03 / Our Solution
Using our black oxide finishing process — a chemical conversion coating technology that forms a uniform oxide layer on steel surfaces — we improved corrosion resistance and surface stability while minimizing dimensional impact on precision fasteners.
Process Adjustments
Precision-controlled black oxide conversion process
The black oxide process parameters were optimized to ensure uniform oxide layer formation while maintaining thread dimensions and mating accuracy.
Surface preparation optimization
Controlled pre-treatment procedures were applied to improve surface activation and ensure consistent black oxide layer formation across each fastener.
Batch Quality Verification
Sampling inspections were conducted to verify:
- Black oxide layer consistency
- Thread dimensional stability
- Surface appearance uniformity
Project Results
| Metric | Before | After Chiheng Solution | Improvement |
| Dimensional change after finishing | ~5–8μm | <2μm | ~70% reduction |
| Salt spray resistance | Rust visible at 24 hours | No rust after 96 hours | 4× improvement |
| Thread assembly performance | Occasional fitting issues | 100% assembly pass | Improved reliability |
The same controlled black oxide process can also support precision gear applications requiring dimensional stability and corrosion protection. See our precision gear black oxide finishing case study.
