Technical hub
Surface finish selection for machined parts
Use this hub to define cosmetic, protective, and process-sequence expectations for machined part finishes without over-specifying unsupported details.
Surface finish requirements often combine several different ideas: the as-machined texture on functional faces, a secondary treatment such as anodizing or plating, masking or keep-out zones, and how much dimensional change must be considered after finishing. A strong RFQ separates those points clearly.
Separate machined surface requirements from secondary finishes
A drawing may control roughness or appearance on specific machined faces while also calling for a later coating or conversion layer. Those are related but not interchangeable requirements, so they should be listed separately in the RFQ package and on the drawing.
- Mark functional sealing, sliding, optical, or datum surfaces that need special attention before finishing.
- Identify whether appearance matters on all exposed faces or only on customer-facing surfaces.
- Show which areas must stay uncoated, conductive, bondable, or dimensionally unchanged.
Describe the purpose of the finish
The selection process is stronger when the finish objective is stated plainly. Corrosion resistance, wear behavior, electrical isolation, grip, cleanability, glare reduction, and brand appearance can point to different finishing paths even when the base part geometry is the same.
- Note whether the finish is primarily functional, cosmetic, or both.
- Call out any contact surfaces, threaded features, or press fits that must be reviewed for finish impact.
- Mention if the part will be assembled with seals, adhesives, labels, or electrical contacts after finishing.
Plan for finish allowance and sequence review
Secondary processes can add thickness, change edge condition, and alter inspection timing. Instead of assuming every dimension is checked in the same state, define whether key dimensions are controlled before finish, after finish, or by a specific agreement on affected features.
- Highlight dimensions that may be sensitive to coating buildup or media exposure.
- Clarify whether masking is required on threads, bores, grounding points, or bearing fits.
- State if appearance approval samples are needed before full production release.
Useful finish inputs for an RFQ
Include the desired color or appearance family when relevant, the approved standard if one already exists, the visual acceptance boundary, any packaging concerns for cosmetic parts, and whether mixed-material assemblies need compatible finish behavior. If a standard is still under review, say so directly and let the quote identify open items.
FAQ
Surface finish selection for machined parts
Should cosmetic and functional finish requirements be listed separately?
Yes. Cosmetic acceptance and functional performance can affect different surfaces and different process controls, so combining them into one vague note creates avoidable risk.
Do finish requirements need masking notes in the RFQ stage?
They should be included whenever uncoated or protected zones are important to assembly, conductivity, sealing, bonding, or fit.
When should dimensional checks mention the finished condition?
Mention it whenever a coating, conversion, blasting step, or polishing sequence could influence the controlled feature or the inspection method.
Technical hub
Review finish intent before quoting
A clear RFQ can separate machined texture, secondary finish scope, masking needs, and inspection timing before production planning starts.
Upload finish requirements