Engineering reference · Surface finishing
Surface Finish Guide for Precision Manufacturing
Select the right finish for corrosion protection, wear resistance, conductivity, appearance, and dimensional control—before your parts enter production.
12+
Common finish processes compared
0.02–0.05 mm
Typical added thickness per side for heavier finishes
3 checks
Material, tolerance, and post-finish quality review
Design focus
Treat finishing as part of the engineering specification—not only the final cosmetic step.
Start with the application
Before you specify a finish
The correct process depends on how the part will operate, assemble, and age. Review the material, environment, appearance, and tolerance requirements together before finalizing your CAD files.
Engineering module 01 Do precision mating surfaces need masking? +
Yes, when a surface must remain within a high-tolerance fit. Bearing bores, dowel pin holes, and mating faces can fall out of tolerance when anodizing or plating builds up on them. Specify masking for critical features so the finished part fits correctly upon arrival.
PartsMake reviews drawings and CAD files to identify features that require protection during the chemical or coating process.
Engineering module 02 How should film thickness be compensated? +
Most finishes add material to the surface. Passivation has negligible dimensional impact, while hard coat anodizing and heavier plating can add 0.02 mm to 0.05 mm or more per side. Account for this buildup in pre-machining dimensions when tolerances are tight.
When you upload files to PartsMake, the engineering review checks whether the specified tolerances accommodate the required finish.
Process selection matrix
Surface finish comparison
Use material compatibility, corrosion resistance, hardness, film thickness, and masking requirements to narrow the process for your part.
| Finish process | Material compatibility | Corrosion resistance | Hardness | Typical thickness | Masking required |
|---|---|---|---|---|---|
| Clear Anodizing | Aluminum | Moderate | Moderate | 5–25 µm | Yes |
| Hard Coat Anodizing | Aluminum | High | Very high | 25–100 µm | Yes |
| Chem Film (Chromate) | Aluminum | High | Low | < 1 µm | No |
| Passivation | Stainless steel | Very high | N/A | Negligible | No |
| Electropolishing | Stainless steel | High | N/A | Negligible | No |
| Black Oxide | Steel | Low | Low | < 1 µm | No |
| Electroless Nickel | Steel, aluminum, copper | Very high | High | 5–50 µm | Yes |
| Powder Coating | Most metals | High | High | 50–150 µm | Yes |
| Bead Blasting | Most metals | N/A | N/A | N/A | Yes |
| Laser Marking | Most metals, plastics | N/A | N/A | N/A | No |
| Zinc Plating | Steel | High | Low | 5–25 µm | Yes |
| Chrome Plating | Steel, copper | Very high | Very high | 10–50 µm | Yes |
Thickness and masking requirements vary with the selected specification, geometry, and supplier process. Confirm critical dimensions during engineering review.
Application guide
Match the finish to the operating requirement
Harsh environments
For moisture, chemicals, or salt spray, consider Hard Coat Anodizing for aluminum or Electroless Nickel for steel. Passivation is the standard stainless steel process for removing surface contaminants and helping prevent oxidation.
High-wear applications
Gears, shafts, and sliding mechanisms benefit from durable surface layers. Hard Coat Anodizing creates a ceramic-like surface on aluminum, while Electroless Nickel provides wear resistance and uniform coverage across complex geometries.
Aesthetic requirements
For user-facing components, Bead Blasting creates a consistent matte finish that hides machining marks. Powder Coating adds a tough shell with a wide range of colors and textures.
End-to-end coordination
Surface finishing managed with your manufacturing workflow
PartsMake coordinates finishing internally or through a vetted supply chain, reducing the effort of managing multiple vendors.
Manufacturing review
Analyze CAD and drawings for material, finish, and tolerance compatibility.
Process coordination
Track CNC machining through finishing while managing masking and thickness compensation.
Quality verification
Verify dimensions after finishing to ensure parts meet your specifications.
Start with engineering review
Avoid costly finish-related revisions
Surface finish decisions affect budget, lead time, assembly, and part performance. Upload your CAD files and drawings for a manufacturing review.
- ●Review material, tolerances, masking, and finish requirements.
- ●Receive a DFM report and formal quotation from the engineering team.
- ●Coordinate machining and finishing through one manufacturing workflow.
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