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Ikmanda Roswati
Ikmanda RoswatiPh.D.Indonesia
Ultrafast photonics and laser-matter interaction
Published
Jul 22, 2026

Hard Coatings & PVD/DLC Wear Film Laser Cleaning

Thin hard wear films on tool steel and carbide come off under pulsed light so an edge can take a new coat. What matters is not nicking the cutting edge, capturing cobalt-bearing dust from carbide, and proving the strip on a spare tool because these skins are thin and the host sits close underneath.

Common questions on laser removal of hard coatings

  • What makes hard coatings like DLC and PVD difficult to strip?

    Hard coatings such as diamond-like carbon and PVD nitrides are built to resist abrasion, heat, and chemical attack, which is exactly why manufacturers apply them to cutting tools and forming dies in the first place. That same resistance works against removal because hardness limits mechanical abrasion, and chemical inertness stops solvents or acids from softening the layer without long soak times that also attack the substrate underneath. Laser stripping instead exploits the difference in how.

  • How does laser removal compare to grit blasting on hard coatings?

    Laser removal skips abrasive media entirely, so it avoids embedding grit particles into the substrate or rounding sharp tool edges. Grit blasting removes the coating and a layer of substrate together at the same rate, while a tuned laser can stop right at the coating to substrate interface.

  • Why do femtosecond lasers outperform picosecond lasers on DLC?

    Femtosecond pulses deposit energy into the coating faster than the material can conduct it away, so the diamond-like carbon layer ablates with a narrower heat affected zone than picosecond pulses produce. Comparative work on DLC cleaning found that shorter pulses limit graphitization at the coating edge, a change that Raman spectroscopy detects as a shift toward disordered carbon. Picosecond systems still clear the coating, but they leave a wider transition zone, which matters more on.

  • What laser safety rules apply when stripping hard coatings?

    Laser stripping of hard coatings runs at power and pulse settings that can injure eyes and skin well beyond the coating removal zone, so the same safety framework that governs any industrial laser applies here too. ANSI Z136 sets the laser safety classification, nominal hazard zone calculations, and eyewear requirements that operators follow regardless of whether the beam targets a diamond-like carbon tool coating or a painted panel. Cal/OSHA and OSHA reinforce those requirements through.

  • Does laser stripping work on coated high speed steel tools?

    Tool steel responds well to laser stripping of CrN and similar nitride coatings, and research on high speed steel tooling shows the coating separates from the substrate before the underlying steel reaches damaging temperatures. Reground and recoated tools can return to service without machining away extra base material.

Sources(7 references)
  1. Segmental Laser Stripping of Thin Coatings on Monolithic Cutting Tools mmscience.eu (opens in new tab) — Segmental laser stripping removes hard coatings in controlled passes instead of one aggressive step
  2. Decoating of TiN-Coated Cemented Tungsten Carbide Tools by Laser Ablation for Remanufacturing Purposes, Circular Economy and Sustainability, Springer, 2026 doi:10.1007/s43615-026-00880-9 (opens in new tab) — Laser decoating targets the interface between a hard coating and the substrate
  3. Laser de-coating of hard DLC coatings from tungsten carbide cutting tool journals.sagepub.com (opens in new tab) — Laser decoating removes DLC coatings from tungsten carbide without embedding abrasive media in the substrate
  4. Comparing picosecond to femtosecond laser pulse duration in laser cleaning processes with a focus on diamond-like carbon (DLC) coating removal link.springer.com (opens in new tab) — Femtosecond pulses leave a narrower heat affected zone than picosecond pulses on DLC coatings
  5. Raman Studies of Structural Changes in Diamond-like Carbon Films on Si Induced by Ultrafast Laser Ablation jlps.gr.jp (opens in new tab) — Raman spectroscopy detects graphitization at the coating edge after picosecond laser cleaning
  6. Stripping of CrN from CrN-coated high-speed steels sciencedirect.com (opens in new tab) — Laser stripping removes CrN coatings from high speed steel tooling before the substrate overheats
  7. 8 CCR §5206 — Cal/OSHA Hexavalent Chromium Standard (General Industry) dir.ca.gov (opens in new tab) — Hexavalent chromium standard governs re-coat planning when chromium chemistry was in the stripped film

Steps to strip a hard coating without rounding the edge

Work begins by naming the coating chemistry and thickness so the first pass has a published energy to aim at. Energy rises only after a test piece shows clean carbide without edge rounding.

