Industrial professionals may be familiar with spraying technology, but have you heard of "internal bore thermal spraying"? This technology, hailed as the most advanced engine internal bore machining technology, is not only the core of Europe's leading cylinder liner-less technology but has also been quietly cultivated in the global high-end engine field for over 20 years. From supercar engines to aerospace power units, it has rewritten the industry standard for internal bore machining with its unique process logic. Today, we'll unveil the mystery of this cutting-edge technology.
1. Internal Bore Thermal Spraying
In simple terms, internal bore plasma spraying technology uses atmospheric plasma spraying to precisely coat specially formulated powdered materials onto the inner surface of the cylinder. By flexibly selecting spray powders with different properties, multiple goals can be achieved, including low friction, low fuel consumption, high wear resistance, and high corrosion resistance. It is an indispensable key link in the cylinder liner-less technology system. Unlike traditional cylinder liner machining processes, this technology eliminates the need for additional cylinder liners, directly preparing the coating on the inner bore of the cylinder block blank. This simplifies the production process and maximizes the synergistic performance of the substrate and coating. As a cutting-edge technology refined over many years in Europe, it has already achieved mature application in the global high-end equipment field: engines in supercars such as Bugatti, Porsche, and Aston Martin; powertrain systems in high-end models of Volkswagen and Audi; diesel engines in Scania trucks; and even ROTAX series aircraft engines and motorcycle engines from brands such as BMW and Yamaha all rely on this technology to ensure core performance. In addition, internal bore thermal spraying has another extremely valuable application scenario—the remanufacturing of cylinder liners for high-end used engines and high-end commercial vehicle diesel engines. Through this technology, the internal bore performance of old engines can be precisely repaired, and even performance upgrades can be achieved, significantly improving the engine's recycling rate, saving resources and reducing user costs.
2. Process Principle
The reason why internal bore thermal spraying has become a "standard feature" of high-end engines lies in the performance leap brought about by its unique process principle, mainly reflected in two key dimensions:
2.1. Porous Oil Storage Structure
After internal bore thermal spraying, the cylinder bore forms an open and dispersed porous surface after honing. These smooth, rounded micropores act like miniature oil reservoirs, reducing the exposed area of fuel between the combustion chamber and piston rings, and effectively mitigating the tangential force on the oil scraper rings. The ingenuity of this design lies in its ability to allow piston rings to enter a more fluid dynamic lubrication state, fundamentally reducing frictional resistance and component wear, thereby reducing fuel consumption and the possibility of blow-by. Even more noteworthy is that this special porous surface oil reservoir structure is completely different from the textured structure of flat-top honing processes—the latter being easily worn away during honing. The porous structure, however, "dynamically regenerates" with wear: as the coating thickness gradually decreases, new lubrication pores continuously appear on the coating surface, ensuring lubrication stability during long-term engine operation and achieving sustainable performance output.
2.2 Thin-Wall Coating Design
After precise honing, the coating thickness of the internal thermal spray coating can be stably controlled between 120-150 micrometers. Compared to traditional cast iron cylinder liners, this thin-walled coating represents a significant leap in heat transfer efficiency—heat generated within the cylinder bore can be transferred to the cylinder block more quickly and evenly, effectively preventing engine performance degradation caused by localized overheating. It also provides more reliable thermal management for high-load engine operation. This "thin and precise" design ensures both the structural strength and wear resistance of the coating without increasing the overall weight of the engine, perfectly aligning with the development trend of "lightweight and high efficiency" in high-end equipment.
3. Application Scenarios
The value of internal bore thermal spraying is not only reflected in the production of new engines but also plays an irreplaceable role in the remanufacturing of high-end engines: For high-end used engines, wear and corrosion of the cylinder bore are the core issues affecting performance recovery. Traditional repair methods often struggle to accurately restore the dimensional accuracy and surface properties of the bore, while internal bore thermal spraying technology, through customized powder formulations and precise coating preparation, can restore or even surpass the original performance of worn bores, giving old engines a "new lease on life." In the field of high-end commercial vehicle diesel engines, cylinder liners are vulnerable components, resulting in high replacement costs and long replacement cycles. Remanufacturing repair through internal bore thermal spraying can significantly reduce user maintenance costs, extend engine lifespan, and improve the operational efficiency of commercial vehicles, aligning with the industry development philosophy of "green manufacturing and circular economy."
4. Conclusion
Internal bore thermal spraying technology, with its unique cylinder liner-less design, porous oil storage structure, and efficient heat conduction advantages, has become a "performance core" in the high-end engine field. From over 20 years of technological accumulation overseas to its application in the domestic market, from supercars and aero engines to commercial vehicle remanufacturing, it has proven its technological value and application potential through practical performance. The core appeal of this technology lies in its ability to not only solve the pain points of "high friction, high fuel consumption, and poor heat conduction" in traditional internal bore machining, but also provide a new approach to the lightweight, high-efficiency, and sustainable development of engines. With the continuous pursuit of core technologies by the domestic manufacturing industry, internal bore thermal spraying is expected to become widespread in more high-end equipment fields, driving China's engine manufacturing and remanufacturing industry towards higher quality and higher efficiency. For companies and users who pursue ultimate performance, this "black technology hidden in the engine" is undoubtedly an important choice to enhance core competitiveness.
