It has become a common practice to apply a thin wear resistant coating to Tools, Dies and Molds to extend the life and preserve critical working areas while manufacturing various parts ranging from automotive stampings to die cast components.
Physical Vapor Deposition (PVD) is considered a low temperature coating application process as work is processed at temperatures lower than those used in the tempering process done after normal heat treat (850̊-900̊ F).
High temperature processes such as CVD or TD (1750̊ F or greater) were used prior to the improvement of PVD technology but due to tool distortion and dimensional changes from these coatings the PVD Duplex process has become the process of choice for most applications.
In summary... Why PVD?
PVD coating provides unlimited re-coating without damage to the substrate chemistry and when proper heat treat and tempering practices are followed critical tooling tolerances are maintained each time the tool is re-processed.