CLADDING AWAY The lasers used for laser cladding exhibit a more uniform distribution of energy in the melt pool
High-technology coatings specialist Thermaspray is the only ISO 9001:2015 and ISO 3834-2 certified company offering laser cladding services to industry in Southern Africa.
Laser cladding, or laser metal deposition, is a highly specialised process whereby a metallic surface is melted by a high-intensity laser beam, a tailored metal powder or wire is introduced into the molten pool, and upon solidification, a weld bead is formed as the molten pool is moved over the surface.
Multiple such beads are placed next to each other and overlapped, forming a layer and multiple layers can be deposited on top of one another.
Strictly speaking, laser cladding differs from laser welding in the distribution of energy in the melt pool generated by the laser beam; the lasers used in laser welding typically have a higher concentration of energy towards the centre of the melt pool, allowing for deeper penetration melting, which is required for successful welding applications.
The lasers used for laser cladding, on the other hand, exhibit a more uniform distribution of energy in the melt pool, which results in shallow penetration and subsequently low dilution between the substrate material and the applied overlay material.
Laser cladding technology can deposit a variety of metal and metal alloys onto metallic surfaces, for a variety of purposes; from restoring the dimensions of a worn or damaged surface on an industrial component through to enhancing the corrosion- and/or wear-resistance of a specific surface on a new component. Protecting (or restoring) the surfaces of industrial components by means of a welding-type process is not new, but the advantages offered by doing so through laser cladding are extensive.
As with all thermal spray, cladding and hardfacing processes, a key goal is to achieve a surface composition that fully meets the in-situ wear and/or corrosion property requirements without affecting the metallurgy of the supporting substrate. Laser cladding exhibits low heat input when applied onto a component, especially when compared to methods like metal inert gas, plasma transferred arc or submerged arc welding.
This directly corresponds to cost-savings for the end-user, as there is generally no risk of distorting the component through excessive heat input, local repairs are possible and can be done without adversely affecting the metallurgy of the substrate, and there is often no need for time-consuming post-weld heat treatments after the repair.
Additionally, uniquely shallow heat-affected zones and fine, homogenous microstructures offered by the laser cladding process make it the ideal technology for refurbishment or corrosion- and/or wear protection of the most demanding applications, where traditional repair methods are not feasible.
Laser cladding is typically applied by using a six-axis robot to manipulate the laser head along with a specialised nozzle that delivers the desired metal powder to the molten pool. An inert gas is also used to shroud the molten pool from oxidation. Often, the laser remains stationary over a rotating component, but the laser itself can be moved over a stationary component. The entire process is digitally controlled to allow for precise manipulation of the overlay characteristics, while allowing repeatability whenever multiple jobs need to be carried out.
With technologies ranging from laser cladding to thermal spray, Teflon and polymer coatings, supported by in-house machining and grinding facilities and a metallurgical laboratory, Thermaspray prides itself on providing customers with the highest quality solutions to their needs.
Thermaspray’s laser cladding service is further supported through the expertise of a South Africa-based international welding engineer, Switzerland-based laser cladding specialist and a host of qualified welding procedures for all manner of applications in industries such as power generation, oil and gas, minerals processing, mining and automotive.