Show notes
Loren Walton from NSK discusses the challenges of main shaft bearing failures in wind turbines and NSK's Super-TF bearing technology as a durable solution. He also covers the limitations of previous diamond-like carbon coatings and how NSK's advanced heat-treated steel can improve turbine longevity.
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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, you go do a physical inspection and the rollers look fine.