Laser Cladding vs Thermal Spraying: What’s the difference?
Over the past few years, a growing number of companies that offer laser cladding strongly push, that laser cladding is superior to all thermal spray coatings. As an industry leader in thermal spray coatings, we wanted to show you how thermal spray can be the superior coating application for you.
Before we delve into the differences between thermal spraying and laser cladding, let's start with a brief explanation of these techniques.
Thermal Spraying:
Thermal spraying is a process used to apply a coating to the surface of a material, like metal, to protect it from wear, corrosion, or heat. Imagine spraying paint from a can, but instead of paint, you're using tiny melted particles of metal or ceramic. These particles are heated up (often by a flame or an electric arc) and then sprayed onto the surface, where they cool and form a protective layer.
Laser Cladding:
Laser cladding is a technique that uses a high-powered laser to melt a coating material and a thin layer of the surface it’s being applied to. The melted coating material, often a type of metal or alloy, fuses with the surface as the laser moves along. This creates a strong, well-bonded layer that can improve the surface's properties, like making it more resistant to wear or corrosion. Think of it like using a laser to weld a protective layer onto an object.
THERMAL SPRAY VS LASER CLADDING
| Thermal Spray | Laser Cladding |
|---|---|
| Very low heat input. No change of the substrate metallurgy. | Low heat input, but concentrated over a small substrate area that may cause an unfavourable, hard, metallurgical structure at the bond if untreated. Carbon containing materials are of particular concern, %C greater than 0.15%. |
| No pre-heating required. | Pre-heat required, and some materials (such as 4140) can be flame hardened. As such, correct heat application type must be ensured. |
| No post application heat treatment. | Post weld heat treatment (PWHT) to soften the bond in material with C>0.15%. This heat treatment affects the whole part, and the whole part is softened. Failure to PWHT may result in rapid service failures due to in-service cracking starting at the bond. |
| Greater wear resistance — up to 88% WC for greater wear resistance. | Lower wear resistance — up to 60% WC for wear resistance. |
| No distortion of part. | Distortion due to residual stresses from welding. Residual stresses may lead to component distortion and cracking. |
| Process independent of substrate material or component shape, which means .pProcedure is only dependent on coating material. | Laser is dependent on substrate material, substrate finish, and the shape of the component. As such, a new procedure is required for each coating and every substrate type. |
| Larger range of materials due to application method. | Limited product range since coating and substrate must be metallurgically compatible. |
| Able to apply metals, non-metals, cermets, and amorphous coatings. | Limited to compatible metals and cermets. |
| Able to apply to all metallic substrates. | Limited to weldable materials. Exclusions include many cast irons, precipitation hardened steels, and amorphous materials. |
| Fewer process variables that are easier to control. | Many variables that have significant effects on the final product, e.g., surface finish, interpass temperature, powder cut, lens cleanliness, variations in powder flow, reflections due to geometry changes, component temperature increase over time, necessity for extreme accuracy in robotic application, nozzle height, configuration of gas and powder outlets, etc. |
We’ve put this comparison together to help you make an informed decision about the right option for your components. In every instance, thermal spray comes out as the superior wear resistant product. Plus, it is typically cheaper than laser, without all the hassles of heat treatments and complicated weld procedures.
Even so, if you feel laser it the best option, ensure you ask for a qualified weld procedure that specifies both the substrate (and its preparation) and the coating. Ask about expected distortion levels, as well as potential residual stresses and what post weld heat treatments would be required to prevent failure in service. If your component is subject to cyclical loading, such as a rotating shaft, you may also want to confirm the laser procedure with fatigue testing.
Or alternatively, choose
thermal spray.
