How to Prevent Rust on CNC Beds and Ways in Humid Environments

PFT, Shenzhen

Abstract

High humidity accelerates corrosion on CNC machine beds and ways, leading to reduced precision, increased maintenance costs, and shortened equipment lifespan. This study investigates protective strategies against rust formation under humid conditions. Methods include controlled-environment exposure experiments on steel bed samples, comparative testing of protective coatings, and evaluation of lubrication practices. Results indicate that combination treatments—anti-corrosion coatings with periodic lubricating film application—significantly reduce oxidation rates compared to untreated surfaces or single-method treatments. Statistical analysis shows up to 85% reduction in rust formation after 90 days in 85% relative humidity. Findings highlight practical measures for prolonging CNC machine life and maintaining operational precision in humid production environments.

1. Introduction

CNC machines are widely used in precision manufacturing, where the integrity of beds and ways directly affects machining accuracy. High ambient humidity, particularly in tropical or poorly ventilated regions, accelerates corrosion on exposed steel surfaces. Rust formation results in:

• Uneven wear

• Increased friction

• Potential machine downtime

While routine maintenance includes periodic cleaning and lubrication, systematic evaluation of multi-layer protective strategies in humid environments is limited. This study addresses that gap through controlled experiments and comparative analysis.

2. Methodology

2.1 Experimental Design

Steel samples representing typical CNC bed and way materials (Hardened Steel, 45# Steel) were prepared with identical surface finishes (Ra 0.8 μm). Samples were divided into four treatment groups:

1. Control: Untreated

2. Lubrication only

3. Coating only (commercial anti-corrosion polymer)

4. Combined coating + lubrication

All treatments were applied under standardized procedures to ensure reproducibility.

2.2 Environmental Exposure

Samples were placed in a climate chamber maintaining 85% relative humidity at 30°C, simulating humid production environments. Exposure lasted 90 days, with inspections at 15-day intervals.

2.3 Data Collection

Measurements included:

• Rust coverage (% of surface area, digital image analysis)

• Surface hardness (HV)

• Surface roughness (Ra)

• Friction coefficient

Each experiment was conducted in triplicate.

3. Results and Analysis

3.1 Rust Formation Trends

Table 1: Rust coverage over 90 days

Figure 1 (rust progression curves) clearly shows that combined coating + lubrication maintains minimal oxidation throughout the exposure period.

3.2 Functional Surface Integrity

• Friction coefficient: Combined treatment remained within operational thresholds; untreated controls exceeded limits by Day 60.

• Surface roughness: Minimal change (<0.1 μm) for coated + lubricated samples, indicating preserved machining precision.

4. Discussion

4.1 Effectiveness of Combined Treatment

• Coating provides a physical barrier against moisture.

• Lubrication maintains a protective film, minimizing metal exposure.

• Single-method treatments reduce rust formation but are less effective in long-term high-humidity conditions.

4.2 Limitations

• Laboratory conditions may differ from real-world variations (temperature, contaminants, mechanical load).

• Long-term durability beyond 90 days requires further validation.

4.3 Practical Implications

• Implement combined coating + lubrication protocols.

• Establish inspection and reapplication schedules based on local humidity.

• Expected benefits: maintained precision, reduced maintenance, extended machine life.

5. Conclusion

Controlled experiments demonstrate that rust formation on CNC beds and ways under high humidity can be effectively mitigated using anti-corrosion coatings combined with periodic lubrication. This approach preserves surface integrity, maintains operational precision, and reduces maintenance overhead. Future research could explore long-term durability, alternative coating chemistries, and real-world operational validation.