The dashboard aims to improve operators ability to reduce costs and make long-term planning decisions based on in-depth data drawn from a range of critical sources. These include: condition-monitoring systems, estimated remaining useful life, and the lead-time of replacement parts.

The Wind Reliability Dashboard is currently being tested in the field by Boralex.

The Wind Reliability Dashboard is an evolution of SKF’s current condition-monitoring and predictive maintenance tools. It extends existing capabilities by allowing data to be captured and analyzed from all forms of rotating systems in each turbine, from both SKF and other CMS providers.

“We have been working closely with the SKF engineers on every step of the project from the definition of functional needs, through the core development of the device, to real-life condition tests, in order to help SKF refine the dashboard model,” said Jérôme Gardyn, CMS Analyst at Boralex.

Typically, it keeps track of components actual and remaining service life, based on previous detection CMS cases. This creates a reliable component library, which allows the move to predictive maintenance via better risk management.

The dashboard also captures information from maintenance systems as well as from the supply chain. For example, it allows the matching of replacement spare parts lead-time with remaining useful life of the component.

Ultimately, it can provide external Systems like CMMS (Computerized Maintenance Management Systems) the key indicators for maintenance best practices, components MTBF (Mean Time Between Failure) & lead time.

“Wind-farm operators are under increasing pressure as growing numbers of turbines fall out of warranty and as market price for renewables gets more and more challenging,” said Jonathan Day, Analytics and Digitalization Development for SKF. “Identifying ways to reduce OPEX and protect margins is therefore crucial. This is the driving factor behind our Wind Reliability Dashboard, which will help each operator improve the efficiency of their business.”

Day added: “The dashboard allows operational and business management teams to communicate far more effectively about critical turbine maintenance and planning issues. It also makes it easier to identify and predict drive train issues, manage spare parts logistics and reduce risk, by enabling data driven decision-making.”

Jan Levander, Project Manager Supply Chain 4.0, commented: “We have in the dashboard also managed to add direct links into SKF supply chain availability information using Supply Chain 4.0 logic to ensure and optimize stock planning and to reduce overall cost.”

The post SKF and Boralex developing wind-turbine reliability dashboard appeared first on Windpower Engineering & Development.

By David de Garavilla & Dr. Xiaobo Zhou
SKF

The renewable energy sector is being forced to reduce the levelized cost of electricity (LCoE). The wind energy industry is striving to match or exceed the LCoE of traditional energy sources. Due to the cost of the equipment combined with the lower relative operations and maintenance costs compared to traditional energy, the driving factors in reducing the LCoE in wind are the costs of the equipment and uptime.

Uptime in wind turbines is critical to the future of the energy source. In the past years, SKF scientists and research engineers conducted systematic investigation and verification tests on key parameters, which may have strong contribution to the main-shaft bearing performance.

Common main-shaft spherical roller bearing outer ring damage, upwind row left, downwind row

According to the investigation, following parameters have been identified:

• Lubrication starvation can be a direct cause of bearing failure, which will result in fast wear and surface distress (micropitting). This can lead to edge load on the wear grooves resulting to so-called spall bands in circumferential direction of the bearing raceways.
• Lubricant starvation is the result of the lack of grease in the contact and oil depletion in the grease.
• There are many parameters which have been identified to accelerate lubricant starvation, such as incorrect selection of lubricating greases, improper re-lubrication method, high friction, high sliding to rolling ratio, low lubrication film thickness, etc.

To reduce the risk of lubrication starvation, SKF NoWear surface coating has been selected and verified, which can not only increase the wear resistance on the raceway surfaces, but also reduce the friction and therefore prolong the grease life. NoWear testing has shown performance upgrades by reducing wear in the starved condition, and more critically to overall asset life, extending the time to starvation when compared to a non-coated roller bearing.

SKF NoWear is a wear resistant metal-containing hydrogenated amorphous carbon coating that is applied to the rolling elements of spherical roller main-shaft bearings. A physical vapor deposition process applies the wear-resistant, metal-doped, diamond-like-carbon coating. Thickness of the coating ranges from 0.6 to 6 µm, depending on the size and geometry of the bearing. The nano-indentation hardness of the coating is 12 GPa (~1,200 HV).

