Common Surface Treatments in CNC Machining: How to Choose Between Sandblasting, Anodizing, and Plati

3-Minute Guide to Selecting Surface Finishes While Avoiding 90% of Post-Processing Issues

Surface treatments account for 15-35% of total part costs in precision machining

With experience from 200+ metal finishing projects, our technical team reveals engineering-driven selection strategies for these three mainstream processes.

I. Core Technical Comparison Matrix

II. Process Characteristics Deep Dive

1. Sandblasting: Rapid Functional Surface Preparation

Key Benefits:

Enhanced cleanliness: Achieves Sa 2.5 surface standard

Stress relief: Creates 0.05-0.1mm compressive stress layer

Matte finishes: Controlled roughness Ra 1.6-6.3μm

Common Mistakes:

Using glass beads on stainless steel causing embedded contamination

Over-blasting aluminum leading to fatigue strength reduction

Our Innovations:
✅ Precision ceramic media (#220-#800 grit options)
✅ 3D adaptive robotic blasting systems

2. Anodizing: Comprehensive Protection for Aluminum

Process Tree:

Technical Limitations:

Aluminum with >5% copper content causes color inconsistency

Allow 0.02-0.05mm expansion for threaded components

Success Case:
Drone gimbal bracket using hard anodizing:

3x wear resistance improvement

15% weight reduction vs plated steel

3. Plating: Precision Functional Coatings

Coating Selection Guide：

Critical Controls:

Perfect degreasing (contact angle <5°)

Coating thickness variation ≤±2μm

200℃×4h dehydrogenation for embrittlement-sensitive parts

III. Decision Flowchart: 5 Steps to Optimal Selection

Functional Needs:

Corrosion protection → Anodizing/Plating

Aesthetics → Sandblasting/Colored anodizing

Special properties → Hybrid processes (e.g., sandblast + MAO)

Base Material:

Aluminum → Anodizing

Steel → Plating/Dacromet

Tolerance Limits:

Avoid anodizing if tolerance <0.05mm

Skip hard anodizing for thin walls (<1mm)

Budget Constraints:

<¥5/dm² → Sandblasting/Natural anodizing

¥10/dm² → Multi-layer plating/Special anodizing

Certifications:

Food-grade: FDA-compliant anodizing

Military: MIL-A-8625 Type III

Medical: ISO 13485 compatible processes

• Our Technical Advantages:
  ✅ Surface failure analysis lab (SEM/EDS equipped)
  ✅ Specialized capabilities:
  　- Conductive aluminum oxidation (<0.1Ω)
  　- Fingerprint-resistant stainless steel plating
  ✅ 48-hour rapid prototyping

  FAQ:

Q: Can 304 stainless steel be anodized?

A: Requires specialized electrolysis (+40% cost). Recommend PVD coatings instead.

Q: Is plating after sandblasting feasible?

A: Requires ultrasonic cleaning to prevent blistering from residual media.

Q: How to ensure black anodizing colorfastness?

A: Use organic dyes + medium-temperature sealing (ΔE<1.5 after 1000h UV testing).