Finding the Needle in the Haystack: Technical Cleanliness at INNIO Group

Technical Cleanliness: Analyzing Residual Dirt Particles

The INNIO Group, headquartered in Jenbach, Austria, develops and manufactures innovative systems for energy generation and compression. As the company's large engines become more powerful and individual components are subjected to increasing loads, INNIO Group introduced Technical Cleanliness standards in Jenbach 10 years ago. Since 2015, the ZEISS EVO scanning electron microscope has been used to determine the origin of critical residual dirt particles.

Christian Troger, Operation Quality Leader at INNIO in Jenbach, emphasizes, "Even a tiny metallic dirt particle can cause significant damage in our high-performance engines." For example, if metal particles the size of a grain of sand were present in the connecting rod bearing, they could cause the oil film in the bearing to break. Without sufficient lubrication, friction between the crankshaft and connecting rod bearing increases, leading to severe damage. Repairing such damage on an engine weighing approximately 91 tons, like the Jenbacher J920, with a crankshaft nearly 7 meters long and weighing 8.5 tons, would be extremely complex and costly. Furthermore, it would significantly delay engine delivery to the customer. The higher the power density of the engines, the more important Technical Cleanliness becomes.

Industry Pioneer

With its engines, Jenbacher offers generator sets as well as combined heat and power (CHP) and combined heat, power, and cooling (CHPC) plants in the power range of 250 KW to 10.4 MW. These can be operated with a variety of energy sources such as landfill gas, sewage gas, biomethane, or hydrogen, paving the way for customers to transition to Net Zero. More than 25,000 Jenbacher engines have been delivered to around 100 countries. The INNIO Group sets industry benchmarks in terms of performance and reliability of Jenbacher engines. Development continues, with significant implications for the components of Jenbacher engines. The increase in mechanical efficiency to well over 50 percent, along with fuel flexibility regarding methane number, hydrogen content, and biogas, leads to increased peak pressures and bearing loads, as well as higher thermal stress on the engines. This necessitates, among other things, the use of harder bearings and significantly tighter tolerances. This development increases the risk of oil film breakdown due to critical particles.

Martin Mühlbacher, Vice President Operations & Site Manager, states, "Technical cleanliness is of high importance in our production, which is why we test on the ZEISS EVO Mat 25, allowing us to meet technical specifications 100%. And our engines can run for a long time with the highest quality."

Christian Troger notes, "With the continuous development of our engines, the importance of technical cleanliness also increases." This is an insight that the INNIO Group recognized much earlier than many other companies. The industry seems to have woken up. "For several years now, more and more quality managers and technicians have been attending technical cleanliness conferences," Troger emphasizes.

New Standards for Manufacturing

With the decision to introduce Technical Cleanliness standards in 2012/2013, INNIO in Jenbach began a comprehensive change process. Inspired by the automotive industry's experiences and based on the VDA 19 guideline, the entire process was initially modeled, purity specifications for sensitive components were determined, and particularly critical areas in manufacturing were defined. According to Troger, this involved approximately 800 project modules. Instead of pursuing arbitrary maximum goals, the INNIO Group in Jenbach consistently focused on implementing what was necessary. And what that was, was not solely determined by quality assurance. "We tried to bring everyone along," recalls the quality assurance expert, "including management."

"Because technical cleanliness always involves a cost-benefit or risk assessment."

The INNIO Group has invested approximately 3 million Euros in measures and solutions for Technical Cleanliness. This included installing airlocks, redesigning workstations, enclosing specific areas, and changing cleaning specifications. For instance, the concrete floor in assembly is now cleaned wet daily. To analyze residual dirt on components, a laboratory was established with specially developed systems for flushing the ton-heavy components.

Furthermore, a vacuum cleaner with a specially designed cyclone filter was developed for analyzing and cleaning critical engine areas, and investments were made in microscopes for examining analysis filters with captured residual dirt particles. Because it was discovered over time that wooden pallets could not be cleaned and thus contaminated the cleaned components with metallic and non-metallic particles and fibers, a complete switch to plastic pallets was made. Additionally, a cleanliness plan was developed for each workstation, precisely defining which areas at the workstation must be cleaned and with what frequency. Suppliers also had to be trained accordingly. According to Troger, it took two to three years "until we had a good standard."

