Custom parts
A dimensional tolerance does not define surface roughness, and a material selection does not include a coating.
Machined surfaces show toolpaths
Milling and turning leave different surface patterns. Feed direction, tool geometry, material, and setup influence the result. A smooth-looking surface is not a measurement of roughness or flatness. Functional contact surfaces need a deliberate specification when texture affects performance.
Use finish requirements selectively
Sealing faces, sliding surfaces, and appearance-critical areas may have different needs from hidden surfaces. Apply a roughness requirement to the relevant feature rather than every surface without purpose. Numeric finish values need units and a defined interpretation.
Coatings change the part
Anodizing, plating, painting, and other treatments can change dimensions, appearance, and corrosion behavior. Threaded and fitted features may need allowances or masking. These processes are scope items and are not implied by a base machining quote or by this educational guide.
Define the deliverable
Distinguish a standard machined surface from a cosmetic requirement, a deburred edge, and a special coating. If a drawing requires a finish or secondary process outside the online controls, use custom RFQ so the accepted quote defines what is included. This page is not a list of in-house finishing equipment.