{"id":6312,"date":"2026-05-21T03:32:25","date_gmt":"2026-05-21T03:32:25","guid":{"rendered":"https:\/\/nylonplastic.com\/surface-finish-standards-machined-components\/"},"modified":"2026-05-21T06:38:59","modified_gmt":"2026-05-21T06:38:59","slug":"surface-finish-standards-machined-components","status":"publish","type":"post","link":"https:\/\/nylonplastic.com\/ko\/surface-finish-standards-machined-components\/","title":{"rendered":"Surface Finish Standards for Machined Components: Complete Guide"},"content":{"rendered":"
\"Surface
Surface roughness measurement quantifies the microscopic peaks and valleys that determine fit, friction, and appearance<\/figcaption><\/figure>\n

Surface finish \u2014 the texture, roughness, and waviness of a machined surface \u2014 directly impacts component performance across multiple dimensions: wear resistance, friction characteristics, fatigue life, corrosion resistance, sealing effectiveness, and aesthetic quality. Specifying the correct surface finish standard is as critical as specifying dimensional tolerances.<\/p>\n

Understanding Surface Finish Parameters<\/h2>\n

Ra (Average Roughness)<\/h3>\n

Ra is the arithmetic average deviation of the surface profile from a mean line. It is the most widely used surface roughness parameter worldwide \u2014 though it has significant limitations. Ra does not distinguish between a surface with occasional deep scratches and one with uniform fine peaks and valleys; mathematically, both can produce the same average. Despite this, Ra remains the default surface finish specification for most engineering drawings.<\/p>\n

Rz (Mean Peak-to-Valley Roughness)<\/h3>\n

Rz averages the height difference between the five highest peaks and five lowest valleys within a sampling length. Unlike Ra, Rz is sensitive to occasional deep scratches or isolated surface defects \u2014 making it more useful for applications where peak-to-valley depth is critical (sealing surfaces, bearing journals).<\/p>\n

Rt (Maximum Roughness Depth)<\/h3>\n

Rt measures the absolute maximum peak-to-valley height within the evaluation length. This is the most conservative (highest reported value) surface roughness metric and is used for critical sealing and contact surfaces.<\/p>\n

\"Surface
Surface finish comparator plates provide visual and tactile references for common machining finishes<\/figcaption><\/figure>\n

Surface Finish Achievable by Process<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Manufacturing Process<\/th>\nTypical Ra (\u00b5in \/ \u00b5m)<\/th>\n\ucc38\uace0<\/th>\n<\/tr>\n<\/thead>\n
Saw Cut<\/td>\n250-500 \/ 6.3-12.5<\/td>\nRough, visible saw marks<\/td>\n<\/tr>\n
CNC Milling (roughing)<\/td>\n125-250 \/ 3.2-6.3<\/td>\nVisible tool marks, sharp edges<\/td>\n<\/tr>\n
CNC Milling (finishing)<\/td>\n32-63 \/ 0.8-1.6<\/td>\nStandard machined finish<\/td>\n<\/tr>\n
CNC Turning (finishing)<\/td>\n16-63 \/ 0.4-1.6<\/td>\nSmooth cylindrical surfaces<\/td>\n<\/tr>\n
Grinding<\/td>\n4-32 \/ 0.1-0.8<\/td>\nHigh-precision bearing journals<\/td>\n<\/tr>\n
EDM (single pass)<\/td>\n32-63 \/ 0.8-1.6<\/td>\nMatte EDM surface, recast layer<\/td>\n<\/tr>\n
EDM (skim pass)<\/td>\n4-16 \/ 0.1-0.4<\/td>\nPolished EDM with fine recast<\/td>\n<\/tr>\n
Lapping<\/td>\n1-8 \/ 0.025-0.2<\/td>\nOptical flatness, seal surfaces<\/td>\n<\/tr>\n
\uc5f0\ub9c8<\/td>\n1-4 \/ 0.025-0.1<\/td>\nMirror finish, plastic molds<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Surface Finish for Engineering Plastics<\/h2>\n

Engineering plastics machined with proper parameters achieve excellent surface finishes without post-processing:<\/p>\n