CNC Surface Roughness & Finish: Ra Levels Explained (3.2 to 0.4 µm)
Learn what Ra and Rz mean, common CNC roughness levels (3.2 to 0.4 µm), and how they affect fit, wear, looks and cost.
Surface roughness is not just about looks. It can change friction, sealing, coating grip, wear, and even cost. ⚙️📏 This guide breaks down what Ra means, the most common CNC roughness levels (3.2, 1.6, 0.8, 0.4 µm), plus how finishes are achieved and measured, so you can spec the right finish for your next part. ✨🔩