1Identify film and host before you set energy
  • Do not copy a rust or paint preset onto a coated insert; read the traveler for CrN, TiN, TiAlN, AlTiN, or DLC and note whether the body is high-speed steel or cobalt-bonded carbide.
  • Treat each chemistry as its own coupon job.
2Coupon the strip under live extraction
  • On a labeled scrap insert, walk pulsed energy until bare substrate shows.
  • Keep HEPA extraction on for nitride and carbon dust, especially on WC-Co edges where cobalt fines matter.
3Inspect, then hand off to re-coat
  • Reject any land that still shows coating color under magnification.
  • Send cleared tools into the re-sharpen and re-coat plan only after the lot passes edge and adhesion checks.
Sources(1 reference)
  1. Laser stripping of TiAlN coating to facilitate reuse of cutting tools, Proc. IMechE Part B, 2011 doi:10.1177/0954405411414313 (opens in new tab) — TiAlN strip work on WC-Co cutting tools gives the first-pass energy shops aim at before coupon confirmation

PVD and CVD wear stacks, not paint, anodize, or rust

This scope covers thin PVD and CVD wear coatings on cutting tools and dies, including CrN, TiN, TiAlN, AlTiN, and DLC stacks measured in micrometers. It does not cover thick organic paint, anodize, galvanize, or field rust, and laser work here means selective decoating of that wear skin on carbide or steel tools so the edge can be re-sharpened or re-coated.

Sources(1 reference)
  1. Decoating of TiN-Coated Cemented Tungsten Carbide Tools by Laser Ablation for Remanufacturing Purposes, Circular Economy and Sustainability, Springer, 2026 doi:10.1007/s43615-026-00880-9 (opens in new tab) — Remanufacturing work on TiN decoating of cemented tungsten carbide tools frames the selective-strip scope

Cobalt and chromium chemistry set the stop points

Cobalt binder in cemented carbide and chromium in CrN stacks sets exposure stops before energy rises on a production insert. Those same stops carry over to cell setup, where eye and face protection rules apply in Class 4 laser strip cells and extraction must stay live whenever nitride or carbon dust leaves the scan path.

Cemented carbide tools with cobalt binder under pulsed strip — Cobalt metal and dust carry airborne limits that sit below many shop iron-oxide habits, and overdriving a WC-Co edge can liberate binder fines into the breathing zone. Pre-treatment: Confirm extraction and air monitoring against cobalt exposure limits before production carbide strip..

Chromium-bearing CrN or CrTiAlN stacks where hexavalent chromium rules may apply downstream — Chromium (VI) general-industry rules still govern process dust and waste classification when chromium chemistry is in the film, even when the strip method is dry laser. Pre-treatment: Review the applicable chromium (VI) standard before scaling CrN strip cells..

Sources(1 reference)
  1. 29 CFR 1926.102 — Eye and Face Protection osha.gov (opens in new tab) — Eye and face protection rules apply in Class 4 laser strip cells before energy rises on production inserts

Engineered wear films, not corrosion or shop grease

Hard coatings form as engineered Physical Vapor Deposition or Chemical Vapor Deposition wear layers rather than as rust or shop grease. That layered structure is what stripping trials on CrN-coated high-speed steel describe, and the coating family spans silver-gray CrN near 2000-2500 HV, hotter TiAlN and AlTiN cutting films, and thin low-friction DLC carbon skins in the 1.5-10 um band.

