What Is Laser Cladding？
Laser cladding, also known as laser metal deposition, is a process for depositing one material on top of another. A stream of metallic powder or wire is fed into a melt pool formed by a laser beam as it scans across the target surface, producing a coating of the desired material.
The laser cladding method improves the surface properties of a part, such as wear resistance, and allows for the restoration of damaged or worn surfaces. One of the most accurate welding procedures is used to create this mechanical link between the base material and the layer.
Why is laser cladding an important manufacturing technology today?
By producing protective layers against wear and corrosion, laser cladding improves the performance of industrial items. Engineers may design parts with generic base metal alloys, which helps preserve natural resources. The component is then locally laser clad with a high alloyed material to provide the appropriate performance characteristics.
Laser cladding is also a method that is used to restore and remanufacture high-value components into their original shape. In addition to just fixing the shape of a part, choosing an additive material with superior wear characteristics than the original component improves service life and performance.
Arc Welding Thermal Spray Hard-Chrome Plating Laser Cladding
Heat Input High Low N/A (chemical process) Low
Dilution Rate 10 – 40% N/A(mechanical bonding) No metallurgical bond <5%
Hardness (HV) Relatively Low <1000 800 – 1000 >1000
Distortion High Low N/A Low
Heat Affected Zone Large and wide Low N/A Low
Quality Less durable Full of pores and less durable Prone to chipping and delamination Highly dense and Long life
Pre/Post Treatments Many Many Many Few
Automation Difficult Difficult Difficult Easy
Coat Thickness >0.020” 0.020” – 0.040” 0.002” – 0.006” >0.020”
Advantages Of Laser Cladding
When compared to traditional coating methods, laser cladding has various benefits. The benefits of laser cladding include higher quality coating material (including high bond strength and integrity) with less distortion and dilution, as well as improved surface quality. These benefits include:
⦁ low laser exposure duration and depth
⦁ layer and basic material metallurgical relationship
⦁ Thermal spray coatings are less durable than layers.
⦁ good surface quality and little warpage, with virtually no post-processing required
⦁ High energy economy, quick laser cladding process duration
⦁ Can be utilized with a wide range of materials as both the substrate and the layer, including custom alloys or
metal matrix composite (MMC) designs.
⦁ Within the deposits, there is little to no porosity (>99.9% density).
⦁ A narrow heat affected zone (EHLA as low as 10m) derives from a relatively low heat input.
⦁ The necessity for corrective machining is reduced when the substrate has little deformation.
Laser Cladding Classifications
There are many variations of laser cladding and laser cladding technology.
The powder is supplied into the path of the focussed laser beam above the substrate during the EHLA process. This ensures that the deposited material is already molten before making contact with the substrate; however, a very shallow melt pool remains on the substrate, allowing the deposited material to cool and solidify in contact with the underlying material, reducing the amount of heat reaching the component below as well as the depth of the dilution and heat effects.
This tiny dilution allows for the production of significantly thinner coatings (20-300m) that attain the necessary chemistry within 5-10m. This is also the foundation of EHLA’s high traversal speeds, which may surpass 100m/min.
Laser Cladding Target Materials
Laser cladding is possible with a range of metals, including:
Target Material Typical Hardness (HV) Thermal Stability (°C) Application
High Strength Steels (M2, H13) 550 – 650 450 – 500 Tool repair
Rockit™ 900 – 1100 – Excellent substitution for hard chrome, high abrasion resistance at ambient temperature
SS309, SS316L 250 – 300 – Used as root layer/build up, relatively good general corrosion resistance
SS420, SS431 550 – 600 500 – 550 Reasonable wear resistance
Stellite-6 550 – 600 500 – 550 Excellent galling, wear, erosion, and cavitation protection over a wide temperature range
Stellite-21 400 – 450 500 – 550 Superior thermal and mechanical shock resistance, relatively high resistance to galling and cavitation
Inconel-625 250 – 300 900 – 1000 Applied in extremely high corrosive environments, used as buffer layer
Inconel-718 400 – 450 600 – 650 Age hardenable, high temperature stability and corrosion protection, ideal for hot forging punch
NiCrSiB-65%WC 1500 – 2500 600 – 650 Extremely high abrasion/erosion resistance and excellent for part-to-part sliding wear due to relatively low friction coefficient
Colmonoy 69 (NiCrMoCu) 600 – 650 500 – 550 Excellent resistance to aluminum liquid erosion used in high pressure die cast
Ni80Cr20 300 – 350 1000 – 1100 Hot oxidation resistance
Aluminum-Bronze 200 – 300 350 – 400 Excellent galling resistance for cold forming tolls, good general corrosion resistance
Because of the variety of materials available, laser cladding may be utilized for a wide range of industrial applications, including quick manufacturing, component repair, and surface improvement. Tungsten carbide, for example, in an MMC, provides durability, making it perfect for coating applications requiring exceptional wear resistance.