"To maintain this standard, the entire process from goods receipt through manufacturing to shipping is monitored with particle traps."

When a limit value violation is detected, the analysis filter with the particles is examined more closely.

These particle traps indicate the contamination level and potential limit value violations in critical areas. The ZEISS EVO scanning electron microscope plays a key role in discovering and eliminating potential contamination sources.

A Scanning Electron Microscope for Material Determination

To determine the material composition and thus the origin of particles with the ZEISS EVO, the particles must first be detached from the component. This process takes place at INNIO in Jenbach in the so-called TecSa laboratory. Residual dirt particles flushed from the components in special washing systems are collected on a filter. This filter is examined on-site with a light microscope. "By determining the number and size of particles, we already know whether limit values are exceeded and how good our processes are." Since components are classified into risk groups and corresponding cleanliness categories, it is precisely defined which particle size and frequency are critical. If, for example, a limit value violation is detected on a crankshaft, the analysis filter with the particles is examined more closely, specifically with a scanning electron microscope.

"Initially, this analysis was performed by external service providers. But that took three weeks or longer, which was too long for INNIO's quality assurance."

Moreover, involving external parties complicated communication and thus the rapid detection of potential contamination sources. In 2015, the company therefore decided to invest in its own scanning electron microscope (SEM). The ZEISS EVO SEM works with the ZEISS Smart Particle Investigator software for particle analysis and classification, which complies with current ISO and VDA standards for Technical Cleanliness. The software encompasses all aspects of SEM control, image processing, and elemental analysis in a single application. And because the system performs particle analyses automatically, it can operate continuously and unattended, which also simplifies the work for Johannes Bachmann, the material analysis expert at INNIO in Jenbach.

"When he receives a filter for examination, he just needs to insert it into the device and can view the results after one or two hours."

Bachmann and Troger agree: "With ZEISS EVO MA 25, we find the needle in the haystack."

The ZEISS EVO SEM operates with the ZEISS Smart Particle Investigator (SmartPI) software for particle analysis and classification.

"ZEISS SmartPI encompasses all aspects of SEM control, image processing, and elemental analysis in a single application. And because the system performs particle analyses automatically, it can operate continuously and unattended."

In addition to structure and morphology, Bachmann can then see on the microscope's connected screen which chemical elements the particles consist of. To obtain this information, primary electron beams are directed onto the sample in the microscope. This causes the electrons in the atomic shell to emit X-ray radiation. Since the spectrum of radiation is characteristic for each element, the composition of the particles can be precisely determined using EDX analysis (energy-dispersive X-ray spectroscopy). Bachmann, who knows exactly which materials are used at the site, uses this information to identify the origin of the particles.

Stable Processes for Years

Ten years ago, when Jenbacher introduced Technical Cleanliness standards and redefined processes, Bachmann analyzed at least 20 filters per week. "Today, only a few filters per week need to be routinely examined."

However, even though the processes at INNIO in Jenbach run very stably, no one there can or wants to do without the scanning electron microscope. Bachmann and Troger agree: "With ZEISS EVO MA 25, we find the needle in the haystack." For example, if the analysis shows that a potentially dangerous particle consists of silicon, then according to Troger, there is a high probability that sluice gates may have been open and sand particles contaminated the component.

"Without the chemical analysis of the particle with the SEM, we would only know that we have a problem, but we wouldn't know where to start making improvements," emphasizes Troger.

Knowing relatively precisely where a particle comes from helps Troger and his team to re-sensitize colleagues to the issue of Technical Cleanliness or to initiate measures such as modifications. He encounters few acceptance problems. "At INNIO in Jenbach, the quality assurance department is not seen as the police or an unwelcome supervisor, but as an entity that supports on-site efforts to avoid errors before they occur and to implement improvements." And in his opinion, this has a lot to do "with the introduction of standards for Technical Cleanliness."

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