What Is Laser Cladding？
Laser metal deposition, commonly referred to as laser cladding, involves the deposition of one material onto another surface. This is achieved by introducing a metallic powder or wire into a melt pool generated by a scanning laser beam. The result is a coating of the chosen material on the target surface. There are several laser cladding machines to perform these functions.
This method enhances the surface characteristics of a component, including increased wear resistance, and facilitates the repair of damaged or worn surfaces. The process employs a highly precise welding technique to establish a robust mechanical connection between the base material and the newly deposited layer.
What makes laser cladding a crucial manufacturing technology in the contemporary landscape?
Laser cladding plays a pivotal role in enhancing the performance of industrial assets by creating protective layers that guard against wear and corrosion. Engineers have the flexibility to design components using generic base metal alloys, promoting the conservation of natural resources. Subsequently, specific areas of the component can be selectively laser clad with high-alloyed materials to impart the desired performance characteristics.
Moreover, laser cladding serves as a valuable method for restoring and remanufacturing high-value components to their original specifications. Beyond simply restoring the shape of a part, the use of additive materials with superior wear resistance compared to the original component contributes to prolonged service life and enhanced overall performance.
Advantages Of Laser Cladding
In comparison to traditional coating techniques, laser cladding offers numerous advantages. These include the use of higher quality coating materials with superior bond strength and integrity, resulting in less distortion and dilution, as well as enhanced surface quality. The specific benefits encompass:
- Reduced laser exposure duration and depth.
- Establishment of a favorable metallurgical relationship between the layer and the base material.
- Enhanced durability compared to thermal spray coatings.
- Achieves good surface quality with minimal warpage, often requiring no additional post-processing.
- High energy efficiency and a rapid laser cladding process.
- Compatibility with a diverse range of materials for both substrate and layer, including custom alloys and metal matrix composite (MMC) designs.
- Minimal porosity within the deposits, exceeding 99.9% density.
- Formation of a narrow heat-affected zone (EHLA as low as 10m) due to relatively low heat input.
- Reduced need for corrective machining when the substrate experiences minimal deformation.
Classification of Laser Cladding
There are numerous iterations of laser cladding and its associated technology.
In the EHLA (Extreme High-Speed Laser Cladding) process, the powder is introduced into the focused laser beam’s path above the substrate. This ensures that the deposited material is molten before it comes into contact with the substrate. However, a very shallow melt pool is retained on the substrate, enabling the deposited material to cool and solidify while in contact with the underlying material. This minimizes the amount of heat transferred to the component beneath and reduces the depth of dilution and heat effects.
The limited dilution permits the creation of notably thinner coatings (20-300m) that achieve the required chemistry within 5-10m. This characteristic forms the basis for EHLA’s ability to achieve high traversal speeds, often exceeding 100m/min.
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
Efficient drilling instruments play a crucial role in unlocking oil and gas reserves. Given the harsh conditions they face, these tools would have limited lifespans without proper protection against wear. Consequently, the adoption of special coatings, increasingly facilitated by laser coating technology, has become a standard practice in the industry.
Application of protective coatings on hydraulic cylinders for the mining sector.
The utilization of laser coating technology for hydraulic cylinders in technological mining endeavors, such as coal extraction, is an emerging industry. The cylinders’ coatings deteriorate swiftly in the regional climate, leading to leaks and necessitating either replacement or recoating. Traditionally, chromium plating dominated this domain, but laser coatings are steadily supplanting it due to their superior durability. While the precise enhancement in longevity is not yet precisely quantified, current data indicate a lifespan increase exceeding 100%.
Cutting Tools
Utilizing layers of laser-clad materials proves effective in safeguarding saw blades, counter blades, disc harrows, and various cutting tools against wear and corrosion. This approach not only provides superior cutting properties but also ensures that the tools remain straight due to minimal distortion during the process. Moreover, the technique allows for variable coating thicknesses to cater to specific requirements. These coated tools find applications across diverse industries, including construction and agriculture.
Proven Solution for Hot Mill Rolls in the Steel Making Industry
The process of rolling steel places significant demands on the components of rolling equipment, pushing their performance limits. Failures in rollers and other components can occur due to abrasion wear, heat stress, and galling, leading to downtime and quality issues. Given the wide temperature range involved, a solution with high hardness and low friction is essential.
