Production of a knife

Die Herstellung eines Messers

From blank to knife

Hardening

The hardening process is an important step since it is crucial for the final quality of the steel. The correct hardening temperature and the duration of the treatment must be precisely maintained. The cutting abilities and corrosion resistance of the blade depend entirely on the right heat treatment.

Special steel “FRIODUR®”, ice-hardened

ZWILLING J.A. HENCKELS has optimised the hardening process. FRIODUR®, a protected brand name of ZWILLING J.A. HENCKELS, identifies products whose steel has been especially ice-hardened. This process involves four stages:

  • Heating up the steel to more than 1000°C
    This improves the molecular structure for the benefit of higher hardness.
    Higher hardness = longer lasting sharpness.
  • Cooling down to room temperature
    The cooling takes the pressure off the material and ensures an especially flexible stability. This adds safety when used and prevents blades from breaking.
  • Freezing to -70°C
    Ice-hardening strengthens the corrosion resistance and protects better against rust.
  • Reheating twice to just below 250°C.
    The result: exceptional hardness, high elasticity and very high corrosion resistance.

Further processing

The final shape is achieved by grinding. Surface treatment (finish) is accomplished by:

  • grinding
  • fine-grinding
  • dry-fine
  • grinding
  • polishing

Assembly

This involves joining the prefabricated blade and handle to complete the actual knife.

Adjusting

Following assembly the joint between handle and bolster is adjusted and levelled. At this step excess material is removed to make sure that the joint is absolutely smooth to keep out bacteria and germs.

Honing

Honing gives the knife its sharpness. Honing is being done with fine grindstones on special machines or on a felt disc. Thus the honed area achieves a degree of evenness from the tip to the bolster which, in combination with the hardness of the steel, ensures an unprecedented degree of cutting edge retention. Monitored by laser each knife is getting its optimum cutting angle. This is why ZWILLING J.A. HENCKELS knives are sharper than ever and retain their cutting properties much longer.