Wrap-up
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PVD coatings
The thin-film hard layer. TiN, CrN, AlTiN, TiCN — what they are, what they're good for, and what those colors actually mean.
Tying it together
The basics
PVD stands for Physical Vapor Deposition. The process happens inside a vacuum chamber at relatively low temperatures (typically 200-500°C). A solid metal target — titanium, chromium, aluminum, or a mix — is bombarded by ions and atomized into a vapor. The vapor reacts with a process gas (typically nitrogen) and deposits as a thin, hard ceramic film on the tool surface. The bond is mechanical — the coating interlocks with the tool's surface texture, which is why surface prep matters as much as it does (next lesson).
Per The Fabricator and Richter Precision's coating glossaries, the common stamping/forming coatings break down like this:
| Coating | Hardness (Hv) | Color | Best for |
|---|---|---|---|
| TiN (titanium nitride) | 2200-2400 | Gold | General-purpose wear resistance, cutting tools, low-end forming |
| CrN (chromium nitride) | 2500-2700 | Silver-gray | Corrosion resistance, lower friction, wet environments, food contact |
| TiCN (titanium carbonitride) | 3600-4000 | Blue-gray | Higher hardness than TiN, better wear, moderate temperature limit |
| AlTiN (aluminum titanium nitride) | 3500-4500 | Violet/purple-gray | High-temperature service (forms protective Al₂O₃ at temperature), hot work, high-speed cutting |
| TiAlN (titanium aluminum nitride) | 3300-3500 | Violet | Similar high-temp story; subtly different layer chemistry than AlTiN |
Thickness
Per The Fabricator's stamping-tool guidance, the minimum PVD coating thickness for stamping and forming applications is 4-5 µm. Thinner won't survive the contact loads. Cutting tools sometimes run 2-3 µm, but stamping needs the thicker end. Coatings above ~8 µm start to develop their own internal stress problems, so most production coatings live in the 4-7 µm range.
Selection logic in plain English
- Cheap general-purpose, low temp: TiN.
- Corrosion concern, water-based lube, lower friction: CrN.
- Higher wear resistance at moderate temperature: TiCN.
- High operating temperature (>500°C), hot work, high-speed cutting: AlTiN.
These are starting points, not final answers. Real selection requires knowing the substrate, the application, the failure mode, and the operating environment. We'll come back to that in lesson 8.
A real-world frame for the price-vs-life conversation
From The Fabricator's published field data on stamping operations: an uncoated punch ran 10,000 parts. The same punch geometry with a CrN/CrC multilayer coating ran 55,000 parts. The same geometry with AlTiN ran over 100,000 parts. The coating cost on the production run was a small fraction of the avoided cost of punch replacement and downtime.
What this means on the shop floor
- The coating color tells you what you're working with, but only roughly — TiN is always gold, but two suppliers' AlTiN can look subtly different. Don't rely on color alone to verify coating type; ask for documentation.
- Coatings work in compression, not tension. They love loads that push them into the substrate, hate loads that try to peel them off. Sharp internal corners on a coated tool are concentration points; soften any radii you can in the design.
- Coatings don't survive bad substrates. We'll spend lesson 7 on surface prep and lesson 9 on the egg-shell failure mode, both of which are about the same underlying truth: the coating is only as good as what's underneath it.
Next: the most underestimated step in the whole pipeline — surface preparation.