Application Of Laser Cladding
Laser cladding is useful for a wide range of industrial applications. These uses range from agriculture and aerospace to drilling, mining, and power generation.
⦁ Flanges
⦁ Seats
⦁ Wear Sleeves
⦁ Pumps
⦁ Glass Molds
⦁ Seal/Bearing Journals
⦁ Impellers
⦁ Rotor Shafts
⦁ Pump Shafts
⦁ Compressor Wheels
⦁ Gearbox Housing
⦁ Propeller Shafts
⦁ Exhaust Valves
⦁ Rolls
⦁ Crank Shafts
⦁ Engine Components
⦁ Mandrels
Drilling tools
High-performance drilling instruments are required for the development of oil and gas reserves. These are subjected to extreme stress and would not have extended lifespans if not protected against wear. That is why, for some time now, special coatings, which are increasingly being achieved with laser coating technology, have become the norm.
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Coating of hydraulic cylinders for the mining industry
Laser coating of hydraulic cylinders in technological mining operations such as coal extraction is a rising business. The cylinder’s coating corrodes fast in the local climate, resulting in leaks, thus a replacement or fresh coating will be required.
Until recently, chromium plating was the dominant approach, but laser coatings will gradually replace it because of their greater endurance. The particular improvement in durability cannot yet be defined, although current data reveal a higher than 100% increase in lifespan.
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Cutting Tools
Layers of laser clad materials can be utilized to protect saw blades, counter blades, disc harrows, and other cutting instruments from wear and corrosion while also offering enhanced cutting properties. Because of the lack of distortion in this technique, these tools remain straight while variable coating thicknesses may be obtained to meet needs. These coated tools may be used in a variety of industries, including construction and agriculture.
Proven Solution for Hot Mill Rolls used in Steel Making Industry
Rolling steel is a procedure that pushes the performance boundaries of the rolling equipment’s components. Roller and other component failures can be caused by abrasion wear, heat stress, and galling, resulting in downtime and quality concerns. Because of the wide temperature range, a high hardness, low friction solution is required.
Haitian Laser Machinery provides a tried-and-true solution for increasing the service life of hot mill rollers. Customers who have used our laser cladded carbide-based overlays have experienced a 6x increase in service life when compared to thermal spray or arc welding, resulting in decreased operating costs and downtime.
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Bottom Punch/Magnet Dies
When producing magnets for motors, the magnet material is blended in a slurry and placed in a die. The slurry is then forced into the magnet die, forcing all of the water/contaminants out. These punches must have non-magnetic tips to avoid interfering with the polarity of the magnet. Furthermore, the dies are vulnerable to significant metal-to-metal wear.
Stellite 6 was traditionally applied to the top surface using GTAW. The dilution line between the base material (W2 steel) and the substrate (Stellite 6) was, however, choppy, and the manual procedure was time intensive (about 1 hour each punch).
To boost efficiency, HaiTian developed an automated approach. A coaxial powder feed laser head was employed in the solution, and bespoke programming was used to map the clad/layer routes.
HaiTian was able to construct a Stellite 6 buildup with a very clear dilution line between the parent and clad material, as well as a cladding in 15-20 minutes rather than 1 hour. As a result, this automated approach significantly increased quality and efficiency.
Wind Turbine Centrifuge Hubs/Shafts
Wind turbine hubs and shafts wear owing to load fluctuation caused by changes in wind speed/intensity. Because of this wear, gearboxes might break early, resulting in expensive replacement costs.
HaiTian used laser cladding on worn hubs, journals, and shafts before machining them to original design specifications. Stainless steels (410 SS, 420 SS, 440 SS) were used as base materials. 420 stainless steel was used as the primary cladding material. Controlling the preheat and process conditions carefully guaranteed that the clad material was defect-free and had similar/improved characteristics to the base material.
Steel Mill Rods
Steel mill rods are components that are frequently worn. Typically, the wear is minimal yet sufficient to render the rod unusable. IBC Coatings Technologies coat worn rods with lasers. The base material was a high strength steel (4140), and the overlay was 431SS martensitic stainless steel to increase the wear resistance of the substrate.
What Type of Laser Is Used in Laser Cladding?
1. Fiber Lasers
Fiber lasers, which use optical fibers to create laser beams, are well-known for their efficiency and dependability.
2. Diode Lasers
Diode lasers are a type of laser that produces laser radiation via a semiconductor. Diode lasers, which vary in wavelength, power, and fiber type, are used in two types of prostatectomy procedures
3. CO2 Lasers
Carbon dioxide lasers, often known as CO2 lasers, generate laser beams using a gas mixture and are ideal for cladding greater regions.
4. Nd:YAG Lasers
Solid-state crystals are used to create laser beams in neodymium-doped yttrium aluminum garnet lasers. They are adaptable to a variety of cladding applications.
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