Tetrahedral Amorphous Carbon

Coating Performance

High hardness of this carbon film protects the fine surface finish of the steel tooling against scratching from glass fibers or mineral fillers. Sourcing tools with this coating allows moulders to run longer production cycles without experiencing wear that leads to dimensional drift or parting line flash. Its low coefficient of friction also reduces the ejection force required to remove parts from deep draw cores, which prevents part deformation and reduces the reliance on external release sprays.

Avoiding chemical release sprays prevents surface contamination and simplifies subsequent painting or bonding processes.

Deposition Process

Applying this protective layer involves filtered cathodic vacuum arc deposition at low temperatures to ensure the steel substrate does not lose its hardness. This low temperature deposition process prevents the dimensional distortion of high precision tool steel inserts during the coating run. The resulting film is very thin, typically between one and three micrometres, which preserves the strict tolerances required for microfluidic and optical moulding inserts.

Adhesion depends on careful surface preparation and the use of intermediate bonding layers to manage internal stress.

Wear Monitoring

Molders track the condition of the coating by monitoring ejection force profiles and measuring the surface roughness of the produced parts. When the coating begins to wear away, ejection forces will spike and the surface gloss of the plastic parts can become inconsistent. Early detection of coating wear allows for scheduled tool maintenance before the underlying steel suffers permanent damage.

Stripping and recoating the inserts is a cost effective strategy that avoids the expense of machining new tool inserts from raw blocks.