Additive manufacturing lets you build parts layer by layer using digital designs. A more specialised version of this is cold spray additive manufacturing (CSAM). This technique comes with advantages such as:
- Speed
- Mechanical Integrity
- Preservation of Material Properties
CSAM is different from other additive manufacturing processes since it doesn’t require heat to melt materials. Instead, it uses kinetic energy to deposit metal powders at high velocity onto surfaces. This creates parts that are as durable as they are versatile, and you’ll see them used in industries from aerospace to defence to automotive.
The Cold Spray Process: An Overview
CSAM is typically achieved with the help of a supersonic gas jet. The “cold” part in the name refers to the fact that the materials never reach their melting points. Instead, these particles undergo plastic deformation upon colliding with the surface, bonding tightly without ever melting.
This makes it a solid-state additive manufacturing process that both minimises heat-related distortion and retains the inherent properties of the material. Melting and solidification are key parts of more traditional additive manufacturing processes, but this leads to a host of problems, including:
- Thermal Stress
- Distortion
- Microstructure Changes in the Final Product
In contrast, cold spraying results in faster production times and superior mechanical properties in the finished product.
How Cold Spray Technology Works
Cold spray systems introduce a powder feedstock (typically metal or alloy powders) into a high-velocity gas stream. This gas gets pressurised and heated, where it reaches supersonic speeds as it shoots out of a specialised nozzle. Those powder particles continue to accelerate along this gas flow and impact the substrate surface at lightning-fast speeds.
The particles don’t melt but instead adhere through plastic deformation. The speed is so fast that it alters the material’s microstructure and mechanical properties, enhancing the density and bonding strength of the deposited layer.
Eventually, this layer-by-layer accumulation produces a solid part with little-to-no thermal distortion. Cold spraying, particularly with high-pressure cold spray systems, gives us dense, durable, and dimensionally accurate parts that can be used directly or machined for further precision.
Advantages of Cold Spray Additive Manufacturing
Cold spray additive manufacturing stands out the most in industries where durability and precision are essential:
- Heat-Free Application: Cold spraying doesn’t melt materials, significantly reducing thermal stress and preventing undesirable changes in the material’s microstructure. This preserves the material’s original strength, toughness, and resistance to corrosion.
Industry-leading speed
Build high-performance metal parts at 5-6kg per hour, competing directly with commercial, traditional manufacturing methods.
Minimal size constraints
Cold spray can build very large metal parts with minimal limitations, with systems designed for parts 3-9 metres in length or larger.
Near-net shape manufacturing
Build parts to near their final desired shape, saving up to 90% of machining waste and saving time and costs.
Multi-metal, seamless parts
Build single-piece parts seamlessly with multiple metals, from titanium, steel, copper, and much more.
Enhanced Mechanical Properties
Parts made through cold spray usually have mechanical properties superior to those made with traditional methods, including higher density and improved tensile strength. Unlike traditional methods, cold spray avoids thermal cycling, preserving the material’s structural integrity.
Tailor the manufacturing process, tailor the part
By manipulating the variables of cold spray, such as metal, gas pressure and temperature, certain mechanical properties can be achieved based on the part requirements, such as ductility, hardness, and so on. Importantly, these characteristics can be altered within the same part.
For example, a steel ballistics plate could feature a very hard strike face, while the rear portion of the plate could be made more ductile, while also featuring titanium for weight reduction.
Enhanced Mechanical Properties
Parts made through cold spray usually have mechanical properties superior to those made with traditional methods, including higher density and improved tensile strength. Unlike traditional methods, cold spray avoids thermal cycling, preserving the material’s structural integrity.
Fusion of Dissimilar Metals
Because the process doesn’t melt metals, those with different melting points can be fused together. This allows for leveraging the strengths of multiple metals within a single, seamless part, without joining or welding.
For instance, ballistics panels can combine steel and titanium, or aluminium can be applied to steel to remove and protect against corrosion.
Rapid Deposition and Scalability
Cold spray is a fast and scalable additive manufacturing process. It can be used to build large structures quickly, making it highly adaptable across various applications. For example, large pure titanium parts can be built at speeds of 5–6 kilograms per hour.
Large Scale
Cold spray doesn’t require an inert environment, unlike many melt-based methods. This allows for the production of large-scale parts without size limitations.
Minimal Waste
Because the powder particles are directly deposited onto the surface, there is minimal material waste, making cold spray technology environmentally and economically advantageous.
Compatibility with Diverse Materials
You can use cold spray with a wide range of materials, including:
- Commercially pure titanium and Ti-6Al-4V
- Steel and steel alloys
- Inconel 625 and 718
- Aluminium alloys including 6061 and 7075
- Silver, gold and other precious metals
- Tantalum and other refractive metals
- Tungsten alloys
- Magnesium alloys
- Invar36
- Certain ceramics
Applications of Cold Spray Additive Manufacturing
Cold spray is used to produce standalone parts, as well as for surface and coatings technology. This enhances mechanical properties and lifespan. For example:
Surface Coating and Repair
Cold spray systems are frequently used to apply protective coatings, enhancing wear resistance, corrosion resistance, and thermal conductivity. This makes them valuable in industries like oil and gas.
Additive Manufacturing and Component Building
Cold spray can fabricate entire components from scratch, offering a streamlined and cost-effective alternative to traditional methods like machining or welding.
Remanufacturing and Restoration
Cold spray can restore worn or damaged parts, adding material only where necessary and minimising waste.
Application-Specific Coatings
Cold spray systems can deposit custom material blends, achieving the exact properties needed for specialised applications.
Comparing Cold Spray to Other Additive Manufacturing Technologies
Unlike most additive manufacturing technologies, which use heat to build parts, cold spray eliminates heat, avoiding issues such as warping, shrinkage, and thermal distortion. This makes it ideal for materials prone to cracking under thermal stress.
The Future of Cold Spray Additive Manufacturing
The cold spray process continues to evolve, with advancements enhancing deposition speed, material compatibility, and precision. As adoption grows, its application range will expand, driven by innovations in powder particles, gas systems, and robotic integration.
Cold spray is set to complement and, in some cases, rival traditional manufacturing methods, offering efficiencies in producing durable, high-quality components with minimal waste.
For a more in-depth understanding, check one of the hundreds of journal articles written about cold spray.
