Nov 29,2025
Die surface treatment technology: coating and modification for“Super Power” of steel
Die surface treatment technology: coating and modification for“Super Power” of steel
Die steel provides a strong“Body”, and surface treatment technology for its wear an indestructible“Armor”. Through physical or chemical methods to form a micron to millimeter level strengthening layer on the surface of the parts, it can solve the core problems such as wear resistance, demoulding and corrosion resistance, and realize the leap improvement of performance.
Principle and performance matrix of mainstream surface treatment technology
Modification technology by diffusion method
Nitriding treatment: the nitrogen atoms into the steel surface, forming a high hardness of the nitride layer.
Gas nitriding: hardness HV 900-1100, deep layer, but slightly higher brittleness.
Ion nitriding: high hardness (HV 1000-1200) , small deformation, environmental protection, is the mainstream.
QPQ: adding oxidation process after salt bath nitriding, both high wear resistance and corrosion resistance.
TD treatment (thermal reaction diffusion) : forming a layer of vanadium, chromium, niobium carbide layer on the surface of the mold.
Performance: high hardness (HV 2800-3500) , wear resistance far more than nitriding and PVD, excellent adhesion.
Coating Technology
PVD (Physical vapor deposition) : deposition of target atoms onto a workpiece surface by arc or magnetron sputtering in a vacuum environment.
Common coatings: Tin (Gold) , TICN (blue-gray) , CrN (silver) , Tialn (purple-black) .
Features: low coating temperature (~ 500 °C) , minimal deformation, smooth surface, both wear resistance and low friction coefficient.
CVD (chemical Chemical vapor deposition) : coating is formed at high temperatures (~ 1000 °C) by a gas phase chemical reaction.
Common coatings: TiC, TICN, α-Al2O3.
Features: strong adhesion between coating and substrate, good coverage (can coat complex lumen) , but high temperature process may lead to substrate annealing deformation.
Scientific selection: matching the best“Armor” for application scenarios
High wear scenarios (glass fiber reinforced plastics) : preferred TD treatment or TIALN PVD coating to provide maximum resistance to abrasive wear.
Anti-adhesion, easy demoulding (elastomer TPU, PP) : CrN PVD coating or PTFE composite coating has extremely low surface energy and excellent anti-adhesion effect.
Corrosion resistance (PVC, flame retardant) : PVC mold preferred stainless steel substrate + polishing, or on ordinary steel for hard chromium plating. The CRN coating also has good corrosion resistance.
Both wear and lubrication (high-speed injection) : TICN coating with high hardness and low coefficient of friction, can effectively reduce the movement of thimble, slider wear and occlusion.
The key to successful application: the synergy between substrate and coating
“Hard underlay soft armor” is ineffective: the coating itself is thin and requires a hard substrate for support. Generally, the hardness of the substrate should be at least HRC 48-52, otherwise the coating will peel off early due to the plastic deformation of the substrate.
Perfect surface preparation: mirror finish must be applied before coating, as any surface imperfections will be magnified after coating. Uniform and consistent Surface roughness is the guarantee of coating uniformity and adhesion.
Adaptation of structural design: sharp corners and cutting edges are avoided, and it is recommended to treat edges and corners as rounded corners above R0.2 to prevent cracking or spalling of the coating at these stress concentrations.
Conclusion:
Surface treatment is a systems engineering. Only in-depth understanding of the principles and boundaries of various technologies, accurate selection according to specific failure modes (wear, corrosion, Adhesion) , and strict control of the quality of the substrate treatment, can this layer of micron-level“Super Power” into the tool life and production efficiency of the huge improvement.
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