Sources(1 reference)
  1. Stripping of CrN from CrN-coated high-speed steels sciencedirect.com (opens in new tab) — Stripping trials on CrN-coated high-speed steel describe the layered wear-film structure

Fast heating breaks the film off the bond line

Short pulses heat the dark nitride or carbon film faster than the tool body can carry the heat away, so the film expands and breaks free at the coating-substrate bond rather than dissolving in a bath. Segmental laser-stripping work on monolithic cutting tools documents that same bond-line failure across coated inserts.

Sources(1 reference)
  1. Segmental Laser Stripping of Thin Coatings on Monolithic Cutting Tools mmscience.eu (opens in new tab) — Segmental laser-stripping work on monolithic cutting tools documents bond-line failure across coated inserts

No shop-wide infrared band covers every coating grade

Hard-coating strip numbers stay chemistry- and wavelength-specific, so shops lack one typed infrared production band for hard coatings. Aggregated coupon work on CrTiAlN and TiAlN spans about 2.71 to 3.38 J/cm2 at 355 nm ultraviolet on carbide, while typed floors and ceilings for every CrN or TiAlN grade at shop infrared remain scarce, so this page keeps those fields empty instead of inventing a single safe energy range.

Sources(1 reference)
  1. Laser coating removal: Topics by Science.gov (aggregates CrTiAlN excimer and TiAlN DPSS UV work) science.gov (opens in new tab) — Aggregated CrTiAlN excimer and TiAlN DPSS UV coating-removal work spans about 2.71 to 3.38 J/cm2 on carbide

Class 4 cell rules plus cobalt and chromium exposure limits

Tool-coating strip cells still fall under Class 4 laser safe-use rules, airborne exposure tables for cobalt and chromium metals, and federal Chromium (VI) process controls when chromium chemistry is in the film. Those strip cells also need nitride and carbon dust captured at the head, with WC-Co fines treated as cobalt-bearing particulate rather than generic shop dust.

Sources(3 references)
  1. ANSI Z136.1 — Safe Use of Lasers webstore.ansi.org (opens in new tab) — Safe use of lasers for industrial strip and cleaning cells
  2. Cal/OSHA Title 8 §5155 — Airborne Contaminants (Table AC-1) dir.ca.gov (opens in new tab) — California airborne limits covering cobalt and chromium metals
  3. 29 CFR 1910.1026 — Chromium (VI) osha.gov (opens in new tab) — Federal Chromium (VI) standard for general industry

Carbide and tool steel carry the same films differently

The same wear chemistry forms on different hosts, and cemented carbide carries heat differently than tool steel because cobalt binder sets a tighter exposure story than carbon steel. That host split shows up in the coupon record too, since multiparameter nanosecond strip work on AlTiN and DLC C publishes a wide tool-steel band, so the rows keep wavelength-named coupon numbers instead of one invented shop figure.

SubstrateAblation threshold (J/cm²)Substrate damage (J/cm²)Process windowRegime
Cemented carbide (WC-Co) with TiAlN wear film2.71–3.383.38–3.382.71–3.38×355 nm DPSS UV coupon removal band for 1.5 um TiAlN on WC-Cosublimation-ablation
Tool steel with AlTiN or DLC C film2.9–2929–292.9–29×1064 nm, 120 ns multiparameter strip span for AlTiN and DLC Csublimation-ablation
Sources(1 reference)
  1. Investigation of Multiparameter Laser Stripping of AlTiN and DLC C Coatings pmc.ncbi.nlm.nih.gov (opens in new tab) — 1064 nm, 120 ns strip work spanning about 2.9-29 J/cm2 on AlTiN and DLC C ties the tool-steel band to published coupons

Coating chemistry sets the removal band, not one recipe

Chemistry, thickness, and the substrate under the film decide how a hard coating leaves under pulsed light, and peer-reviewed stripping work on functional coatings shows that removal stays chemistry-specific rather than following one infrared rust recipe. A number copied from another job cannot replace those three facts.

