Metal Surface Treatment Guide from an ISO 9001 Certified Precision Machining Facility
Why Surface Treatment Matters in CNC Machining
In precision manufacturing, surface finishing is not only about aesthetics — it is about performance, durability, and process control.
At Bergek CNC, an ISO 9001 certified facility with 5-axis machining expertise, the choice of finishing process directly affects:
Corrosion resistance – how parts perform in real environments
Durability – resistance against scratches, abrasion, and chemicals
Aesthetics – brand perception and product value
Manufacturability – consistency from prototypes to production runs
Common questions we hear: “Is anodizing enough for outdoor use?” or “Should I switch from painting to powder coating for better durability?”
The answer requires both engineering judgment and quality system assurance.
Comparison of Common Surface Treatments
Process
Appearance
Durability
Typical Thickness
Standards
Applications
Limitations
Anodizing (阳极氧化)
Metallic finish, multiple colors
Excellent corrosion resistance, hardness up to ~300 HV
5–25 μm (Type II), 25–100 μm (Type III)
ISO 7599, MIL-A-8625
Electronics housings, aerospace components
Color consistency can vary across alloys and batches
Powder Coating (粉末喷涂)
Smooth, uniform, rich colors
500–1,000 hrs salt spray (ASTM B117, lab); field performance depends on UV & wear
60–120 μm
ISO 8130, ASTM D3359
Automotive, appliances, enclosures
Not ideal for fine features; coating buildup possible
Painting (喷漆)
Flexible colors, supports patterns
100–250 hrs salt spray typical (ASTM B117); limited scratch resistance
15–25 μm
ASTM D3359, ISO 2409
Prototypes, short-life consumer goods
Inconsistent in mass production, prone to chipping
Clear Coat (清漆保护层)
Transparent gloss, keeps natural metal
50–150 hrs salt spray (ASTM B117, indoor use); outdoors<6 months without UV blockers
10–20 μm
ASTM D3363
Display parts, cosmetic panels
Limited corrosion protection; mainly aesthetic
Engineer’s Notes
Anodizing → Excellent for 6061/5052 alloys; poor results on high-silicon die-cast aluminum (ADC12, A380).
Powder Coating → More durable than wet paint, but design must avoid coating in threads and tight clearances.
Painting → Fast and cheap, but adhesion weaker and wear resistance lower than powder coating.
Clear Coat → Serves mainly as a cosmetic sealer; should not be relied upon for corrosion-critical applications.
Always evaluate finishing options in both lab tests and real-world conditions.
Other Advanced Finishes
Beyond the common methods, Bergek CNC also provides:
Plating (电镀) → Nickel/chrome plating for wear resistance; zinc plating for corrosion protection.
Electropolishing (电解抛光) → Produces ultra-smooth surfaces for medical, semiconductor, and food-contact parts.
Real Customer Case
An automotive customer initially specified wet painting for enclosures.
In lab tests: failures after ~250 hrs salt spray (ASTM B117).
After switching to powder coating: passed 1,000 hrs lab test and showed significantly fewer field failures.
Instead of marketing claims, we track results through standardized testing and field performance monitoring.
FAQ: Common Engineering Questions
Q1: Is powder coating always more durable than painting?
Yes, under lab tests: powder coating typically 60–120 μm, 500–1,000 hrs salt spray; painting 15–25 μm, 100–250 hrs. Real-world performance depends on UV, abrasion, and environment.
Q2: Can all aluminum alloys be anodized?
No. 6061/5052 anodize well; high-silicon die-cast alloys yield uneven finishes.
Q3: How long does clear coat protection last?
Typically 6–12 months indoors; outdoor use without UV blockers may drop below 6 months. Specialized coatings can extend service life.
Q4: What does ISO 9001 ensure in surface finishing?
ISO 9001 does not define finishing quality itself. It ensures process consistency:
- Documented coating thickness checks
- Batch traceability & QC reports
- Periodic adhesion/hardness tests per ASTM/ISO standards
Q5: Which finishes are FDA-compliant for food or medical parts?
Electropolishing and specific passivation processes are suitable for stainless steel components, validated with FDA and ISO 13485 standards.
Bergek CNC’s Approach
Engineer-Verified DFM Reviews – Ensuring feasibility and performance.
Material & Process Guidance – Helping clients balance cost, durability, and compliance.
Consistency Control – ISO 9001 systems ensure every batch matches approved specs.
We are not just a machining vendor — we are your engineering partner for reliable manufacturing.
Final Thought
The right surface finish goes beyond looks. It defines durability, reliability, and trust.
With ISO 9001 certified quality management and 5-axis machining expertise, Bergek CNC helps clients across automotive, aerospace, medical, and consumer industries achieve consistent, reliable finishing results.
