A printed part is not automatically equivalent to the same material made by another route.

Layerwise manufacturing can produce several process-specific features:

• directional bonding or microstructure, causing anisotropy;
• pores from incomplete fusion, trapped gas or deposition gaps;
• rough surfaces associated with layers, powder particles or deposited roads;
• residual stress and distortion from nonuniform thermal history;
• support-contact regions that differ from freely built surfaces.

Postprocessing is therefore often part of the manufacturing route rather than an optional cosmetic step. Examples include support removal, machining of datum surfaces and holes, heat treatment, stress relief, hot isostatic pressing for suitable metal parts, cleaning and polymer post-cure.

Suppose a printed hole must mate with a precision bearing. Printing may create the near-net geometry, while a later boring or reaming operation provides final diameter and surface capability. The process route is additive plus subtractive finishing.

Property qualification must also respect build direction. If coupons are tested only along one orientation, they may not characterize a component whose critical load acts across layers.

The correct mental model is therefore

build process -> defects + microstructure + residual stress
                         ↓
                   postprocessing
                         ↓
               final geometry/properties

AM performance belongs to the complete route, not just the machine's build step.