What kind of surface finish does CNC machining leave?

Once the machining process is complete, the CNC parts surface will have slight visible tool marks, called “as-machined” or “as-milled” surface finish. Machined surface roughness (Ra) is standardized at 1.6-3.2 μm, and surface finish requirements can be increased to 0.8-1.6 μm or higher at 0.2-0.8 μm, however, this will require more operating time and higher costs.