Laser Cladding: Metal surface enhancing process performed by appling a powdered metal material onto the base surface with a laser. Ensures a bond with minimal dilution, nominal melting and a small heat affected zone.
Laser Technology: A LASER (Light Amplification by Stimulated Emission of Radiation) is an optical source that emits photons in a coherent beam. Laser light is typically near-monochromatic, i.e. consisting of a single wavelength or hue, and emitted in a narrow beam. This is in contrast to common light sources, such as the incandescent light bulb, which emit incoherent photons in almost all directions, usually over a wide spectrum of wavelengths.
Laser Cladding Benefits: The goal of cladding is to deposit a material of desired physical properties over a substrate. Cladding materials are chosen based on whether they need to provide corrosion resistance, wear resistance or higher hardness, depending upon the use of the base part being clad.
Once the physical properties of the application are determined and a cladding material is selected, the process to clad them needs to be decided upon. The cladding method can impact the performance of the cladding material. This is where the benefits in laser cladding over conventional cladding (MIG, TIG, thermal spray) start to show.
Laser cladding provides a strong metallurgical bond with minimal dilution of the base material. This is done with minimal heat input which also results in a small heat affected zone. Laser cladding also has better thickness control and as-clad surface finish than conventional cladding methods.
There is a small zone of base material that does get melted in with the cladding and therefore creates a very good metallurgical bond, versus thermal spray types of cladding that are literally sprayed onto the surface and do not have a solid bond between the two layers.
A major benefit of laser cladding over conventional arc welding is that the thermal input can be precisely controlled, thus yielding minimal dilution and a small heat affected zone. This lower amount of heat input prevents distortion and the base material properties are not detrimentally affected.
The laser process is much more suitable for automation than conventional welding and, while conventional welding is limited to those in wire format, the laser process is compatible with all powdered metal materials, including ceramic.
Dilution: This is defined as the amount of intermixing of the clad and substrate materials. Low dilution means there is very little of the base material mixing in with the clad, leaving a surface layer of cladding that is very close to the pure clad material. This results in material properties that are not compromised and the full affects of the clad can be achieved in one single layer.
Laser Cladding Powders: To develop various powdered metals (cladding powder), the powder must be formed by gas atomization, which allows the powder particle to cool rapidly forming into very small grain size, a common characteristic of powder metal materials. The use of high-speed steel (HSS) powders allows for the formation of more carbide forming elements. Thus, the small grain size and higher carbide formation results contribute to the improved hardness and wear characteristics of powder metal high-speed steel.
Critical Parts or High Wear components: These parts are defined as being a part or assembly that experiences high mortally (failure) or high wear for some reason that is critical to the operation or performance of certain types of equipment. Becasue of their importance, they hold a high value as a part. Failure of these type parts, assemblies, or groups of parts may cause the machinery to go into downtime status, stopping its ability to be productive.
Substrate: A term used in materials science to describe the base material on which processing is conducted to produce new film or layers of material such as deposited coatings.
ISO Certified: Laser Cladding Services, LTD (LCS) has implemented the ISO 9001:2000 Quality Management System (QMS). LCS is ISO 9001:2000 certified and LCS’s Registrar, SAI Global, conducts semiannual surveillance audits of the QMS.
ISO is recognized as the short name for the International Organization for Standardization, a worldwide federation of national standards bodies formed in 1947.
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QMS: A Quality Management System is a set of documented processes within our organization to satisfy the quality-related expectations of customers, company quality objectives and continual improvement.
Tungsten Carbide: LCS was the first to offer laser clad tungsten carbide as an effective alternative to hardfacing by welding, thermal spray or plating. The appeal of a reconditioning process with a low heat affected zone AND an integral bond to various substrates rang true for the oil drilling industry. LCS has been a trusted partner ever since.
Restoration: Bringing a worn part back to its original, or better, condition.
Remanufacturing: Disassembly of worn or defective products and cleaning, repairing or replacing components, then reassembling them back into working condition. The assembly can also be tested and shipped out for its second life.
Product Enhancement: Using LCS’s metallurgy, welding and laser powder coatings technology to make parts last longer or perform better.
Welding Applications:
- GMAW (Gas Metal Arc Welding) or MIG (Metal Inert Gas)
Pros: fast, relatively high levels of deposits, user friendly
Cons: process produces spatter and smoke, more prone to porosity Weld Materials: Mild steel, Nickel, stainless steel, flux cored and hardface wires Typical Application: General metal joining and reconditioning
- GTAW (Gas Tungsten Arc Welding) or TIG (Tungsten Inert Gas)
Pros: superior quality welds, low distortion, free of spatter and smoke, precise control of welding variables (heat)
Cons: requires extremely clean weld surface and is a relatively slow process Weld Materials: Primarily Aluminum and some Stainless steel Typical Applications: spot weld or aluminum welding
- Stick Welding
Pros: equipment is simple, inexpensive and portable; electrode provides its own flux, all position capable
Cons: produces slag which must be chipped off after welding Weld Materials: Wide range of steel electrodes, Nickel, stainless steel, and hardfacing Typical Applications: Nickel on cast iron
- Submerged Arc
Pros: high quality, very high deposition rate (wide bead if needed)
Cons: limited positions; slag to be removed after the weld Weld Materials: carbon steel, flux cored wire Typical Applications: joining plate, cross shafts, wrapper bands
- Hardfacing
Pros: Can be considered instead of laser cladding if the size, geometry or thickness of hardfacing required falls outside the laser cladding parameters
Cons: Lower level of automation, lower tolerance capability and less material selection as compared to laser cladding. Also, due to higher heat input to the part (as compared to laser cladding) there is potential for distortion. Typical Applications: large parts, or geometries not conducive to the laser process
- Wire Arc Spray
Pros: low heat to base part (lower than thermal spray); low distortion of base part
Cons: not a fused bond (better than powder metal thermal spray, bonding strength of 3000 to 8000 psi); must be done in suitable spray booth with adequate ventilation; proper surface preparation is critical Weld Materials: typically use nickel composite Typical Applications: localized “scratched” surfaces, seal surfaces, shaft and bore build up
- Thermal Spray
Pros: low heat input to base part; low distortion to base part; can spray any powdered material as compared to wire arc spray
Cons: bond between weld and base metal (1000 to 6000 psi); proper surface preparation is critical Weld Materials: any powder metal or ceramic; typically use iron base with nickel Typical Applications: localized “scratched” areas, seal surface or bearing bores
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