Ball screws are high‑precision linear motion systems that convert rotary motion into linear motion thanks to the continuous recirculation of balls inside a nut.
This mechanism drastically reduces friction compared to other threaded systems, ensuring high efficiency, positioning repeatability, and long operational life.
In the aerospace sector, ball screws are mainly used in fixed‑wing aircraft for actuating movable surfaces such as flaps and stabilizers; for the actuation of onboard satellite mechanisms, engines and launch vehicles; and in critical systems such as electromechanical brakes and thrust‑vector control actuators.
In this context, precision, reliability, and compatibility with extreme environments and stringent structural constraints are required.
Designing mechanical components for space applications involves extreme constraints in terms of weight, envelope, reliability, and behavior in hostile environments.
Ball screws intended for space missions must maintain full functionality in vacuum conditions, extreme thermal excursions (from –150 °C to +150 °C), exposure to ionizing radiation, and in the absence of conventional lubrication.
They must also withstand vibration and shock loads during launch and ensure consistent performance throughout the entire mission duration, with no possibility of maintenance or replacement.
The design of a ball screw for space use begins with the selection of low‑outgassing materials that are compatible with vacuum environments and capable of withstanding repeated thermal cycles.
Surface treatment of metallic components is crucial to reduce wear and improve tribological performance in the absence of atmosphere.
Recirculation systems must be optimized to avoid contamination build‑up areas and ensure continuity of motion.
Additionally, the choice of preload and dimensional tolerances must account for differential thermal expansion between screw and nut.
Lubrication, finally, is managed through solid lubricants or PFPE‑based lubricants specifically qualified for vacuum and radiation environments.
Every ball screw intended for space missions must undergo a rigorous qualification process compliant with ESA or NASA standards.
Tests include functional cycling in thermal‑vacuum chambers, shock and vibration testing, torque and friction measurements, and dimensional inspections using high‑precision systems.
Manufacturing processes must be traceable and certified, with non‑destructive testing (NDT) applied to welds and critical surfaces.
Final validation is completed with flight‑standard qualification, ensuring that each component can operate reliably under real mission conditions, in accordance with the highest standards required for the design of ball screws for space applications.