ROCKET PROPULSION ENGINE: SINGLE-PIECE THRUST CHAMBER AND INJECTOR

The manufacture of rocket components requires careful consideration of multiple critical factors. Beyond the need for lightweight yet durable construction, materials must withstand extreme stresses and high temperatures. Additionally, the intricate geometries of these components make production costs significantly higher when relying solely on conventional manufacturing methods.

The engine, developed by CellCore and Nikon SLM Solutions, features a thrust chamber, the core element of a liquid-propellant engine. It consists of a combustion chamber wall, fuel inlet, and an injection head with an oxidant inlet. Inside the combustion chamber, a chemical reaction generates expanding gas, creating a powerful ejection force that produces the thrust necessary to propel the rocket. During this process, extreme temperatures develop within the chamber, requiring an efficient cooling system to prevent the chamber wall from overheating.

To achieve this, the liquid fuel (e.g., kerosene or hydrogen) is first circulated through cooling ducts in the combustion chamber wall before entering through the injection head, where it mixes with the oxidant and ignites—traditionally via a spark plug. In conventional designs, these cooling ducts are manually machined into a solid blank and sealed through multiple processing steps. However, with Selective Laser Melting (SLM®), the cooling system is directly integrated into the chamber’s design, allowing it to be manufactured as a single component in one seamless process.

Due to the engine’s complexity, the traditional manufacturing process is highly time-intensive, taking a minimum of six months to complete. By contrast, CellCore’s 3D-printed engine demonstrates the revolutionary potential of Nikon SLM® technology for the aerospace industry. Through additive manufacturing, the engine can be built in under five days, significantly reducing production time and costs while enhancing functional optimization.

Part: Monolithic Thrust Chamber
Industry: Aerospace
Material: IN718
Layer Thickness: 30 μm
Build Time: 3d 5h 34 min (full load, 1 piece)
System: SLM®280

INNOVATIONS WITH SELECTIVE LASER MELTING

The single-piece rocket propulsion engine, integrating both the injector and thrust chamber, consolidates numerous individual components into a single unit. This multi-functional, lightweight design is made possible exclusively through Selective Laser Melting (SLM). At the heart of the engine is CellCore’s advanced internal structure, which cannot be manufactured using traditional methods. This design not only enhances heat transport but also significantly improves the component’s structural stability.

CellCore’s innovative cooling design far outperforms conventional methods, such as right-angled, concentrically running cooling ducts. It achieves an optimized balance between stability and mass, while maintaining low flow resistance and a high reaction surface. This results in greater efficiency, integrated functionality, and reduced weight compared to traditionally manufactured components.

To bring this highly complex design to life, Nikon SLM Solutions collaborated closely with CellCore, optimizing the Selective Laser Melting process for success. The customer success team at Nikon SLM Solutions developed specialized parameters tailored to the component’s geometry, focusing on downskin optimization. After consultation with application engineers, an ideal build plate orientation was determined, and critical sections were identified for test builds to ensure a flawless manufacturing process. To meet the stringent material requirements of the aerospace industry, the engine was printed using nickel superalloy IN718 on the SLM®280 selective laser melting machine.

IN718 is a precipitation-hardening nickel-chromium alloy, known for its exceptional tensile strength, fatigue resistance, creep resistance, and fracture toughness at temperatures up to 700°C. This makes it an essential material for aircraft, gas turbines, and rocket propulsion engines. When conventionally machined, its extreme hardness leads to excessive tool wear, making fabrication difficult and costly. Additive manufacturing eliminates this challenge by directly melting the powder material into the final geometry, reducing waste and extending tool life.

Despite its highly intricate structure, post-processing is minimized, further reducing tool wear and processing costs. Nikon SLM Solutions’ advanced SLM® technology provides significant cost savings by eliminating expensive, time-consuming manufacturing steps while simplifying the engine’s structure. For aerospace companies, Selective Laser Melting unlocks new opportunities, enabling them to enhance rocket system functionality, maintain exceptional quality, achieve lightweighting, and drastically reduce development, testing, and production timeframes, ultimately strengthening their competitive position in the industry.

SUMMARY

• Simplified manufacturing: Minimal post- processing despite complex structure to avoid tooling wear when processing too difficult to machine nickel-based alloy (IN718)
• Innovation: Direct integration of multiple parts and internal features, e.g. internal ducts
• Improved function: Cooling due to innovative lattice structure, which also increases stability
• Efficiency: Minimization of individual process steps while combining multiple individual parts into one component; production time reduced from months to days
• Lightweight construction: Considerable weight reduction due to lattice structures

CELLCORE GMBH

CellCore is a start-up engineering firm from Berlin specializing in a new kind of engineering and design for components and products. Their bionic engineering draws on highly efficient and evolutionarily optimized natural structural principles and applies these to technology. In its role as a development partner, CellCore creates innovative solutions for individual applications and ideas when conventional approaches encounter dead ends. Their core expertise lies in calculating and constructing cellular structures that combine with form-optimized outer contours that are tailored and adjusted to the specific application.

Through the design of a thrust chamber for a rocket propulsion engine, CellCore demonstrates the advantages of the selective laser melting process and how they are used in the aerospace industry. Printed in a nickel-based superalloy, the monolithic component was created in collaboration with Nikon SLM Solutions.

OUR MISSION, TO EMPOWER YOURS

To learn more about how Nikon SLM Solutions can help you optimize your manufacturing processes, please contact our team.