In the world of medical device manufacturing, details matter. And few details are as critical - yet easy to get wrong - as anodizing thickness. When the requirement is a precise 5μm ±0.2μm, that tolerance becomes more than just a number. It affects product reliability, safety, and regulatory compliance.
Here's a look at the common problems manufacturers face when meeting this strict spec - and how to overcome them.
1. Coating Thickness Out of Tolerance
This is the most obvious issue: the anodized layer ends up thinner than 4.8μm or thicker than 5.2μm.
What causes it?
Inconsistent current density during the anodizing process
Poor temperature control in the electrolyte bath
Improper part positioning or uneven current flow
Material batch differences that change surface reactivity
How to avoid it:
Use a constant-current power supply with fine control
Keep bath temperatures within a tight ±1°C window
Use consistent fixturing and ensure solid electrical contact
Run small-scale tests on each aluminum batch before full production
2. Uneven Coating or White Spots on the Surface
Even if the average thickness is okay, localized variation or discoloration can still occur.
Common reasons:
Poor pre-treatment or residual contaminants
Sharp corners or complex geometries creating "dead zones"
Parts processed in batches with inconsistent exposure
Best practices:
Improve degreasing and acid cleaning to ensure a clean, uniform surface
Rotate parts during anodizing or use tailored multi-point electrode setups
Split complex parts into smaller, better-controlled batches
3. The Thickness Is Right - But Performance Is Poor
This is perhaps the most frustrating scenario. Your film is 5μm ±0.2μm, but adhesion is weak or corrosion resistance fails.
Likely culprits:
Porous or loosely packed oxide layers
Incomplete sealing post-anodizing
Use of general-purpose (non-medical-grade) anodizing chemicals
What helps:
Choose medical-grade anodizing processes (compliant with ISO 10993, ASTM F86)
Invest in high-quality additives that improve film density
Control sealing time and temperature to ensure full pore closure
Final Thoughts
A precise anodizing spec like 5μm ±0.2μm isn't just a challenge - it's a quality benchmark. Meeting it consistently requires more than good equipment. It demands tight process control, skilled technicians, and a deep understanding of material behavior.
If your application involves mission-critical medical parts, we're here to help. Our team is experienced in meeting tight anodizing tolerances and supporting rapid prototyping with full documentation and traceability.