NoWear coated bearing surfaces retain the toughness of the underlying material while adopting the hardness, improved friction properties and wear-resistance of the coating. The dry sliding coefficient of NoWear against a steel counterpart is less than 0.2 while that of bearing steel is 0.6 – 1.0. As such, NoWear coated bearings can operate reliably even where adequate surface separation cannot be achieved. NoWear acts as a protective layer and may reduce the need for Extreme Pressure (EP) additives in the lubricant. This is beneficial in wind-turbine main-shaft applications, since EP additives should be avoided if possible as they can contribute to the generation of micropits.

NoWear is a proprietary formulation patented by SKF and is constructed with three layers. The run-in layer at the surface, the functional layer in the middle and the adhesion layer attaching the coating onto the underlying steel component surface.

The adhesion layer is particularly important for bearing performance when compared to other coating formulations. The formulation allows for optimal adhesion and high elasticity, while maintaining high hardness for wear protection. This strong adhesion is fundamentally important in bearing applications to prevent coating material from becoming a contaminant in the system if it flakes from the substrate.

In addition, the NoWear coating achieves running in over a shorter period when compared to other coating formulations. The NoWear formulation is the preferred solution for surface fatigue or micropitting due to its low friction and running in which reduces the induced local Hertzian stress.

Before discussing the SKF NoWear testing and verification in the main-shaft applications, it’s important to first understand the lubrication regimes the bearing operates to understand the resulting damage.

The following regimes are established.

Main-shaft bearing lubrication regimes

The green zone or desired operating regime occurs when lubricant is correctly selected and fresh grease is supplied to the contact. Little wear of the raceways is occurring, only smoothening on the micro level. The blue zone or mild wear regime occurs when lubricant is losing base oil content that is incorrectly selected, or insufficiently supplied to the contact. In this regime, mild wear or p*V (p: contact pressure and V: sliding velocity) like wear in the ~0-10 micron level occurs, where there is polishing but no surface distress.

The third regime is the red zone or starved regime. The red zone occurs when lubricant is below critical levels in the contact. Aggressive wear, surface distress (micropits) and high material removal are characteristics of the red zone regime. The time it takes to damage the surface in the starved regime is shorter when compared to bearing life and the typical maintenance intervals of six months.

SKF NoWear coating layers

Therefore, if the red zone is reached in the application between maintenance intervals, surface damage is irreversible and the designed-for-load distribution across a rolling element can no longer be ensured and further damage may be accelerated due to the loss of geometry.

A common damage pattern of a spherical roller bearing (SRB) outer ring from the main bearing is shown in the following image. On the downwind row (right), a deep wear groove in the mid-raceway is observed and micropits fully covered the surface of the wear groove. Circumferential bands of spalling are presented on either side of the wear path, which is a result from the loss in profile and higher contact stresses at the edges.

These damages are seen primarily on the more heavily loaded downwind row.

Micropitting test results
The first set of application-specific SKF NoWear tests was a component level test. A small-scale experiment that could replicate the surface damage seen in the application. In a series of component level tests with a micropitting test rig (MPR) the objective of replicating the damage mechanism is possible.

Micropitting test rig (MPR)

The MPR test rig is comprised of a single roller at the center with contact to three rings

Test conditions were set to maximize the damage within an acceptable time frame, while also maintaining application conditions. These tests would recreate the heavy damage period of the application where starvation has occurred in the contact. This would be considered “red zone” conditions. Tests measured both the time to starvation and the mass after test halt compared to pre-test weight to calculate wear. The test matrix included three samples of steel on steel and steel on NoWear coated surfaces.

The results indicate the SKF NoWear coated surface significantly limits the amount of wear once the starvation (red zone) conditions are reached. Based on this component level test, the time it takes to reach the red zone conditions are scattered across the samples and no correlation is noted.

Of the six samples, one steel on steel and two steel on NoWear samples operated for one hour after reaching the starved regime. The amount of wear during the hour after reaching the starved condition for the steel/steel contact was 22.02 mg, while the wear for the NoWear/steel contact resulted 0.77 and 0.18 mg, proving that NoWear coating reduces the damage after lubrication starvation occurs.

MPR test cases one hour of operation after starvation. Steel on steel (top row), SKF NoWear on steel (2nd and 3rd row).

