Welding unseated – cold spray technology a cool new contender for repair.
Welding has long been the go-to method for repairs and restoration of metal parts. Although it’s a well-established and great method for joining metals, when it comes to repair, welding may not always be the most suitable solution. Unfortunately, with limited alternatives available, it has often been the common or default choice. However, a new technology is now emerging that promises to revolutionise the repair process and offer a more versatile and efficient solution: low-pressure cold spray technology.
Cold spray – also known as supersonic particle deposition – is a groundbreaking technology for repairing geometries and applying functional coatings. Unlike welding, which involves high temperatures and can result in distortion, residual stress, and damage to surrounding materials, cold spray operates without the need for extreme heat. Instead, it propels metal particles at supersonic speeds onto metal surfaces. As they collide, the kinetic energy of the particles causes them to deform and interlock with the metal surface, creating a strong, metallurgically bonded coating.
When it comes to repair and maintenance, the advantages of low-pressure cold spray over conventional welding are numerous. Firstly, the absence of high temperatures during the cold spray process eliminates the risk of distortion, annealing, and warping, saving more parts from damage. This characteristic is particularly beneficial for intricate and heat-sensitive components, such as crank cases, tooling such as dies, or where precise heat management is crucial.
Secondly, cold spray technology offers superior material compatibility, making it possible to repair and restore a wide range of metals. Unlike welding, which is often limited to joining similar metals, the cold spray system can utilise dissimilar metals such as nickel for repairing cast iron parts or aluminium for repairing steel structures and protecting them from corrosion.
In welding, the joining of metals relies on melting the base metals and adding a filler material that is compatible with them. The success of the weld largely depends on the metallurgical compatibility between the base metals and the filler material. If the metals being joined have significantly different compositions, properties, or melting points, achieving a strong and durable weld can be challenging or even impossible. Welding dissimilar metals often requires specialised techniques, such as the use of intermediate layers or interlayers, to promote bonding and prevent the formation of brittle intermetallic compounds.
On the other hand, cold spray technology offers a distinct advantage when it comes to joining dissimilar metals. In the cold spray process, metal particles are accelerated to supersonic speeds and impact the surface of the substrate material. These particles undergo plastic deformation upon impact, causing them to interlock and form a strong bond with the substrate. Unlike welding, cold spray does not rely on melting the base metals or using a filler material.
Perhaps the most promising aspect of cold spray technology is its ability to restore worn or damaged parts without compromising their original properties. By selectively depositing material only where needed, cold spray extends the lifespan of components, reducing the need for costly replacements. This feature presents significant cost savings for industries that heavily rely on maintenance and repair operations, such as oil and gas, mining, and marine.
One company commercialising cold spray is called Titomic, located in Melbourne. Titomic is bringing cold spray technology to the market, and is focused on adding value to machine shops, engineering firms, and maintenance firms alike.
“Welding is sometimes used where it shouldn’t be, as welding is often the best – sometimes only – solution available. We’ve spoken to many engineering shops who’ve gone to repair parts with welding, whether it’s crank cases, shafts, or bearings, only for them to spend time welding which might lead to cracks. As well as having to ditch the part, they’ve spent the time welding too,” said Dominic Parsonson from Titomic.
This emerging technology represents a potential shift in the field of metal part repair and restoration. With its ability to overcome the limitations of welding, it offers a more versatile, efficient, and cost-effective solution. By eliminating distortion, offering superior material compatibility, and extending the lifespan of components, cold spray technology is set to transform the way a range of industries approach repairs. As this innovative technology continues to evolve, it opens new possibilities and paves the way for a future where metal part repair becomes faster, more precise, and more economical than ever before.
