Laser Cladding

Pore-free and crack-free layers with a long lifetime, high surface quality and exceptional durability.

Cladding Process

Laser cladding is realized either as wire (laser hot wire cladding) or powder cladding. The laser beam creates a molten pool at the workpiece surface, to which is simultaneously added the laser coating material (wire or powder) molten by the laser. The exposure time is short, which creates only a short delay as the cooling is quick. The result is a layer that is connected with the basic material metallurgically. It is tougher than those coatings created by thermal spraying, and compared to hard chromium plating, for example, it is harmless to health, too.

Cladding technology advantages of diode lasers

The top-hat beam profile of a diode laser, part of the laser cladding equipment, creates a particularly even molten pool, which provides fine-grained, pore-free and crack-free coatings of the workpieces. Post-processing is thus reduced to a minimum. When integrated into systems for the Extreme High-Speed Laser Cladding, as developed by Fraunhofer ILT, our diode lasers are also suitable for creating very thin cladding coatings which until now could only be realized with hard chromium plating.

Advantages at a glance

low exposure time and depth of the laser
metallurgical connection of layer and basic material
layers are more resistant than thermal spray coatings
high surface quality and low warpage, with almost no post-processing necessary
short laser cladding process period, high-energy efficiency

Journal

Less brake dust by laser-coated brake discs

Friction between the brake disc and brake lining produces fine dust, which accounts for a relevant proportion of the total fine dust load. New coating technologies make it possible to manufacture low-wear brake discs with significantly reduced fine dust emissions. An additional layer on the base material - tungsten carbide, for example - achieves high abrasion resistance and enables the particularly economical production of a new generation of brake discs.

Application examples

process laser cladding — Source: Technogenia

Drilling tools

The development of oil and gas fields requires high-performing drilling tools. These are subjected to huge stress and would not reach long lifetimes without wear protection. That is why special coatings, that are more and more frequently realized with the laser coating technology, have become the standard for some time now. Here, Laserline’s LDM and LDF diode lasers have achieved outstanding results: excellent adhesion, high precision, almost no porosity, limited crack formation, a high degree of hardness, and low deformation. In most cases, the created surface does not require any further mechanical processing. In comparison, conventional hard plating methods such as plasma powder cladding do not attain sufficiently long lifetimes.

For customers engaged in oil extraction, mining, metal and paper industries, Technolgenia coats with the help of Laserline's diode laser components with a special tungsten carbide powder.

Case study to download [PDF]

Agricultural machinery

The typical carbide layers that protect saw-blades, disc harrows or counter blades from wear and corrosion can be optimally realized with the help of diode lasers. Distortion and mixing are kept particularly low by a quiet molten pool and minimal heat input. Coating thicknesses as well as track widths can be variably and specifically built up. Oversizes during coating are kept to a minimum, so that the economic efficiency combined with the technical advantages make a strong team for agricultural components.

Coating of hydraulic cylinders for the mining industry

A growing market is laser coating of hydraulic cylinders in technical mining facilities for example coal extraction. The coating of the cylinder corrodes very quickly under the local atmosphere which leads to leaking hence a replacement or new coating will be necessary. Until now chrome plating was the primary method which will be replaced more and more by laser coatings due to their superior durability. The specific increase of durability can’t be quantified yet however current results show an increase in the lifetime of more than 100%.

Coating of heat exchangers

The main motivation is the protection against highly corrosive gases or liquids which come into contact with the metal heat exchanger affect negatively its life cycle. Therefore nickel alloys with low hardness properties are mostly used which avoids cracking and can be applied up to 1 mm thickness. Even at high temperatures they lead to a better wear protection against corrosive media. Deposition rates of 8 kg/h are possible.

Chlorine attacks metal, a fact that is known all too well by operators of biomass facilities and incineration plants. But why? The boiler walls of such plants consist of water-bearing steel pipe systems that absorb the thermal energy of the firing and then transfer it to the water-steam circuits. But the chlorine in the flue gas of the firing breaks down the pipes. Untreated, they are often no longer usable after one year. It seems reasonable then to assume that this cannot be economical.

Meanwhile, many plant operators therefore count on anti-corrosion coatings. This is already worth the effort as soon as the duration of the operation is doubled — and even more can be achieved: compared to uncoated pipes, and depending on the applied material and physico-chemical load, a tripling or quadrupling of the lifespan is possible.

...more >

sample high speed laser cladding — Source: Fraunhofer ILT

High-Speed Cladding in place of hard chromium plating

As the most successful coating method to date, hard chromium plating is being threatened by an EU-wide prohibition, such that the industry is searching for alternatives. Hitherto, laser-based cladding seemed unsuitable because the process was too slow and did not allow for sufficiently thin coatings. However, the Fraunhofer Institute for Laser Technology (ILT) has developed a patented method, which enables high processing speeds at low-layer thicknesses and needs less power than regular cladding, namely, extreme high-speed laser cladding. Laserline's diode lasers have been successfully used in High-Speed Cladding. Initially, the method was only designed for coating rotationally symmetric components, but is now supposed to be suitable for laser coating of other components in the foreseeable future.