However, since the duration of the red zone during the total life of the application is short or at the very least unknown, the next question to be answered is whether NoWear can prolong the time to lubrication starvation. As the MPR test rig was not suitable to answer the question, another test rig and matrix were established.

LAD testing results
The second level of testing was designed to answer the question of whether SKF NoWear coating can prolong the time to lubrication starvation. In other words, could NoWear delay the onset of the red zone in addition to the benefits shown once within the red zone. For these tests a full bearing was needed and a test rig known as an LAD was used.

The LAD tests measured the time to starvation or sharp increase in friction. The LAD test matrix includes both the all-steel bearings and SKF NoWear coated roller bearings.  In addition, two types of greases were used for the LAD testing.

A recently developed main-shaft specific grease with base oil viscosity of 670 cSt and a common wind turbine main-shaft bearing grease with base oil viscosity of 460 cSt were chosen for these tests.

As done in the MPR testing, conditions for the LAD tests were set to replicate the application conditions. Producing a starved condition in the steel on steel samples within a time frame of approximately 100 hours was targeted in pre-tests. For all samples any test that had not failed at 480 hours were suspended.

The final results
The results of the LAD tests indicate the SKF NoWear significantly extends the time to starvation. Differences in the performance of the LAD test samples were noted between grease types, but the larger difference is noted between the steel and NoWear coated roller samples.

Considering the NoWear sample tests were suspended at 480 hours, the median time to starvation was more than 5x compared to the non-coated bearings.

In addition, a single data point was captured that was not suspended. A 460 cSt grease sample was allowed to run out and achieved 2,584 hrs. For this sample the time to starvation is greater than 26 times compared to the median non-coated sample with the same grease.

Testing and verification of SKF NoWear during development with the coating supplier shows the coating provides advanced wear protection in poor lubrication environments and reduces surface fatigue or micropitting. With the addition of SKF MPR testing, NoWear coating significantly reduces the amount of wear once the bearing contact is starved.

Furthermore, with the addition of the LAD testing, the reduced friction within the contact and improved run-in enables a NoWear coated roller bearing to significantly extend the time to starvation, which is critical to bearing service life.

LAD test results: Median time to starvation or suspension

SKF has been supplying NoWear coated bearings for applications including:

• Paper machines
• Marine and offshore
• Fans
• Compressors
• Hydraulic pumps gearboxes
• Hydraulic motors

The test results validate using SKF NoWear coating technology in rolling elements significantly increases main-shaft bearing reliability, with the goal of reducing LCoE in the wind energy segment.

Acknowledgments

David de Garavilla

The authors would like to thank Jeff Marchozzi and Dayananda Raju, for their dedication to allocating resources that drive innovation in the wind energy industry at SKF. The authors also thank Arnoud Reininga, for his kind permission to publish this work.

The authors…
David de Garavilla is an application engineering team leader with SKF USA, Inc., based in Lansdale, PA. Mr. de Garavilla has 14 years of experience at SKF with every major industrial application of rolling element bearings with an emphasis on data analytics, modellng and simulation. He specializes in main shaft bearing applications.

Dr. Xiaobo Zhou

Xiaobo Zhou, who has aPh.D. in Applied Physics, is currently working as a program manager in SKF Research and Technology Development in the Netherlands. He has 24 years of experience at SKF in coatings, materials science, tribology, lubrication, sealing, root cause failure analysis and application-driven innovation for nearly all SKF bearing products.

The post Extending main-shaft bearing life in wind turbines appeared first on Windpower Engineering & Development.

This week, the company hosted a press event in Philadelphia (its U.S. headquarters is in Lansdale, PA) to share insights on what it has learned and what’s new. One of the most relevant changes (or progressions) of its time: digitalization.

Connected devices, via the internet of things, provide business or plant owners the ability to monitor, control, and operate assets no matter how much distance separates the two.

“This digital world is one of the most exciting times,” said SKF president John Schmidt, during the event’s opening message. “Whether connected or handheld digital devices…all of these tools have expanded our competency and allow us to impact the performance of rotating equipment.”

Schmidt credited digitally connected devices (via the industrial internet of things) for optimizing three main approaches to manufacturing and equipment maintenance: 1. Life modeling (predicting the life of a bearing); 2. Condition monitoring (detecting and predicting equipment faults); 3. Data analytics (examining information and forming conclusions).

