Laser hardening is a process with which the wear behavior of components can be affected in a targeted manner.

When laser-hardening – also referred to as marginalized layer hardening – the laser beam with its adjustable focal spot size is guided over the welded surfaces by a robot. The energy of the laser is applied directly to the workpiece surface. This marginalized layer is then heated in a very short period of time and locally limited to the required hardening temperature. The integrated temperature measurement in the beam geometry ensures that the heat input is uniform. The laser beam's interaction time with the surface determines the hardness penetration depth.

How Does Laser Hardening Work?

Using a focused laser beam, the area to be hardened is very quickly heated to the critical temperature and subsequently quenched by the cold component volume. The material distortion is considerably reduced because of how quickly heat is applied with almost simultaneous self-quenching. This is thus considered a low-distortion or even distortion-free heat treatment. The carbon atoms change their position in the metal grid due to the high temperature. This behavior is desirable and called austenitization.

Quick cooling keeps the metal grid from returning to its original shape. The result is martensite (a very tough metal structure that looks very fine under the microscope), which increases the hardness of the material.

Even for large tools from forming technology, laser hardening is a very cost-efficient, extremely fast process for marginalized layer hardening, because it enables partial hardening of selected stressed functional areas on the workpiece surface.

This results in a zonally hard surface with a tough core, and the areas in the immediate vicinity are unaffected. The toughness of the basic material remains unchanged. Track widths from 5 to approx. 30 mm are possible depending on the laser power and system. The achievable hardness penetration depth is about 0.6 mm to 0.8 mm, and with many materials it can be up to 2 mm.

The advantages of laser hardening can be summarized as follows:

  • Zones that are subject to wear can be hardened in a contour-accurate and precise way.
  • Hard marginal zone, tough core
  • Rapid cooling through self-quenching
  • No cooling media required
  • Low-distortion
  • Less or no re-work due to the formation of the hardening path by means of shielding gas.
  • Hardening paths are possible on cutting edges, guide ways, grooves, and
    free-form surfaces with continuous geometric transitions.
  • Hardening is possible in atmospheric conditions without the use of shielding gas.

Removing the workpiece is not necessary when using a mobile laser hardening robot.
Processing can take place on site, which saves an enormous amount of time.

Further advantages of mobile and flexible laser hardening:

  • No transport of components, pressing tools, and molds required.
  • The process is independent of the size of the respective components, pressing tools, and molds.
  • No costs for packaging, transport, and transport insurance of the components.
  • Prevention of possible transport damage.
  • The workpiece may not need to be removed.
  • The customer of the service provider can follow the process directly.
  • Acceptance and quality control right after completion of the process.
    Potential re-work or changes are implemented immediately.
  • Even impromptu additional tasks can be carried out right away.