Coating Selection Guide
Find the material you cut, read across to the coating that earns its place, the one-line reason, and what to avoid. Specs and next steps follow.
1. Pick by work material
One page, application first. Each row is the coating the RobbJack chart rates best for that material, why, and the films that don't belong on it.
| Work material | Recommended coating | Why | Avoid |
|---|---|---|---|
| Aluminum | Uncoated (the most popular choice). Step up to DLC; use Diamond (DCC) on high-silicon aluminum.Most aluminum runs well on a bare edge. DLC pays when built-up edge or tool life is the problem. Diamond is for the abrasive high-silicon grades.Avoid: AlTiN, TiCN, TiN | Most aluminum runs well on a bare edge. DLC pays when built-up edge or tool life is the problem. Diamond is for the abrasive high-silicon grades. | AlTiN, TiCN, TiN |
| Copper, brass & magnesium | DLCVery low friction (0.05–0.15 COF) keeps chips flowing clean and stops built-up edge on non-ferrous metals.Avoid: AlTiN, TiCN, TiN, Diamond | Very low friction (0.05–0.15 COF) keeps chips flowing clean and stops built-up edge on non-ferrous metals. | AlTiN, TiCN, TiN, Diamond |
| Plastics | DLCA slick, low-friction edge gives clean chip flow and a high-finish cut.Avoid: AlTiN, TiCN, TiN, Diamond | A slick, low-friction edge gives clean chip flow and a high-finish cut. | AlTiN, TiCN, TiN, Diamond |
| Graphite & composites | Diamond (DCC). DLC is a good second choice.These materials are abrasive and wear carbide away. CVD diamond is the coating made for abrasive composites and graphite.Avoid: AlTiN, TiCN, TiN | These materials are abrasive and wear carbide away. CVD diamond is the coating made for abrasive composites and graphite. | AlTiN, TiCN, TiN |
| Steel (soft / unalloyed) | AlTiN. TiCN or TiN also work.AlTiN is built for heat: high-speed and dry machining where the edge runs hot. TiN is the proven all-rounder on soft steels.Avoid: DLC, Diamond (never put diamond in iron) | AlTiN is built for heat: high-speed and dry machining where the edge runs hot. TiN is the proven all-rounder on soft steels. | DLC, Diamond (never put diamond in iron) |
| Cast iron | AlTiN or TiCN. TiN also works.TiCN adds abrasion resistance and toughness for interrupted cuts. AlTiN handles the heat.Avoid: DLC, Diamond | TiCN adds abrasion resistance and toughness for interrupted cuts. AlTiN handles the heat. | DLC, Diamond |
| Stainless steel | AlTiN. TiCN or TiN also work.High-temperature AlTiN (rated to 900 °C) holds up where the edge runs hot.Avoid: DLC, Diamond | High-temperature AlTiN (rated to 900 °C) holds up where the edge runs hot. | DLC, Diamond |
| Pre-hardened & tool steel (30–45 HRC) | AlTiNHard milling runs hot; AlTiN keeps its hardness (3,300 HV) to 900 °C. TiCN works on steels below its 400 °C limit.Avoid: TiN, DLC, Diamond | Hard milling runs hot; AlTiN keeps its hardness (3,300 HV) to 900 °C. TiCN works on steels below its 400 °C limit. | TiN, DLC, Diamond |
| Hardened steel (over 45 HRC) | AlTiN onlyThis is the hardest film in the lineup (3,300 HV) and the highest temperature rating (900 °C). Hard milling needs both.Avoid: TiCN, TiN, DLC, Diamond | This is the hardest film in the lineup (3,300 HV) and the highest temperature rating (900 °C). Hard milling needs both. | TiCN, TiN, DLC, Diamond |
| Titanium | AlTiNTitanium runs hot. AlTiN is the high-temperature film (rated to 900 °C).Avoid: DLC, TiN, Diamond — and TiCN: it is limited to 400 °C and these alloys run hot | Titanium runs hot. AlTiN is the high-temperature film (rated to 900 °C). | DLC, TiN, Diamond — and TiCN: it is limited to 400 °C and these alloys run hot |
| Inconel & superalloys | AlTiNNickel superalloys run hot. AlTiN keeps its hardness where the other films lose it.Avoid: DLC, TiN, Diamond — and TiCN: it is limited to 400 °C and these alloys run hot | Nickel superalloys run hot. AlTiN keeps its hardness where the other films lose it. | DLC, TiN, Diamond — and TiCN: it is limited to 400 °C and these alloys run hot |
2. Coating specs
The four PVD and DLC films RobbJack applies, with the RobbJack name you'll see on the tool page and the part-number suffix that orders it. Diamond (DCC) is listed with who applies it.
| Coating | RobbJack name | Color | Hardness | Max service temp | Friction (COF) | Thickness | Suffix | Applied by |
|---|---|---|---|---|---|---|---|---|
| AlTiN | Scorpion Stinger | Violet-Black | 3,300 HV | 900 °C | 0.5–0.6 | 1–4 μm | -A | Crystallume PVD |
| TiCN | Python Scales | Gunmetal Grey | 3,200 HV | 400 °C | ~0.4 | 1–4 μm | -C | Crystallume PVD |
| TiN | King Cobra | Gold | 2,800 HV | 600 °C | 0.4–0.5 | 1–4 μm | -T | Crystallume PVD |
| DLC | Black Mamba | Black | 2,000 HV | 450 °C | 0.05–0.15 | 1–4 μm | -DLC | Crystallume PVD |
| Diamond (DCC) | Diamond Coating (CVD) | Spec sheet on request | Spec sheet on request | Spec sheet on request | Spec sheet on request | Spec sheet on request | -D | Crystallume |
A thickness of 1–4 μm works out to about 0.00004″ to 0.00016″ per surface — thin enough that a coated part still gauges. Uncoated tools carry no suffix. Some tools ship already coated, and their base part number carries no added suffix.
3. Coating services for your own parts
Your parts, the same production films
Crystallume PVD applies the same production PVD and DLC films to customer parts, including slides, bolt carriers, knife blades, mold components and production hardware. Start with a few sample parts in their production heat-treat and finish, then move to production once they prove out. See crystallumepvd.com.
RobbJack slitting saws can be ordered coated. Coating is priced by saw diameter for saws up to .750″ thick; ask about larger sizes.
Prove it on your part
Request a test tool, which comes with a performance guarantee: run a RobbJack against the tool you use today, and if it doesn't beat it, we'll make it right. Tell us the material and the operation, and an application engineer will match the tool and the coating. Start from the Speeds & Feeds calculator as your baseline.
Production tools are ordered through your cutting-tool distributor. Find a distributor. Questions: (800) 527-8883.
Who applies what
The numbers behind the picks
- 900 °C
- AlTiN service temperature
- 0.05–0.15
- DLC coefficient of friction
- 1–4 μm
- film thickness — a coated part still gauges
Keep going
Not sure which coating?
Tell us the material, the operation and the tool you run today. An application engineer will match the tool and the coating, and the test tool is guaranteed to beat what you're using.