NSK’s Super-TF Main Bearing Solution

You may have missed this fantastic with Loren Walton from NSK, so
we're sharing it again. He discusses the challenges of main shaft
bearing failures in wind turbines and NSK's Super-TF bearing
technology as a durable solution. Loren also covers the limitations
of previous diamond-like carbon coatings and how NSK's advanced
heat-treated steel can improve turbine longevity. Fill out our
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technology. This episode is sponsored by Weather Guard
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YouTube channel here. Have a question we can answer on the
show? Email us! Allen Hall: With modern wind turbines growing
larger and main shaft bearings failing prematurely. The industry
needs innovative solutions rather than relying on yesterday's
technology. This week we speak with Loren Walton, manager of
corporate accounts at NSK. NSK has developed super tough bearing
technology, a special heat treated steel that creates a
significantly harder surface without coatings delivering long
lifespans and eliminating catastrophic failures in today's larger
wind turbines. Welcome to Uptime Spotlight, shining Light on Wind.
Energy's brightest innovators. This is the progress powering
tomorrow. Allen Hall: Loren, welcome to the show. Thanks for having
me. Appreciate your time today. Loren, we brought you in the
program because you're an expert in bearings. You're with NSK, A
lot of knowledge, a lot of history there. First, I want to ask a
real simple question because we've run into operators all across
the United States and the world. Generally speaking, we just got
back from Australia who are having problems with main shaft
bearings. And maybe the first thing to do here is to describe what
some of the problems are that operators are facing with the
traditional main shaft bearings. Yeah. So Loren Walton:
traditionally what we were saying was a whole lot of, I guess I'll
say combined loading, right? So it's a, radio load that is, up and
down and some axial thrust that's coming in from the wind shear,
right? So combining the weight of the main shaft, which is you're
taking up from that radio load with that wind shear. So then you
end up having some combined loading where. The downed wind row is
seeing a little bit more of load share than the upwind row. That's
getting through the lubricant regime, which is then creating some
micro welding and shearing, any amount of metal, any steel. When
it's created, it's going to have some disparities. I use my fingers
as the disparities, right? So your roller, your raceway, or your
raceway, your roller. There's gonna be some welding and shearing
that happens when that is under high pressure. And so your
lubricant is supposed to create a little bit of a gap between
those. When you don't have that gap you end up with the welding and
shearing, you end up with what we call peeling damage, and then
that peeling basically goes over and over again, and you start
having high levels of debris. Inside of the system. And then once
that debris starts going all bets are off, right? 'cause you can't
really even model debris very linearly. It just goes into
additional sping and then you end up, if you keep letting it run,
you end up with a through crack inside of one of your components,
which is typically your inner ring. 'cause it's press fit on the
shaft. Joel Saxum: And a important concept here as well is because
main bearings are basically a sealed lubricant system. There isn't
filters on these, right? So like when you start to get debris
moving around in the system, it stays there. It just, it's not oh,
let's go change oil on this thing. And we remove the debris, we put
a new filter on it, we're good to go. It's not, it's just, it's in
that system now. If it, because it's a closed loop basically,
right? Correct. Yeah. So the grease shift is in there, Loren
Walton: there is an opportunity for you to have, replenishment,
right? So you can put new grease in so that old grease comes out.
But even then, you're reliant on gravity and whatever you can get
out of the system. You're hoping that as you put new grease in, old
grease comes out. But depending on how long you've been running, it
is very possible too that you might end up putting new grease in
and new grease out, right? Because the old grease is so stuck in
there. Is now hard to move. It's very difficult to get that old
grease to actually come out. So depending on, if you have maybe a
auto lube system or something like that, it might be, you might be
running that grease a little bit more consistently. Otherwise,
yeah. You're stuck with what you're stuck with once that debris
gets going. Allen Hall: So what you're saying is as the weight of
the shaft and the rotors, everything has gone up on basically two
and a half megawatts seems to be that critical area. And above
that, depending upon the bearing design, the coatings or the
finishes combined with the lubricants, you can actually, or what is
happening is we're micro welding the bearings together because of
the weight and the, just the the friction that's between those two
things that. I don't think anybody from the technical side realizes
it's happening. It's not something you think about in a bearing.
That gets me into the next question of obviously the bearing
manufacturers try to treat the bearings some way to prevent that
from happening. It seems like diamond, like carbon coatings were
the solution a couple of years ago. Why was that chosen? Why did
that thought process happen? Is that something that was successful
previously on smaller turbines and was this implemented on the
larger turbines or what was the engineering behind that? Loren
Walton: Yeah, so I started my career in the when generation space
in bearings somewhere around 2011. And at that time, that was when.
We were moving from the kilowatt class to the megawatt class
turbines. And that was when we first started seeing a whole lot of
main shaft bearing problems. And it is all the stuff that I just
described, right? The micro welding the micro welding, macro micro
pitting, leading the macro pitting, leading the sping, all that
stuff, right? So that was something that was very prominent once
you started going from that kilowatt class to that megawatt class
and to combat that. DLC was introduced and the thought there was
you have a dissimilar material. So what I just described is that,
again, I'll bring my disparities back that micro welding happening,
that welding and shearing. That only happens because you have two
of the same like materials. That doesn't happen if you have a
dissimilar material. So DLC di like carving. So what you have is an
amorphous tsin carbide that you adhere to the surface of one of
those components. So in this case, the roller is what you adhere,
the amorphous tsin carbide too. So that was a game changer. That
was huge, right? We went from a few years of life, maybe on average
three to five. To I remember seeing a report where A DOC bearing
came out after 10 years and still looked beautiful. It was, sorry I
like bearing, so I use terminology like beautiful, right? That I
don't know if that I caught myself after I said the word beautiful
for bearing, but that's just, bear with me. So when we were doing
inspections on some turbines that were greater than two megawatt we
found. Some abnormalities, we'll say, in some of our inspections,
we didn't expect to see certain things that we started to see. We
started to see more issues on the inner ring instead of the outer
ring, we started to see more issues on rollers than we had seen
before. And these were on coating rollers, right? So somebody had
already gone to the solution of DLC because it had worked before.
And in this case, the customer we were working with. They actually
shortened their life. They went from four years of operation to two
years of operation on average when they were using a product that
had the coating on it. So again, an abnormality, something that we
weren't used to seeing. So we did all of our investigations, all of
the inspections that we normally run through. We saw that there was
actually damage to the DLC. There was the DOC was being harmed. We
saw that there was also subsurface wide edge area, wide edge
cracking that was also in, in the inner ring and in the rollers. So
then we saw that when you compare the uncoated to the coated, the
once the DOC was harmed, now you have actually an accelerant to
failure. It. It wasn't that the DOC was wrong, there was nothing
wrong with the DOC. But once it was harmed, you had an accelerant
to failure. So instead of it lasting about four years, you're
saying it lasted two years. Joel Saxum: When you have starting to
have a failure with DLC, what are the things that an operator
should be looking for, whether it's a, the DLC ones, because
they're very common right now. The, in the say the US fleet, there
is a ton of DLC coded bearings out there. What are things that an
operator should be looking for to see a failure before it turns
into a really big problem? Loren Walton: Yeah, so you'll primarily
see some amount of vibration signatures in your rollers is what
I've understood from some of the people that I've talked to. It's
really hard to see though, I think. I think that is still getting,
like people are still getting better and better at identifying it.
Unfortunately, in a lot of cases, what you have to do is see. If
you have to look backward on your vibration to see, okay, this was
the point because in a number of cases, you might look on Monday,
let's say you see it on vibration,