Meaning
Surface treatment technology using amorphous carbon films provides extreme hardness and low friction coefficients for metal tooling components. Applying a dlc coating to injection mould cores, cavity inserts, and ejector pins reduces abrasive wear during the processing of highly filled polymer compounds. The surface modification operates as a thin barrier layer that prevents direct metal-to-metal contact without altering the dimensional tolerances of precision tool components.
It stops applying where mechanical impact loads exceed the substrate yield strength or where operating temperatures degrade the hydrogenated carbon structure.
Layer Deposition
Vacuum plasma processes deposit thin amorphous carbon layers onto pre-ground tool steels at temperature thresholds that preserve the underlying heat treatment. Physical vapor deposition methods allow the dlc coating to bond tightly with substrate alloys when intermediate adhesion layers like titanium or chromium are present. Thin layer growth occurs at sub-micron rates, yielding finished thicknesses between one and three micrometers.
Substrate micro-cracking occurs if compressive internal stresses within the carbon matrix are allowed to build up excessively during process execution.
Frictional Resistance
Low coefficient of friction values inherent to amorphous carbon reduce drag forces during part ejection. Running cores with dlc coating eliminates the need for liquid lubricants that contaminate moulded medical parts. Shear stresses along sliding interfaces drop sharply, which lowers maintenance requirements.
Unlubricated steel pins wear down under high cycle rates.
Wear Mitigation
Hardness levels exceeding twenty gigapascals protect tool steels against scratch damage caused by glass fibers and abrasive mineral fillers. Continuous processing of reinforced engineering resins causes severe substrate erosion on uncoated cavity surfaces, leading to flash formation and dimensional drift. Integrating a dlc coating across high-velocity flow paths minimizes gate erosion and maintains consistent shear heating conditions across millions of moulding cycles.
Tooling life expands significantly when abrasive resins pass over hardened surfaces rather than raw tool steel. Abrasive filler particles cut through soft steel boundaries, but the diamond-like structure absorbs contact force without surface loss.
