Laser Metal Deposition (LMD) / Laser Cladding
Laser cladding is a technology of adding one material to the surface of another, by feeding of a stream of metallic powder (or wire) into a melt pool, that is generated by a laser beam as it scans across the target surface, depositing a coating of the chosen material.
Process
Laser cladding, also known as Laser Metal Deposition (LMD) or Direct Energy Deposition (DED), uses metal alloy powders or metal wire to enhance the surfaces of metal components.
Laser Cladding process uses a laser beam to form a melt pool on a metallic substrate. Metal powder or metal wire is injected directly into the melt pool, and the deposited metal then cools in a controlled and consistent pattern, creating a full metallurgical bond with the substrate.
In laser cladding, the laser beam is de/focused on the workpiece with a selected spot size. The powder coating material is carried by an inert gas through a powder nozzle into the melt pool.
The laser optics and powder nozzle are moved across the workpiece surface to deposit single tracks, complete layers or even high-volume build-ups”.
This helps to achieve the following advantages:
- Low heat affected zone (HAZ).
- Low dilution with the substrate (around 5%), resulting in better coating properties.
- Metallurgical bonding, which leads to the highest impact resistance.
- Low heat input, resulting in negligible distortion.
- High process reliability and repeatability.
- High deposition efficiency by working with powder materials (80-95%).
- High variety of deposition options.
One of the recently very popular subvariant of the conventional Laser Cladding (Laser Metal Deposition) is an high-speed laser cladding technique, that are getting more attention of the industrial users in coating applications, because of the major reasons:r
- High-speed laser cladding provides higher processing efficiency.
- Higher processing precision.
- Lower future processing costs.
- Minimal quantity of heat input to the workpiece, which can decrease workpiece deformation, among other benefits.
Extreme High-speed Laser Application (EHLA) or High Speed Laser Cladding (HSLC) deposition process, is a novel coating process invented by the German Institute for Laser Technology „Fraunhofer ILT“ and has demonstrated potential to be disruptive in large scale coatings production, as a green technology, capable of high speed and high material efficiency and low energy consumption.
Advantages of EHLA / HSLC Process
- High efficiency and quick speed: Processing efficiency (1,5-3,0m2/h), line speed up to 300m/min, significantly improved cladding efficiency.
- Smooth cladding layer: After the cladding is finished, it may be immediately honed and polished without turning, resulting in significant material and processing cost savings.
- The cladding layer might vary, from quite thin to thicker: Thin cladding (0,2mm-0,3mm), medium cladding (0,3mm-1,5mm), and thick cladding (0,3mm-1,5mm) are all possible, thickness, and in some cases, multi-layer cladding may be achieved, which is convenient and quick.
- The heat input is low, and the workpiece does not distort easily: High-speed cladding has a low heat input to the workpiece, a low degree of thermal distortion of the workpiece, and it may be utilized to process thin-walled and tiny components.
- Slow dilution: The dilution rate may be adjusted to 3%, which helps to preserve the cladding coating’s high-quality performance.
- Non-ferrous metals that can be processed: It is highly ideal for non-ferrous metal research and analysis because it can accomplish surface strengthening of non-ferrous metal materials such as copper, aluminium, titanium, and so on.
- The power density of the laser welding joint is high: It is capable of cladding high melting point powder materials.
Energy conservation and environmental protection, with widespread application: During the high-speed cladding process, no waste nus products are formed, breaking the restrictions of several traditional cladding application technics (like SAW, HVOF, HVAF, etc.). It is widely marketed and used in a variety of applications. It is presently a viable and successful method of replacing electroplating.