3D Printing for
Aerospace

Since 2023, CADDent has been a manufacturing service provider for the German Aerospace Center (DLR) for development and subsequently manufacturing small series parts for the measurement and sensor technology group of the Flight Experiments facility. This PT100 sensor is required for flight experiments with the "HALO" aircraft (High Altitude and Long Range Research Aircraft).

A special feature of this PT100 sensor developed for the aerospace industry is that the sensor head was made from zirconia using ceramic 3D printing. Thanks to additive manufacturing, it was possible to reduce the wall thickness of the sensor to just 0.3 mm in the head area and 0.5 mm in the remaining area. A 0.025 mm thin platinum wire was then wound around the head area and soldered to the copper wire.

This temperature sensor is partly made of platinum (Pt) and has a resistance of 100 ohms (Ω) at 0 °C. Through intensive research and development efforts, it was made possible to adjust the design and optimize the topology of the sensor.

The PT100 sensor benefits from the outstanding material properties of zirconia, such as very low thermal conductivity (2.5 - 3.0 W/m*K) and extremely high temperature resistance. In addition, the sensor connector is made of alumina and the connection is made of cobalt-chrome using 3D printing technology.

RF filters are crucial electronic circuits that enhance signal quality and minimize interference in communication systems like satellite communication, radar, and avionics. Ceramic 3D printing allows for the creation of highly-engineered resonators with a wide range of shapes, orders, and bandwidths that can be incorporated into a single component, optimizing performance, reliability, and durability.

Such RF filters play a critical role in ensuring reliable and accurate communications in high-frequency bands. Due to the harsh environmental conditions that they must withstand, these filters have to be highly performing and meet stringent reliability and performance requirements. The desirable material properties of ceramics make them perfectly suited to meet these requirements, securing longevity and excellent stability over temperature and time while also easily enabling the miniaturization of these filters to reduce weight – a successful key formula in aerospace applications.

To keep track with the development of ever more efficient rocket engines, nozzle designs have also undergone a significant evolution. In contrast to conventional bell-like nozzle designs, the aerospike nozzle uses a spike-shaped body to direct gas flow. This unique open geometry enables passive pressure adaption to the ambient air. Thus, aerospike nozzles always operate under optimal exhaust conditions.

Modern 3D printing methods now allow manufacturing complex structures which are necessary for cooling within the nozzle. To meet further thermal control requirements, the LCM process offers a method to take advantage of the excellent thermal properties of ceramics, such as those of silicon nitride. This new promising method raises high hopes for laying the cornerstone of future propulsion technology.

Increasingly more stringent requirements for environmentally friendly and fuel-efficient aircraft engines call for more innovative turbines, which naturally require greatly improved cooling. With Lithoz's LCM technology, such functional and efficient components can finally be produced.

In addition to drastically reducing development time and thus speeding up time-to-market, it is possible to enable ever shorter development cycles, as the 3D printing of complex designed ceramic cores eliminates the need for expensive molds and lengthy changeovers. This efficiency makes LCM the perfect choice when it comes to producing innovative cast cores for the aerospace industry.

The requirements for producing new designs of multi-bladed, complex and narrow cores go far beyond the limits of known conventional. The high-precision CeraFab 3D printing systems offer a tool-free solution that, thanks to the design freedom of additive manufacturing, enables the production of previously unachievable complex designs.

Lithoz's LCM technology can produce casting cores up to 500 mm in size. Lithoz offers a reliable, scalable and efficient solution that can perfectly map all requirements from prototyping to the production of large cores for industrial gas turbines.

These multi-layered casting cores feature innovative, complex inner structures for optimized heat management. Inspired by organic patterns found in nature, the forms are mathematically generated to deduct heat in the most efficient way by delivering the biggest possible surface area. These structures cannot be realized by traditional investment casting methods and were instead achieved using LCM technology at the IKTS Fraunhofer Institute in Dresden. To avoid mass piling, casting cores on average have a wall thickness of 1.5 – 2 mm. The 3D-printed component shown here has a wall thickness of < 1mm.

Printed with LithaCore material, these multi-layered components will show significant performance improvement even under extreme chemical and thermal conditions. They open up completely new opportunities of realizing highly intricate 3D-printed heat exchanger structures to be employed in traditional investment casting – all thanks to the unique possibilities created by our ultra-precise LCM technology.