to cf and do a bake out. Then X^-10mbar is no miracle. Downside ist you need to replace the gaskets every time.
Hope this didn't sound too much like bad criticism. I'll just wanted to share some (hopefully) useful informations.
Keep up the nice work!👍
Still cannot believe you traded a few cases of beer for these plus the controller. 😮 That is better than you could do at a US hamfest.😂
You can get that resonance from PWM type motor controls. PRF do not have the same issue and neither do analogue controls. The trick is usually to select a PWM frequency that produces resonance at low speeds so that less power is available to cause vibration if it is not possible to get out of the resonance range.
Bravo!
Rotating anode X-ray tubes have a region of resonance similar to what you have experienced. They are driven quickly through this region to minimise the time that the resonance is experienced. Data sheets on driving rotating X-ray tubes may offer some insights into the mechanics involved. When turning off, the speed is controlled by electrical braking to minimise the transition through the resonance speed region. The drive electronic variable frequency drive should be matched to the mechanical load both driving up to max speed and returning to zero speed. The manufacturer of the turbo molecular pump should be aware of this phenomena and have or be able to suggest a suitable speed controller.
it's probably just passing through an RPM that causes harmonic oscillations with the structure of your setup when it's spinning up
I have seen whole movies that had less thrill, emotions, high-tech and all without special effects. :D
those equipment manufacturers must really like you, i wouldn't trust anyone certified to weld a part i made, let alone one dealing with vacuum and possible leaks and contamination.
This guy is great! I felt bad tho. You can definitely tell he was so worried! Lol I dont blame him tho, that's a very nerve-wracking experiment!
The noise is very likely turbulence during the most dense stage of operation.
Check the psi and see if at the time of the noise, if it is fluctuating.
This would likely be the cause as the Air leaving will have a small stage of higher pressure as the Vacuum pump can't vacate as quickly as it is ramping up.
(bouncing from a zone of high pressure to the lower one and back again until it finally moves out of the system and balances out.)
Then there will be a drop-off as the vacuum finally eases past this "cliff".
That was very cool! I could almost feel all the stress over my screen
I’d expect some of the resonances are actually compressor stall phenomena. The recommended maximum startup pressure could be limited by at least:
Maximum thermal load on motor
Maximum motor current
Allowable bearing loads
Allowable time passing through a mechanical resonance
Compressor stall
The turbomolecular pump is an air compressor, and if your roughing pump is unusually small, the turbo will get ahead of the roughing pump capacity to remove enough gas from the outlet.
There is also the transition in operation as the mean free path changes from less than to greater than the relevant dimensions.
The easy test is to either pump down a bit further before starting up the turbo or to pause the RPM increase below the resonance for a bit and then continue the run up, and see if your behavior changes.
Monitoring the roughing pump inlet pressure and the chamber at separate points would be ideal.
I noticed the sound that the pump makes while vibrating is around 60hz. Maybe an interference of some sort with the main ?
He is in Europe, we have 50Hz here
That I say is very unlikley since the VFD retrifies the AC 50/60 Hz input to DC and also evens it out with some really large capacitors before it gets sent to the IGBTs. If any of the mains hum would have got though then that inverter I say have a crappy retrification and fitering stage wich would be very unlikley for a manufacturer of high end vacuum equipment to skimp on. The inverter drive is most likley built to just as high standard as the pump itself as these things are meant to run for years on end non stop in higly critical applications where failure is not an option.
Reminds me of all the scary noises and vibrations when they start the engines of an airliner ....
Resonance frequencies are meant to be quickly surpassed or not reached. However, at the high rotational speeds of the turbopump, amplitude resonances are usually encountered. / Resonanzfrequenzen sind dazu da, schnell überfahren oder nicht erreicht zu werden. Bei den hohen Rotationsgeschwindigkeiten der Turbopumpe werden jedoch meistens welche erreicht. (Amplitudenresonanz)
I deal with these pumps all the time at work (semiconductor chambers etc) and every time I hear some turbo pumps spin up cause they sound like they might explode until up to speed lol
My guess on the violent shaking at lower rpms (if not resonance) would be that the motor and fan are balanced for 30k rpm operation. potentially due to materials expanding during operation from the centrifugal force, inconsistencies could make minor imperfections in balance at rest.
