Thin Film Coating FAQ's

Q: What is PVD Coating?
A: PVD coating is an abbreviation for Physical Vapor Deposition.  A technology developed to deposit thin film coating compounds on a variety of materials. The process temperature of this technology generally is in the range of 250º - 600º Centigrade, which allows the process to be applied to a broad range of materials.

Q: What is CVD Coating?
A: CVD is an abbreviation for Chemical Vapor Deposition. A technology developed to deposit thin film coating compounds on a limited range of materials. Due to the elevated process temperature of CVD coating technology, commonly applied at 1000º Centigrade, this process is not applicable to certain grades of tool steel.

Q: What benefits can be expected of thin film coating?
A: Reduced operating cost achieved through increased up time on equipment. Increased productivity achieved through additional parts being produced per tool purchased. Additional cost savings may be achieved by the elimination of expensive coolants and their disposal whenever dry machining becomes a possibility.

Q: How should tools be prepared for coating?
A: The most important aspect of preparation is cleanliness. To achieve the proper adhesion of the coating compounds the surface of the tools must be free of contaminants such as oils or wax which are often found in protective dip seal materials. The presence of any oxidation from thermal processing or rust must also be removed from the surfaces prior to coating.

Q: How thick are coating compounds?
A: Coating thickness measurements are stated as Micron units. One Micron (µ) is equal to .00003937. General coating compound thickness ranges are from 2-12 Microns depending on the process used and the compound being deposited.

Q: Does coating affect surface finish?
A: Coating can add surface roughness due to the deposition process.  This can be overcome by doing post-coat polishing to the critical working surfaces. In general coating compounds will not improve surface finishes. The coating deposition will conform to the surface condition of the part. Coating compounds will not fill voids or bridge gaps in surface finishes.

Q: What geometry can be coated?
A: The nature of CVD coating compounds being formed by reactive gases flowing at high temperature provides a uniform homogeneous coating being deposited on all surfaces including internal diameters. PVD coatings are "line of sight" and are deposited on the surfaces of the components that are presented to the coating target plasma. PVD coating process technology uses mechanical part rotation ranging from single axis to triple axis rotation in order to achieve coating on multiple surfaces. The general rule of thumb for PVD coating of I.D. surfaces is a coating depth of 1X the internal diameter will be achieved. This factor becomes less as the I.D. becomes smaller than .500.

Q: Is masking of surfaces possible?
A: Masking surfaces not requiring coating is relatively easy when coating is being done with PVD technology. Masking when coating with CVD processing is very difficult and in most cases not practical.

Q: Is there an optimum substrate to coat?
A: No. The substrate and geometry are dependent upon the application. The best results are achieved when the proper substrate and coating process and compound are engineered prior to the build of the tooling. A poorly designed tool or a tool made of an inappropriate substrate will not benefit from coating. Please refer to our "material coatability" list for additional information.

Q: Can coating be removed?
A: In most cases yes. Some complex coating compounds are more difficult to remove than others and require special chemicals to achieve removal. In general it is common practice to coat over existing coatings when part tolerance allows. Damage to substrates such as carbide and high cobalt content steel such as M-42 is a risk when considering stripping old coating.

Q: Will coating change my part size?
A: The coating compound will only add a few microns of thickness to the part. Concern over substrate movement needs to be discussed when considering CVD coating of steel substrates.  Please consult our technical department when considering CVD coating of steel material.

Q: Should the hardness and lubricity of the coating compound be a concern?
A: While both of these characteristics are very important to the performance of the coating they should not be the determining factor in the choice. It is more important to choose the proper substrate and match the proper coating process and coating compound for your application.  The physical numbers that are associated to the specific coating compound are statements of tests conducted on controlled substrates and controlled surface finishes.  They are very difficult to correlate to the performance of a coating compound on a specific application.