TOSTA Precision Springs & Retaining Rings

Spring Coatings & Advanced Surface Treatments

Engineered corrosion protection, wear resistance, and aesthetic finishing for high-performance industrial springs.

Surface Treatment Process Portfolio

Surface treatments extend spring working life in harsh atmospheric, corrosive chemical, or marine conditions.

Electrophoretic Deposition (E-Coat / ED)

Waterborne epoxy resin electro-coating delivering pinhole-free coverage, zero hydrogen embrittlement risk, and uniform film thickness even on tight inner coils.

Film Thickness: 15–25 μm
Salt Spray (NSS): 500–1000h (ASTM B117)
Color / Finish: Black / Dark Gray
Max Temp: ≤ 150°C
Recommended Environment: Automotive chassis / General industrial machinery

Electro-Galvanized Zinc (Cr³⁺ Passivation)

Bright electrolytic zinc plating with trivalent blue/iridescent passivate, offering sacrificial cathodic protection at economical cost.

Film Thickness: 8–15 μm
Salt Spray (NSS): 48–96h (ASTM B117)
Color / Finish: Blue-White / Iridescent
Max Temp: ≤ 120°C
Recommended Environment: Indoor enclosures / Dry machinery mechanisms

Electroless Nickel Plating

High-hardness uniform nickel-phosphorus alloy deposit providing exceptional wear resistance, lubricity, and conductivity.

Film Thickness: 5–20 μm
Salt Spray (NSS): 200–500h (ASTM B117)
Color / Finish: Silver White Metallic
Max Temp: ≤ 400°C
Recommended Environment: Electronics / Medical devices / Optical tooling

Dacromet® / Geomet® (Zinc Flake Coating)

Non-electrolytic zinc/aluminum flake protective coating with zero risk of hydrogen embrittlement. Top-tier salt spray performance.

Film Thickness: 8–15 μm
Salt Spray (NSS): 500–2000h (ASTM B117)
Color / Finish: Silver Gray / Black
Max Temp: ≤ 300°C
Recommended Environment: Automotive underbody / Offshore marine / Wind turbines

Manganese / Zinc Phosphating

Chemical conversion coating creating micro-crystalline phosphate layer. Superior oil retention and friction reduction.

Film Thickness: 3–8 μm
Salt Spray (NSS): 24–72h (with rust-preventative oil)
Color / Finish: Medium Gray / Charcoal
Max Temp: ≤ 200°C
Recommended Environment: Internal engine/gearbox oil-lubricated systems

Black Oxide (Hot Chemical Bluing)

Controlled alkaline oxidation forming magnetite (Fe₃O₄) surface layer with zero dimensional change, finished with rust-inhibiting oil.

Film Thickness: 1–3 μm
Salt Spray (NSS): 4–24h
Color / Finish: Deep Matte Black
Max Temp: ≤ 150°C
Recommended Environment: Precision fixtures / Stamping tools / Optical parts

Engineering Finishing Recommendations

  • • Outdoor, automotive underbody, or subsea: Dacromet® / Geomet® provides supreme salt spray protection with zero hydrogen embrittlement.
  • • General industrial automation: Electrophoretic deposition (ED) provides optimal cost-to-performance.
  • • Electronics & electrical contacts: Electroless nickel plating ensures electrical conductivity and low contact resistance.
  • • Tight dimensional pockets: Black oxide adds corrosion resistance without changing critical wire dimensions (< 1 μm).
Consult Finishing Specialist

Need Surface Treatment Advice for Severe Environments?

TOSTA application engineers can specify optimal finishes to pass your salt spray, cyclic corrosion, or thermal shock tests.

Contact Engineering Team Mr. Wang +86 130-1246-1618