Disclaimer: I know nothing about vacuum pumps or things that spin in general
Vibration as things spin up are well known, all that can be done is to push through them quickly. Imagine doing that with a steam turbine and generator weighing hundreds of tons. Part of the art of designing big spinning things is ensuring the vibrations don't happen at operating speed.
Right on. Now run both of these bad girls together. Super jealous, friend. congratulations
we had pumps like that at the lab (physics uni)
those things are dope, if you can use them for something
Many centrifuges also make strong vibrations from resonances at some lower speeds than their maximum. Just got to power through it.
2:58
I don’t believe the o-ring would have popped out unless mounting ring was deflected in some way.
Perhaps you could check it’s flatness next time it is available. I am just curious.
Nice to find your channel. I appreciate thick meaty science content. You have it in spades.
Enjoy your Sunday.
So interesting, easy to listen to. Subbed here.
Thank you! I’m glad you like the videos!
Nerve wracking. Crazy that it works after so well. As of the pressure spike, looks like calibration is required for the pressure sensors, so the two modes match well during switchover. I do know nothing about vacuum systems tho.
Well done, possibly if you evacuate the chamber at 10% power for 20 minutes then switch to full power you may bypass the standing wave. If you go to my video on the most accurate gun in the world you will notice the small turbine that spins the gun barrel goes through a few standing waves before it reaches 1Khz (60,000 RPM) which is to be expected because there is a lag between the air jet, vanes and reflected air. The turbine settles down when the angular velocity is constant, but still I am with you its scary, and my turbine is home made.
Watch out for flakes of deposited metal if you do deposition, can short out your gauge and I wouldn’t want any bits to get into the turbo!
good job!
We don’t like the TMP mounted free above the chamber. Remember, everything is a spring. Mount it down in the stand, where it can’t bounce around.
It's not clear from the manual of that pump what active vibration compensation it might have, but mag-lev turbo pumps especially need a stiff chamber to mount on so that they can "push against" the chamber to compensate for internal vibrations. If your chamber or the supports are wiggly, you can create standing waves between the chamber and vibration compensation or rotor and you *can* destroy the pump from this vibration (ask me how I know). Also, claw clamps are not a safe way to connect turbo pumps because of the rotational inertia. If the bearings seize or there is some other problem with the pump, the pump will go flying off your chamber. You should use full ISO bolt rings instead.
hell yea.. maybe some really interesting experiments coming
Video emozionante !!! 👋👋
I can confirm that resonances in low ranges are a thing.
Lab centrifuges have resonant frequencies at around 600 - 1000 rpm.
Also, could one of those resonances (either in the low range, or at 50%) be acoustic resonance?
I believe vibration is due the air in the chamber compressing out and Bounce back to the blade, and if you stated to empty the air in the chamber using small rotary suck ion pump to empty all the air already the turbo pump blade should not need to over load it work as it spinning up!
Amazing machine but I still have a thing for the elegance of oil diffusion pumps.
is that profile frame good to hold all this heavy and spinning equipment?
No, definitely not. Without the pump and just for the chamber it's completely fine.
But using a pump like that on a frame like mine is not what you would consider safe.
it's probably also the source of the resonance, could even be multiple modes cuz there's so much mass at the top@@AdvancedTinkering
I initially suspected that too. However, what made me suspicious is that the noise stops so suddenly. Even when I switch off the pump, it stops quickly while the rotor continues to spin at practically the same speed. Also, when the pump skows downfrom full speed, I hear a noise again at around 50% (which I suspect is resonance), but not at 10%. If it's only the rotation of the rotor, I should hear it when the pump slows down as well.
@@AdvancedTinkering yea it is curious, but mounting it on something solid would eliminate some causes.
Wow, mad respect to Mr. Vacuum.
$500 for one liter what? Why?
The degradation of the pump veins will cause unbalances in the system. This will result in harmonic in certain frequencies. But it seems the motor driver creates the vibrations. This could be because the driver tries to hold a speed before going up further. If the control loop goes in harmonic with the rotation it can shake it self apart. Normally the driver would go in a different mode if such a harmonic situation is detected. If restarting the pump controller at speed solves it, then it looks like the driving system has a problem in detecting the frequency or the rotating mass correctly. The first would point to the power consumption detection, the second one to the initialization routine.
Based on how much smaller your roughing pump is relative to those massive turbopumps, there may be some effects caused by a rise in foreline pressure during parts of the pumpdown.