Haitian Laser Machinery offers a reliable solution to enhance the lifespan of hot mill rollers. Customers adopting our laser-cladded carbide-based overlays have witnessed a remarkable 6x increase in service life compared to traditional methods like thermal spray or arc welding. This results in reduced operating costs and minimized downtime.
Bottom Punch/Magnet Dies
In the production of magnets for motors, the magnet material is mixed into a slurry and introduced into a die. Subsequently, the slurry is compelled into the magnet die to expel any water or contaminants. It is crucial for these punches to feature non-magnetic tips to prevent interference with the magnet’s polarity. Additionally, the dies are susceptible to substantial metal-to-metal wear.
Traditionally, Stellite 6 was applied to the die’s top surface using GTAW (Gas Tungsten Arc Welding). However, the dilution line between the base material (W2 steel) and the substrate (Stellite 6) exhibited irregularities, and the manual process was time-consuming, taking approximately one hour for each punch.
To enhance efficiency, HaiTian devised an automated solution. This involved utilizing a coaxial powder feed laser head and custom programming to map the clad/layer routes. With this automated process, HaiTian achieved a Stellite 6 buildup with a well-defined dilution line between the parent and clad material, completing the cladding in 15-20 minutes instead of one hour. Consequently, this automated approach significantly improved both quality and efficiency.
Wind Turbine Centrifuge Hubs/Shafts
The wear and tear experienced by wind turbine hubs and shafts are attributed to the varying loads caused by fluctuations in wind speed and intensity. This wear can lead to premature gearbox failure, incurring substantial replacement costs.
HaiTian addresses this issue by employing laser cladding on worn hubs, journals, and shafts, followed by machining to restore them to their original design specifications. The base materials utilized include stainless steels (410 SS, 420 SS, 440 SS), with 420 stainless steel serving as the primary cladding material. Careful control of preheating and process conditions ensures that the clad material is free from defects and possesses characteristics similar to or improved from the base material.
Steel Mill Rods
Rods in steel mills often undergo wear, with wear levels that, while generally minimal, can render the rod unusable. IBC Coatings Technologies addresses this by employing laser coating on worn rods. The base material utilized is high-strength steel (4140), and an overlay of 431SS martensitic stainless steel is applied to enhance the wear resistance of the substrate.
Types of Lasers Utilized in Laser Cladding
1. Fiber Lasers
- Fiber lasers utilize optical fibers to generate laser beams, renowned for their efficiency and reliability in laser cladding applications.
2. Diode Lasers
- Diode lasers, employing semiconductor technology, produce laser radiation. These lasers, with variations in wavelength, power, and fiber type, find application in diverse laser cladding procedures, including certain types of prostatectomy.
3. CO2 Lasers
- Carbon dioxide lasers, often referred to as CO2 lasers, generate laser beams through a gas mixture. They are particularly suited for cladding larger surface areas due to their characteristics.
4. Nd:YAG Lasers
- Neodymium-doped yttrium aluminum garnet lasers use solid-state crystals to produce laser beams. Their adaptability makes them suitable for various laser cladding applications.
- Laser Hardening
- laser hardening is a precision surface treatment method that boosts the hardness and wear resistance of metals. By focusing a high-intensity laser beam on specific areas, rapid heating and cooling transform the material’s microstructure, increasing hardness. This targeted approach minimizes distortion and thermal damage, making it ideal for applications like gears and cutting tools in industries such as automotive and aerospace. The process ensures durable and wear-resistant components, enhancing overall product performance and longevity.
- Laser Hardening Machine
- A laser hardening machine is a specialized tool designed for the precise application of laser hardening techniques to enhance the surface properties of materials, particularly metals. This advanced equipment utilizes a high-intensity laser beam to selectively heat specific areas of a material, followed by rapid cooling through quenching. The machine’s precision allows for controlled and localized treatment, minimizing distortion and thermal damage to the surrounding material. Commonly used in industries such as automotive, aerospace, and manufacturing, laser hardening machines play a crucial role in improving the hardness and wear resistance of components like gears and cutting tools, contributing to increased durability and overall product performance.
