Cold Spray

The video shows how an aluminum shaft shoulder is coated with pure copper.

What is cold spray?

Cold Spray is an innovative thermal spray process. The technology enables the production of components and coatings without significant heat input, resulting in minimal thermal deformation and high bonding between the layers. Cold spray has become increasingly important in recent years and opens up new possibilities, particularly in additive manufacturing.

© Fraunhofer IPK
Manufacturing system in the coating booth: a cold gas gun on a robot system .

How does cold spray work?

In cold spray, solid powder particles are accelerated by a stream of carrier gas onto the surface of a substrate material. Due to the special nozzle geometry and the associated thermodynamic effects, the particles reach speeds of up to 1200 m/s and deform plastically upon impact with the surface. The deformation forms a high-density, firmly bonded layer of material on the substrate. Due to the low temperatures of the process the powder particles remain in a solid state throughout the entire process. This preserves the original properties such as the microstructure of the materials and avoids defects associated with melting and fusion, such as oxidation and thermally induced internal stresses.

Cold spray in additive manufacturing

Additive manufacturing processes involve applying material layer by layer in various ways to create physical objects from digital 3D models. Cold spray additive manufacturing (CSAM) complements this technology by enabling the production of complex, large-scale geometries with special properties.

© Fraunhofer IPK
Rotor of an electric motor with additively manufactured permanent magnet made of neodymium-iron-boron (NdFeB)

© Fraunhofer IPK
Additively manufactured, topology-optimized lightweight component produced with cold spray

© Fraunhofer IPK
Semi-finished product to produce round tensile testing specimen made of pure copper with a height of 80 mm

Advantages of cold spray

Low process temperatures: Prevents warping due to thermally induced internal stresses and changes in the material properties of temperature-sensitive materials.
High coating quality: The kinetic energy of the particles creates a coating with low porosity and high adhesion to the substrate surface.
Versatility: Various materials such as metals, metal matrix composites and polymers can be processed. In addition, the cold spray process can be used to join non-weldable material pairs, allowing for material combinations that were previously impossible.
Design freedom and complexity: As a robot-guided process, it is possible to manufacture large components with dimensions of more than two meters. The powerful control system, which can control a rotary tilt table in addition to the six robot axes, can produce components with complex geometries.
Efficiency: The cold spray process has one of the highest build-up rates compared to other additive manufacturing processes. Depending on the material, build-up rates of up to 12 kg/h can be achieved, while at the same time reaching an application efficiency of up to 99 percent.

Possible applications

Repair and remanufacturing: Worn parts can be repaired quickly and efficiently by applying material to their surface. Even materials that cannot be welded or are otherwise difficult to repair, such as magnesium and gray or white cast iron, can be repaired using the cold spray process.
Functionally integrated components: Cold spray can produce parts that combine different materials and material properties in a single component.
Lightweight construction: The process can be used to create lightweight yet rigid structures.