1. Basic Information
This technical data sheet specifies the standard parameters, performance indicators, application scope and related notes of low temperature black chrome plating process for ball screw. It is applicable to the production, inspection and selection of precision mechanical components, optical parts and other ball screw products requiring black chrome plating protection and decoration.
Plating Type: Low Temperature Electrolytic Black Chrome Plating (Cr + Cr₂O₃ composite coating)
Applicable Industry: Precision Manufacturing, Optical Engineering, Automotive, Aerospace, Medical Devices, Electronic Components
2. Basic Process Parameters
|
Item |
Specification |
Unit |
|
Plating Type |
Low Temperature Electrolytic Black Chrome Plating (Cr + Cr₂O₃ composite coating) |
— |
|
Operating Temperature |
-10 ~ +25 (Typically controlled at 0 ± 5) |
°C |
|
Plating Bath System |
Trivalent Chromium (Preferred) / Hexavalent Chromium |
— |
|
Bath pH |
2.0 ~ 3.5 |
— |
|
Cathode Current Density |
15 ~ 50 |
A/dm² |
|
Plating Time |
3 ~ 15 (depending on required thickness) |
min |
|
Anode Material |
Lead‑tin Alloy / Graphite / Special Inert Anode |
— |
3. Coating Properties
|
Item |
Standard Value |
Test Method |
|
Coating Thickness |
1.0 ~ 3.0 (Typical: 1.5 ~ 2.0) |
μm |
|
Microhardness |
300 ~ 600 |
HV |
|
Adhesion |
Grade 1, no peeling, no blistering |
ASTM D3359 Cross‑cut Test |
|
Appearance & Gloss |
Uniform matte black / semi‑matte black; Gloss < 15 GU |
Visual inspection, gloss meter |
|
Surface Roughness Ra |
0.2 ~ 0.8 (depending on substrate finish) |
μm |
|
Heat Resistance |
Stable ≤ 300 °C without discoloration; short‑term heat resistance up to 480 °C |
Thermal cycling test |
4. Corrosion & Wear Resistance
|
Item |
Performance |
Test Condition |
|
Neutral Salt Spray (NSS) |
> 200 hrs without red rust; > 400 hrs with sealing treatment |
ASTM B117 |
|
Wear Resistance |
Excellent, better than black oxide and conventional nickel plating |
Dry sliding / Taber abrasion test |
|
Chemical Resistance |
Good resistance to weak acids, alkalis, oils and solvents; limited resistance to strong oxidizing acids |
Immersion test |
5. Dimensional & Thermal Characteristics
|
Item |
Performance |
|
Thermal Deformation |
Negligible, no annealing or thermal expansion (low temperature process ensures no thermal damage to workpieces) |
|
Dimensional Accuracy |
Ultra‑thin uniform coating, minimal influence on workpiece dimensions, suitable for parts with micron‑level tolerance |
6. Applicable Base Materials & Main Applications
6.1 Applicable Base Materials
Steel, stainless steel, aluminum alloy, copper alloy, and other common metal substrates.
6.2 Main Applications
• Precision transmission components: ball screws, linear guides, spline shafts (corrosion protection + precision retention)
• Optical and semiconductor parts: light‑shielding components, precision instrument parts (light absorption + cleanliness)
• Automotive and aerospace parts: interior components, sensors, instruments (matte black appearance + durability)
• Medical devices: precision casings, surgical instruments (corrosion resistance + biocompatibility)
• High-end hardware: bathroom accessories, watches, precision hardware components (texture + wear resistance)
7. Advantages
• Low temperature operation avoids thermal deformation, annealing and softening of workpieces, ensuring the dimensional precision of high-precision components.
• Ultra-thin and uniform coating, with minimal impact on the original dimensions of workpieces, suitable for parts with strict tolerance requirements.
• Excellent corrosion resistance and wear resistance, far superior to conventional black oxide and ordinary nickel plating processes.
• Uniform matte black appearance, good light absorption performance, suitable for optical and precision equipment requiring low reflectivity.
• Wide applicability, compatible with various common metal substrates, meeting the needs of different industrial fields.