Meaning
Physical degradation of diamond like carbon layers occurs through mechanical abrasion and thermal fatigue during the molding cycle. Most instances of dlc coating wear result from the processing of glass filled resins that scour the surface of the cavity. Film layers provide a low friction coefficient but are susceptible to micro cracking when the substrate steel undergoes thermal expansion.
Friction Reduction
Surface lubricity helps in the ejection of deep draw parts with minimal draft angles. High dlc coating wear increases the force required to push the part off the core.
Maintenance Interval
Tooling life depends on the periodic inspection of the protective layers. Measuring dlc coating wear allows a facility to schedule recoating before the underlying tool steel is damaged. Polishing a worn tool takes more time than stripping and reapplying a vapor deposition layer.
Surface Quality
Aesthetic requirements for medical and optical parts necessitate a perfect finish. Even minor dlc coating wear produces visible marks or changes in the gloss level of the plastic surface. Replacing the coating at the first sign of thinning prevents the production of scrap parts that fail visual inspection.
Consistent monitoring of the gate area is necessary because the high velocity of the melt causes the fastest depletion of the protective film.
