About 3Diligent and Rapid Manufacturing


Post-Processing Techniques and Smoothness Factors

3Diligent supports a myriad of different finishing techniques.  Finishing techniques can serve to make a surface smoother or rougher, or to give it unique surface properties for a given application.

Defining Finish Level

Much of 3Diligent's supply base - especially those working with metals - will utilize Ra as a term to demonstrate the relative smoothness of a surface.  This allows manufacturers to achieve a universal degree of finish across the many processes and materials available through the platform. For a definition of Ra, please review the information at these links:



When submitting an RFQ, you are welcome to reference a specific Ra level you would like to achieve on your parts.  It is worth noting that "as printed" finish can vary from ~Ra 32 on stereolithography (SLA) or digital light processing (DLP) prints to as high as Ra 600-800 on as-printed electron beam melting (EBM) metal prints. 

Finish Examples

For reference, below are pictures of parts next to American coinage and their approximate Ra levels:


Ra 800 (EBM as-printed displayed)


Ra 400 (DMLS as-printed displayed)


Ra 250 (top), Ra 125 (bottom) (DMLS with some finishing displayed)


Ra 50 (CNC displayed)


Ra 32 (SLA displayed)

Ra 16 or less – Differences in finish for parts of Ra 16 and below are difficult to convey via photo, although the reference coins provided in these photographs demonstrate a degree of mirror finish.