In CNC machining, cutting metal is just the beginning. The right post-machining finish can enhance part performance, durability, appearance – and even regulatory compliance. Whether you’re manufacturing aerospace brackets, medical housings, or industrial enclosures, surface finish matters.
So how do you know which finish is right for your project? Let’s break it down.
Why Post-Machining Finishes Matter
A raw machined part may meet dimensional specs, but post-processing adds that final layer of functionality or protection. The finish you choose can:
- Prevent corrosion
- Improve wear resistance
- Increase biocompatibility (for medical parts)
- Enhance electrical conductivity
- Meet cosmetic or branding goals
At MDA Ltd, we routinely advise clients on post-machining treatments based on material, use case, and performance criteria.
Common Types of Post-Machining Finishes
1. Anodizing (Aluminum Parts)
Best for: Aerospace, electronics, automotive
Benefits:
- Corrosion resistance
- Electrical insulation
- Available in colors (for part coding or branding)
Types:
- Type II: Cosmetic and corrosion protection
- Type III (Hardcoat): For wear and abrasion resistance
2. Passivation (Stainless Steel)
Best for: Medical devices, food-grade equipment
Benefits:
- Removes surface contaminants
- Restores natural oxide layer
- Enhances corrosion resistance without altering dimensions
3. Powder Coating or Painting
Best for: Consumer-facing parts, enclosures
Benefits:
- Thick, uniform coverage
- Wide color range
- Durable, chip-resistant finish
Tip: Great for branding or weather resistance.
4. Electropolishing
Best for: Medical, semiconductor, food processing
Benefits:
- Ultra-smooth surface
- Removes microscopic burrs
- Increases corrosion resistance and cleanliness
5. Zinc or Nickel Plating
Best for: Steel parts requiring corrosion resistance
Benefits:
- Thin conductive layer
- Often used in electrical components
- Enhanced wear protection
6. Bead Blasting or Tumbling
Best for: Surface uniformity, deburring
Benefits:
- Smooth matte finish
- Ideal before painting or anodizing
- Removes tool marks or burrs
Choosing the Right Finish: Key Questions to Ask
- What environment will the part operate in?
- High humidity? Choose anodizing or passivation.
- High-wear? Go with hardcoat anodizing or plating.
- Does the part require biocompatibility?
- Medical parts may require electropolishing or passivation.
- Is appearance important?
- Consider powder coating, painting, or color anodizing.
- Is electrical conductivity needed?
- Avoid anodizing; choose plating instead.
MDA’s Approach to Finishing
At MDA Ltd, we don’t just machine parts – we deliver them ready for real-world application. That includes working with trusted finishing partners across Canada to apply finishes that meet your mechanical, cosmetic, and regulatory needs.
From recommending the ideal surface treatment to coordinating certifications (RoHS, REACH, ASTM, MIL-SPEC), we ensure your parts are finished to spec and on schedule.
Final Thoughts
Choosing the best post-machining finish isn’t just about aesthetics – it’s about matching materials, environments, and performance goals. Whether you need a simple bead-blast or a hard-anodized, biocompatible medical device, we’re here to help guide you through every layer of the process.