Laser Hardening

In the case of laser skin hardening, the material (carbonaceous material) is heated up for a short time above austenitizing temperature and is transubstantiated by fast cooling down into the martensitic structure. Heat is generated by absorbing the laser radiation on the surface and the material is quenched by heat transportation inside. The surface may not melt up. The hardening depth is limited to approx. 1 to max. 1.5 mm by heat conductivity and self-quenching. Mainly the spot geometry of the laser at the processing spot and the feed rate determine the chronological temperature pattern. For hardening of paths preferredly a line-formed spot geometry is used (long axis cross to feed direction). For complex geometries or low-value production, it can also be generated very flexibly by using a scanner which moves a focussed laser beam very fast and thus builds up a quasi-stationary line-formed intensity distribution.

Applications

• Cam disc
• Precision guide rails
• Punching tools
• Cutting Tools
• Cog wheels
• Synchronous rings
• Extruder screw
• Torsion spring (see above)
• Shafts

Due to better laser beam absorption on steel surfaces with shorter wavelengths, solid-state laser are usually more efficient and are more cost-effective for hardening processes than CO2 lasers. High-power diode lasers, providing an optimal wavelength (800 – 1000 µm), a rectangular beam and high efficiency with a small set-up, are particularly suitable.