Cold Spray
Cold spray is a solid-state metal deposition process in which powder particles are accelerated by high-pressure gas to supersonic velocity and bond on impact without melting the feedstock. Unlike fusion welding or conventional thermal spray, it produces coatings, dimensional restoration, and additive build-up in CNC-assisted cells while preserving the substrate's original metallurgy and dimensional stability.
On the shop floor, cold spray is typically paired with CNC machining in a hybrid add-remove workflow. A worn area is prepped, then metal powder is accelerated through a high-pressure nozzle and deposited in layers to oversize the part. The CNC machine then re-machines the deposit back to final tolerance in the same cell. This approach restores diameters, contours, and corrosion-worn features without the heat-affected zone, distortion, or phase changes of fusion welding and thermal spray. Shaft repair, manifold and bracket restoration, feature build-up, and near-net additive repair all benefit when the substrate must retain original metallurgy and dimensional stability. Industrial systems include a high-pressure compressor, powder delivery and nozzle, robot motion, and powder recovery, with deposition executed layer-by-layer before finish machining. Because particles bond through kinetic energy and plastic deformation, the process suits heat-sensitive substrates and difficult-to-fuse metal combinations.
Does cold spray create a heat-affected zone?
No significant heat-affected zone forms because the powder remains solid throughout deposition. Thermal input is far lower than fusion-based repair, making the process suitable when melting, distortion, or metallurgical degradation must be avoided.
What are typical particle sizes and velocities in cold spray?
Published sources describe powders in the 1–50 µm or 5–100 µm range depending on the system. Particle and gas velocities are commonly in the 500–1500 m/s range, with production systems often operating around 600–1000 m/s particle speeds.
Is cold spray additive manufacturing or just coating?
Both. It is fundamentally a powder consolidation and thermal spray method, but when thickness is built into a freestanding feature or repaired geometry, it functions as additive manufacturing.