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Salt Spray Test Duration Standards for Zn-Ni Plated Parts in MIM Industry

Views: 23 Author: Site Editor Publish Time: 2025-05-22 Origin: Site

In the Metal Injection Molding (MIM) industry, the salt spray test duration for Zn-Ni plated parts serves as the core indicator for measuring product service life. This article systematically analyzes the salt spray test standards under different working conditions by combining typical application scenarios such as aerospace, medical devices, and automotive components. It also presents comparative tables of measured data from MIMO Metal's 10+ industrial projects, providing quantitative references for product corrosion resistance optimization.

I. Industry Standards for Salt Spray Test Duration

1. Basic Protection Level (48-96 Hours)

Application Scenarios: Indoor electronic components, stationery hardware
Test Standard: ASTM B117 Neutral Salt Spray (NSS)
Plating Requirements:

Zn-Ni alloy thickness ≥8μm
Trivalent chromium passivation treatment
Acceptance Criteria: No substrate corrosion (red rust) within 96 hours

2. Industrial Protection Level (120-240 Hours)

Typical Applications: Automotive interior parts, home appliance connectors
Key Processes:

Plating thickness 12-15μm
Nickel content controlled at 13-16%
Sealant penetration treatment
MIMO Case: A brand's automotive door lock parts passed the 240h test with a 20% cost reduction.

3. Heavy Corrosion Protection Level (500-1000 Hours)

Special Requirements:

Medical implants must pass ISO 10993 biocompatibility testing
New energy vehicle components require superimposed cyclic corrosion testing (CCT)

Process Solutions:

Composite plating (Zn-Ni + Cu intermediate layer)
Nano-polymer sealing

II. 5 Key Factors Affecting Test Duration

Influence Factor	48h Scheme	240h Scheme	1000h Scheme
Plating Thickness	8μm	12μm	15μm+
Nickel Content	10-12%	13-15%	16-18%
Substrate Density	>95%	>97%	>98.5%
Post-treatment	Chromate passivation	Double-layer passivation	Nano-sealing
Test Method	NSS	AASS (Acetic Acid Salt Spray)	CCT

III. MIMO Metal's Measured Data Report

Case 1: Smart Watch Buckle (Consumer Electronics)

Requirement: No corrosion within 72h
Actual Result: First white rust appeared at 120h
Key Improvement: Adjusted plating bath temperature from 22℃ to 25℃

Case 2: New Energy Battery Bracket (Automotive)

Customer Standard: 480h CCT test
Implementation Scheme:

Electropolishing of substrate to reduce surface roughness (Ra < 0.8μm)
Adoption of pulse electroplating technology
Addition of nickel aminosulfonate additive

Final Result: Passed the test at 516h

IV. FAQ

Q: Why do parts with the same process show large test result variations?
A: Mainly affected by three factors:

Sampling location (edge vs. plane)
Temperature and humidity fluctuations in the test chamber (needs to be controlled within ±1℃)
Plating porosity (MIMO uses ISO 4524-2 standard for detection)

Q: How to reduce salt spray test costs?
Recommended Solutions:

Use continuous spraying (NSS) for the first 72h
Switch to cyclic testing (1h spraying + 1h drying) thereafter
Price comparison tips for third-party testing institutions

Conclusion

"Choosing the salt spray test duration is not about pursuing the largest value. MIMO engineers recommend: at least 240h for automotive electronics, 500h+ for medical implants, while 96h is sufficient for ordinary hardware."