Hardening | Direct diode lasers (DDL)


Laser hardening is a method of heating the material surface. In laser hardening using DDL, it is possible to quench a very small and narrow areas by selecting the focused beam size. This makes it possible to reduce distortion and achieve high-quality hardening.

Advantages of laser hardening using DDL

High-quality hardening

  • Minimal distortion due to local heating
  • Allows hardening in small batches and multiple types
  • Top-hat beam intensity distribution ensures uniform hardening

Focused beam pattern and profiles (example)

・DDL (top-hat beam shape)

・Fiber output laser (gaussian beam shape)

Thermal image during hardening


・Fiber output laser

Process reduction

  • Needs no correction process since distortion is minimal
  • Localized heating capable of self-cooling eliminates the need for a cooling process
  • Quench from one piece means there is no waiting time for the process

Running cost reduction

  • Improves overall cost performance by reducing various process
  • No need to store, control and adjust the cooling water and oil
  • No need to fabricate coils for induction hardening

Realization of space saving

  • Self-cooling eliminates the need for a cooling device and process after quenching

Comparing laser hardening with induction hardening

The table below compares laser hardening with induction hardening. Induction hardening is method of hardening by heating the surface of material by causing electromagnetic induction with high-frequency electromagnetic waves.


  Laser hardening Induction hardening
Distortion Small Large
Post-process Not required Required
Cooling Not required Required
Coil (jig) Not required Dedicated coil is required for each product
Hardening depth Shallow Deep
Heating area Local Overall

Heating area

・Laser hardening 

・Induction hardening

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