APO-GEE, the Belgian deep-tech startup specializing in innovative ball bearing solutions, has successfully resolved the cage instability problem encountered by VEOWARE, a promising New Space company notably specializing in in-orbit motion control and satellite agility, and having developed an innovative Control Moment Gyroscope for small satellites.
The phenomenon of cage instability is a chaotic occurrence whereby the bearing cage suddenly acquires significant kinetic energy, leading to a whirl or hula hoop movement that causes vibrations. This can result in cage breakage, bearing seizure and system guidance failure. Although studied for over 50 years, this issue had not been fully modeled or resolved until recently, when APO-GEE tackled it with the Butterfly Cage.
Julien Demonty, Managing Director of VEOWARE, stated, « At the end of the product development and during the qualification test campaign, we noticed a weird noise randomly appearing from the flywheel. After long investigation, we suspected bearing cage activity. We were advised by ESA to contact APO-GEE to further investigate this issue. APO-GEE helped us confirm the root cause and propose a solution. Fortunately, we succeeded in pinpointing the issue during our qualification test campaign and not later as it could have degraded our product’s micro-vibration footprint. »
In space applications, instability issues are particularly critical due to significant technological, financial, and political stakes involved. If a bearing becomes unstable in a reaction wheel or gyroscope on a satellite or spacecraft, finding a solution is extremely challenging as replacement is often impossible. Over the past decades, many space missions have encountered major problems, with some even being aborted due to ball bearing issues.
The absence of a strong baseline for ensuring terrestrial qualification to guarantee proper ball bearing functionality in space further complicates matters.
The Solution: preventing cage instability and reducing vibrations!
Christophe Servais, CTO of APO-GEE, explained, “The cage instability problem is a chaotic phenomenon, which implies that it cannot be solved by purely computational methods or even AI. Today, this phenomenon remains poorly understood, and misconceptions about it are common. For example, one may think that the probability of the phenomenon triggering is thought to increase with speed, whereas, in reality, it can occur at all speeds. This also explains why existing ‘solutions’ are only partially effective or even entirely erroneous.”
APO-GEE’s success in solving the complex cage instability problem can be attributed to two main factors. The first reason lies in the fact that comprehensive understanding of the kinematics of the balls and cage dynamics has always been challenging, and accurately modeling them has proven elusive. However, APO-GEE can. Thanks to original tools, the startup has the unique ability to model and accurately predict the cause of all bearing misbehavior, regardless of operational conditions, where most current models and related tools rely on simplifying assumptions. This gives APO-GEE unique product development and application engineering capabilities.
The second reason lies in the R&D journey itself, and more specifically, its duration. Innovation in ball bearings has seen some beautiful progress, thanks to the invaluable contributions of intelligent individuals within various smart organizations. However, what truly distinguishes APO-GEE is the rare opportunity its founders had to enter deeply into a single subject for an extended period of more than a decade. This is exceptional, as in most organizational settings, time and resource constraints often prevent prolonged focus on a single research and development project. This long-term dedication to understanding the complexities of bearing physics has opened new possibilities for a remarkable advancement and breakthrough in the field: the Butterfly cage that prevents any instability from occurring in ball bearings. But it goes even further: the innovation also helps to reduce noise and vibration levels overall, at all speeds, without compromise! This advancement has been extensively proven and rigorously tested.
The company’s solution is perfectly compatible with the latest advances in materials science. Small and medium-sized batches can be produced and delivered in various materials, including composites and polymers such as PEEK or phenolic resin for instance. Additionally, APO-GEE has developed a unique methodology and tools based on the innovative concept of “Stability Maps” which accurately assess any cage’s sensitivity to instability. This methodology has been successfully employed on various aerospace and industrial projects.
A Game-Changing Technology Beyond Space Applications – the case of machine-tool spindles and beyond
While cage instability problems have been extensively documented in space applications, they are less recognized in other industrial sectors. However, these issues also significantly affect reliability and maintenance operations in many industrial applications.
Sébastien Assouad, CEO of APO-GEE, noted, « We have been in contact with several machine-tool spindle manufacturers, and all have confirmed a problem of ‘rattling noise’ that occurs unexpectedly and causes vibrations, even with new or relatively new bearings. Until now, the only solution available to these manufacturers was to replace the bearings. We deeply analyzed the problem and the bearings involved and demonstrated that it was a cage instability issue. Here too, the Butterfly Cage provides a definitive solution to the problem. We have seen that other applications, such as turbomolecular pumps or boat stabilizers for instance, may also suffer from similar problems under certain conditions. ».
APO-GEE: Future Development Projects and Challenges
Founded in 2022 with over a decade of research background, APO-GEE has made significant progress since commencing commercial activities. Supported by the European Space Agency (ESA) and specialized deep-tech investors, the company is well-positioned to make strategic development choices and continue its development.
Sébastien Assouad, CEO remarked, « The development possibilities are numerous. We started with very concrete issues encountered by the space industry, and in recent months, we see that opportunities are even greater in other industrial sectors. The case of machine-tool spindles is a perfect example. Let us also note that, beyond solving the cage instability issue, we pushed the developments on the cage even further and succeeded in reducing the microvibrations induced by the cage in the bearing. This represents a major advancement not only in space applications and ultra-high-precision machining, but also in addressing some new challenges in the defense and the automotive industry for example ».
The company also remains deeply rooted in innovation. It has thus developed the Cobweb Bearing. Initially designed for high-speed ball bearing applications, the Cobweb Bearing represents an innovation that offers perhaps the most accurate and precise functioning ever. It’s a true breakthrough in the bearing industry.
Christophe Servais, CTO of APO-GEE, stated, “For decades, designers of mechanisms were forced to accept unsatisfactory compromises to deal with high speed and combined loads, with consequences in terms of noise, vibrations, excessive heat, cage breaking, or bearing malfunctioning. Until today.” Initially developed to address issues encountered in rocket engine turbopump bearings, the Cobweb Bearing‘s scope can extend to turbochargers, machine tools, or medical applications.
What is APO-GEE’s biggest challenge? Sébastien Assouad, CEO of APO-GEE, said, “Our greatest challenge remains entrenched ideas, or the Not-Invented-Here Syndrome, which is normal when entering new markets with disruptive ideas. But things are changing! ESA believed in us and trusted us, and now others strong industrial players and customers do too. That’s what makes the adventure so exciting!“
For more information on APO-GEE, visit the website.
Contact:
Sébastien Assouad – CEO – [email protected]
Christophe Servais – CTO – [email protected]
