CoHard uses a laser beam to harden components which, due to their geometry, were not previously suitable for laser hardening – for example, drill hole diameters of less than 10 mm. The area in which the laser energy is absorbed is extremely narrow, which minimizes or eliminates warping of the workpiece. The hardening of the diameter takes place simultaneously because the profile of the laser beam is rotationally symmetric.

The product is currently in a very promising prototype phase. Series-production optics will be developed by working together with customers and their individual requirements.

Function description

At the heart of the new coaxial laser hardening process is an optic that focuses the laser beam annularly using cone-shaped lenses known as axicons. The diverging laser beam strikes the inner wall of the hole behind the focal plane at a low angle of 5° to 15°. Axial shifting of the optic makes it possible to harden the entire surface.

Areas of application

  • Laser hardening
  • Guides and sealing surfaces
  • Grooves
  • Tight drill holes
  • Blind hole end faces


  • Narrow range of heat input for less distortion
  • No optical elements inside the bore, zero risk of contamination or collision
  • Rotationally symmetrical beam profile, no need to rotate component
  • Flexible for a wide range of bore diameters and lengths


  • Absorption of laser energy at a steep angle in the 40% range
  • Static component fixing, feed movement generated by the axial movement of the optics
  • Integrated temperature control

Supported Laser

  • Fiber lasers
  • Solid state lasers
  • Diode lasers


  • Monitoring camera for setting up the process
  • Static part clambing, feed motion by axial movement of optics


  • Integration of a camera + crosshair generator for adjustment
  • Integration of a pyrometer to use a closed loop control
Wave length1030 – 1080 nm
Laser powerMax. 8 kW
Beam parameter product (BPP)<30mm*mrad
Akzeptanz-Halbwinkel125 mrad
Processing head: IP64Processing head: IP64
Fiber couplingsTrumpf-B, Trumpf-D, Optoskand QBH
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