“With the fourth addition of connected devices, we can now work to a scale that was previously unimaginable,” he said.

John Chioffe, SKF’s director of business intelligence, agreed. “Data drives decision-making or at least it should, and most senior leaders understand that data is a core business asset. They also understand that the use of data and analytics is important in making better business decisions,” he said during his presentation at the press event.

This is good news but Chioffe also pointed out that there is a “common problem” in several industries. According to research group Mackenzie, fewer than 20% of organizations have maximized data analytics or scaled it for optimization.

“Certainly, nearly every application or business function has collected data and stored it in its own data repository and created its own data model. But this had led to huge data proliferation.” Chioffe explained that companies are typically collecting a vast amount of relevant industry data — but not sharing it. “This is leading to data silos.”

As a sidebar to Chioffe’s talk, a recent study by ONYX Insight serves as a case-in-point in the wind industry. The predictive analytics company found that access restrictions to wind-turbine performance data are preventing wind from reducing O&M costs — by up to 30%.

“In recent years, the industry has been gathering ever greater amounts of data, and greater processing power has allowed the industry to mine rich data streams faster and more accurately,” said ONYX Insight CEO, Bruce Hall, in a related press statement. “However, restricted data access stops us from gaining these insights – and realizing their economic benefits.”

Chioffe discussed a similar narrative during his talk. “Now companies are starting to realize that to survive in their competitive market, they have to unify and democratize their data,” he said. “What I mean by this is to unify the data and bring it all together and then to democratize it and make it accessible to everyone.”

The real value of accessing this data comes from the insights it could provide industries. “The benefit is when the data can be correlated with information that is actionable, easy-to-use, and easily accessible,” said Chioffe.

One question to ask yourself or your company: “Are you using your data strategically?”

According to Chioffe, it’s imperative to employ prescriptive or advanced data and not solely rely on description or historic analytics. “Descriptive analytics tells you what you already know…but you want to know what actions to take.” For wind, this could mean determining that a bearing is subject to micropitting before failure and having the maintenance plan in place. For SKF, this has meant modernizing the customer experience.

“We want to predict and reduce supply chain so that customers can have the right product at the right time, when they need it. We almost need to know what they need before they do, and without the right data we wouldn’t be able to do that,” said Chioffe. He said SKF also wants to help customers reduce operating costs and increase profitability. “The data is not just about us. It’s about helping our customers.”

He said SKF is actively educating people on what it means to be a data-driven culture and employing new resources, such as data scientists and visualization developers. “The new digital world is here and it’s important to advance with it.”

Effective use of data may lead to several benefits, including those listed above.

To help keep up, Chioffe provided a few data fundamentals.

1. Data is everywhere. There are few limits to what is trackable or scalable.
2. Understand the data landscape. This means planning a clear data strategy (knowing what data to look at, how to use it, and when). “Because of the sheer amount of data, you have to have a plan about how to use it wisely,” said Chioffe.
3. Institute a robust governance program. Conventionally, this goes to the IT department, said Chioffe. But he suggested governance belongs to those who have the knowledge and capability to understand and change the results — which may require different expertise than IT.
4. Re-evaluate data architecture. Technology is changing rapidly. It’s important to keep architecture current and updated.
5. Mobilize the organization. “This requires changing mindsets,” said Chioffe. “And educating employees about what it means to be a data-driven culture and how to think differently. It starts with senior management.” 

What’s new at SKF…

As part of its aim to help customers, SKF recently launched a Rotating Equipment Performance program, which maximizes machine performance and minimizes O&M costs. SKF works with clients to monitor equipment, detect and solve problems (using actionable data), maintain performance, and rebuild services. The aim is to optimize equipment and lower the overall cost of ownership.

SKF also offers SimPro Quick single-shaft bearing-simulation software, developed to quickly evaluate the design of bearing arrangements and their field performance based on relevant application requirements and conditions. The goal was to provide designers with more SKF engineering knowledge and autonomy to accelerate the design process and optimize the selection of appropriate bearings.

The post How SKF is letting data drive its decision-making appeared first on Windpower Engineering & Development.