Thin dense chrome is the bearing industry's own coating: 2–10 µm of crack-free chromium on a raceway, harder than the steel beneath it, with lower friction and real corrosion resistance.
| Thickness | 2–10 µm (typically 3–5 µm on raceways) |
|---|---|
| Hardness | 800–1000 HV |
| Friction | 0.10–0.20 against steel — lower than hardened steel on steel |
| Max service temperature | ≈300 °C |
| Corrosion | Good — a crack-free barrier, unlike conventional hard chrome |
| Effect on dimension | 4–20 µm across a diameter at 2–10 µm per surface |
| Hydrogen embrittlement | Lower risk than hard chrome, but a post-bake is still specified |
| Typical use | Raceways, rolls, hydraulic rods, printing and paper machinery |
Conventional hard chrome is deposited at 20–100 µm and is micro-cracked — the cracks are what allow thick deposits without spalling, but they also give corrosion a path to the steel. Thin dense chrome is deposited at 2–10 µm with a modified bath that produces a crack-free structure. It is thinner, harder for its thickness, and it actually seals the surface.
For a bearing raceway, that combination is useful: the coating is hard enough to resist wear, smooth enough not to disturb the contact, thin enough to leave the geometry essentially unchanged, and continuous enough to protect the steel underneath.
| Property | Thin dense chrome | Hard chrome | DLC |
|---|---|---|---|
| Thickness | 2–10 µm | 20–100 µm | 1–3 µm |
| Hardness | 800–1000 HV | 700–1000 HV | 2000–4000 HV |
| Structure | Crack-free | Micro-cracked | Amorphous |
| Corrosion | Good | Poor through cracks | Barrier only |
| Max temp | ≈300 °C | ≈300 °C | ≈300 °C |
| Cost | Moderate | Moderate | High |
Wear and corrosion protection on the rolling surface.
Read →Marginal lubrication at high speed.
Read →When friction must be lower still.
Read →When the requirement is corrosion of a housing, not wear of a raceway.
Read →No. Decorative chrome is a thin layer over nickel for appearance. TDC is a functional chromium deposit specified for hardness, friction and corrosion on working surfaces.
To the rings, yes, before assembly. The bearing is disassembled, the rings are plated and baked, and the bearing is reassembled and re-greased. It is not a treatment for an assembled unit.
It can, like any electroplating process on hardened steel. A post-plate bake at 190–200 °C for several hours is standard, and the specification should require it.
Yes — by 4–20 µm across a diameter for a 2–10 µm deposit. Either coat before final grinding or reduce the pre-grind dimension to compensate.
Model numbers, quantities and the application — we reply with brand options, price and lead time within 30 minutes on working days.