ParameterValue
Functional coating laser stripPeer-reviewed stripping work shows chemistry-specific removal rather than one infrared rust recipe
Typical PVD thicknessWear films commonly sit in the low-micrometer band on cutting tools before strip
Host sensitivitySubstrate choice still changes how a thin wear film leaves under pulsed light
Sources(1 reference)
  1. Laser stripping of functional coatings on glass fiber reinforced plastic substrate, Applied Optics, 2022 doi:10.1364/AO.465836 (opens in new tab) — Peer-reviewed laser stripping of functional coatings on fiber-reinforced plastic substrates shows chemistry-specific removal

One preset across every coating chemistry fails often

Wrong energy on the wrong host leaves melted binder, rounded edges, or leftover film islands that spoil re-coat. Wrong energy on DLC can also drive structural change in the carbon film before the substrate clears, which Raman studies on ultrafast-ablated DLC characterize directly, so copying a rust preset onto a coated insert fails often.

ConditionConsequence
Infrared energy pushed past the film into cobalt-bonded carbide[1]Binder smears or edge melt appears while residual coating islands still stick in low spots.
One paint or rust preset applied across CrN, TiAlN, and DLC grades[1]One chemistry clears while another burns the substrate, leaves unbroken film, or drives unwanted structural change in DLC.
Sources(1 reference)
  1. Raman Studies of Structural Changes in Diamond-like Carbon Films on Si Induced by Ultrafast Laser Ablation jlps.gr.jp (opens in new tab) — Raman studies of ultrafast-ablated DLC characterize structural change risk directly

A calo crater settles thickness disputes before strip

Before strip, the traveler or a calo crater shows the chemistry and approximate thickness. After strip, bright magnification shows whether residual gold, gray, or black film still covers the cutting edge, and PPE criteria still apply during that coated-tool inspection.

  • Pre-cleaning assessment: Record coating type, host (HSS versus WC-Co), and nominal thickness from the traveler or a calo test before setting energy.
  • Bright-field edge microscopy: Accept only when residual TiN gold, CrN gray, or DLC black film is gone from the scanned land.
  • Calo / ball-crater check when thickness disputes remain: Confirm complete film removal through the crater before releasing the tool to re-coat.
Sources(1 reference)
  1. 29 CFR 1926.95 — Criteria for Personal Protective Equipment osha.gov (opens in new tab) — PPE criteria still apply during coated-tool laser strip inspection

Nitride and carbon dust replace a chemical bath

Pulsed strip generates metal-nitride particulate from CrN, TiAlN, and AlTiN films and carbon dust from DLC, and HEPA capture at the head handles that particulate load on continuous tool-cell work. Metal-particulate exposure in the breathing zone still follows a federal air-contaminant limits table.

Sources(1 reference)
  1. 29 CFR 1910.1000 Table Z-1 — Limits for Air Contaminants osha.gov (opens in new tab) — Federal air-contaminant limits table still frames metal-particulate exposure from nitride and carbon dust

Re-coat follows edge and adhesion checks, not time

Hard coatings do not form again in air the way rust does, so the next step after those hard coatings leave is usually edge inspection, re-sharpening, and a planned re-coat cycle under a hexavalent chromium standard when chromium chemistry was in the film. Regenerated lots still need adhesion checks before production cutters leave.

  • Recontamination susceptibility: Wear films do not re-grow at room temperature; the risk is leftover coating islands that spoil re-coat, not flash rust of the film itself.
  • Post-removal surface readiness: Laser-cleared tools are ready for re-coat only after edge integrity and adhesion checks on the regenerated lot.
Sources(1 reference)
  1. 8 CCR §5206 — Cal/OSHA Hexavalent Chromium Standard (General Industry) dir.ca.gov (opens in new tab) — Hexavalent chromium standard governs re-coat planning when chromium chemistry was in the stripped film
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