CVD or PVD

In 1969, Neil Amstrong steps onto the surface of the moon, Charlie Cline sends the first email with the word "login", and Sandvik Coromant presents the first serial samples of replaceable polyhedral plates with wear-resistant CVD coatings.

CVD (Chemical Vapor Deposition) is a process used to obtain high–purity solid coatings by chemical deposition at high temperatures of 800-1000 degrees Celsius. 

To improve the properties of metal-cutting tools use coatings with a crystal structure of chemically inert and refractory compounds: titanium carbide, titanium nitride, aluminum oxide.

The first single-layer primitive coatings made of TiC with a thickness of 4-7 microns applied to non-wettable turning polyhedral carbide plates, contributed to a 50% increase in productivity by increasing speeds from 100-120 to 150-200 m/min. 

Nevertheless, the CVD technology has its drawbacks: high application temperatures negatively affect the substrate; the minimum thickness is 4 microns; chemicals used for the coating process of the tool and by—products are toxic, flammable and corrosive substances. 

The primacy of Soviet and then Russian developments in the creation of the second largest market for coating technology on cutting tools behind the PVD method. In the USSR, in the 80s it was called CIB (condensation with ion bombardment), but due to many specific features of our homeland, PVD technology has successfully and extensively received industrial application from foreign firms. 

PVD (Physical Vapor Deposition) is a vacuum deposition of coatings, in which a thin protective film is obtained by direct condensation of vapor of the applied material 2-6 microns.

The popularity of this method was determined primarily by the fact that PVD most successfully improves the properties of those cutting tools where CVD technology is ineffective and useless. Firstly, PVD is implemented at lower temperatures, no more than 500 degrees Celsius, which allows covering even high-speed steels and carbide plates, without causing damage to the substrate and preserving all the quality indicators of the base. Secondly, PVD can be applied evenly to the sharp edge of the tool, which does not cause it to dull. Thus, this method is successfully used on fine-grained materials and small-diameter end mills. For coating use: TiN, TiAlN, TiCN.

Of the disadvantages of PVD, the following can be noted: a thin layer — a maximum of 5 microns; physical deposition in vacuum is more expensive: a complex technological process + equipment + highly qualified specialists. 

What should I take?

Thin PVD cannot compete with a multi-layer powerful CVD coating, the total value of which can be 20 microns in heavy roughing of steel, cast iron, hardened materials. But for the processing of viscous stainless, heat-resistant steels and non-ferrous materials, a sharp, durable edge is needed, which can only be provided by a PVD coating, and it will also be useful for precise finishing.

Materials used: Sandvik, DormerPramet