Surface Roughness Explained | Ra Roughness Chart

This resource will share ways to measure and compare surface roughness in CNC machined parts, extrusions, moulding, casting and 3D printing, as well as standard surface finishes to expect. If you are unsure of the standard surface finishes for precision machined parts, or how to measure surface roughness, read on. What is surface roughness in machining and manufacturing?Surface roughness is the measurement of the relative smoothness of a surface’s profile, calculated via the microscopic deviations in a surface's true form. The larger the deviation from its true form, the rougher the surface, whilst the smaller the deviation, the smoother the surface.{{cta-banner}} Surface roughness in CNC machined partsIn CNC machining, the surface roughness will influence how the manufactured part will interact with the surrounding environment. A typical CNC machining finish, ‘as machined’, is smooth to the touch (Ra3.2) but will contain visible machining lines from the cutting tool. This level of rou...