Diamond-like Carbon (DLC)

Diamond-like carbon (DLC) deposits an ultra-hard, low-friction carbon film on parts, boosting wear resistance and lubricity on precision surfaces.

Overview

Diamond-like Carbon (DLC) is a thin, amorphous carbon coating applied by PVD/CVD processes to create an ultra-hard, low-friction surface. Typical thickness is 1–5 µm, so it adds minimal dimension while providing very high hardness, excellent sliding wear resistance, and good dry-running behavior. DLC works best on precision-finished parts where you want to extend life without redesigning the geometry.

Use DLC when your part sees abrasive wear, sliding contact, or marginal lubrication, and you need long life without galling or seizure. It is common on tools, precision mechanisms, and high-duty engine parts. Tradeoffs: coating temperatures and process chemistry limit substrate materials; sharp edges and deep blind features coat poorly; adhesion depends heavily on surface prep and base material hardness. DLC is not a fix for poor base material or bad geometry—think of it as a performance multiplier on an already sound design and finish.

Common Materials

  • Tool steel H13
  • Tool steel D2
  • Stainless steel 440C
  • Carbide (WC-Co)
  • Titanium Grade 5
  • Nitrided steel

Tolerances

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Applications

  • Carbide cutting inserts and end mills
  • Injection mold cores and slides
  • Automotive tappets and piston pins
  • Hydraulic and pneumatic valve spools
  • Pump shafts and mechanical seal faces
  • Medical instruments and surgical tools

When to Choose Diamond-like Carbon (DLC)

Choose DLC when you need very high wear resistance and low friction on a precision surface without changing part geometry. It suits hardened metallic substrates and carbide in medium to high volumes where coating cost is justified by extended life or reduced lubrication. Best for parts that can be fully finished before coating and tolerate thin, micrometer-level thickness additions.

vs TiN

Pick DLC over TiN when low friction and sliding wear performance matter more than color or lowest cost. DLC typically offers lower coefficient of friction and better performance in boundary lubrication or dry-running conditions, especially on mating precision components and cutting tools for non-ferrous materials.

vs TiAIN

Choose DLC instead of TiAlN when you are not running at very high temperatures but need low friction and excellent wear in cooler, lubricated, or intermittent-contact applications. DLC outperforms TiAlN in many sliding and non-ferrous cutting cases, but it is less suitable for continuous high-heat metal cutting where TiAlN’s oxidation resistance dominates.

vs Nitriding

Use DLC instead of nitriding when you need ultra-low friction and a thinner, more controlled surface layer on already hardened parts. Nitriding modifies the substrate and is great for bulk fatigue and wear, while DLC gives a hard, low-friction top layer that can be added after full machining and heat treatment with minimal dimensional impact.

vs Hard chrome plating

Select DLC over hard chrome when you want thinner coatings, lower friction, and to avoid hexavalent chromium and associated environmental issues. DLC provides comparable or better wear resistance with much smaller dimensional change, which helps on tight-tolerance precision components and fine features.

vs Uncoated (base material only)

Specify DLC when your current base material and geometry meet strength and stiffness needs but wear or galling are limiting life. DLC lets you boost wear resistance, reduce friction, and often eliminate external lubrication without moving to more expensive bulk materials or redesigning the part.

Design Considerations

  • Define where coating is required and where masking is needed; provide drawings with clearly marked coated and uncoated areas
  • Finish all critical surfaces before DLC; typical Ra should be ≤0.2–0.4 µm for best adhesion and low friction
  • Account for coating thickness (1–5 µm) on tight fits; avoid designing clearances below a few microns without discussing with the coater
  • Use small edge radii instead of sharp corners to improve coating adhesion and coverage and reduce risk of chipping
  • Avoid very deep, narrow blind holes and slots for functional coating; line-of-sight access is needed for uniform DLC deposition
  • Specify substrate hardness and prior heat treatment; DLC adheres best to hardened steels and carbide, and process temperature must not affect your base properties