DFM: DFM (design for manufacturing) is the practice of shaping a part so it can be made reliably and cheaply by the chosen process, and the checks that flag features that will cause trouble.
Most of a part’s cost is decided when it is designed. A wall a little too thin, a corner too sharp for a cutter, an undercut a mould cannot release, or a tolerance tighter than the part needs: each can add cost, cause a failed build, or make the part impossible to produce.
DFM works on two levels. As a design practice, it means knowing the limits of a process before you draw. As a check, it means looking at a finished file for features that break those limits and telling the designer before the job starts.
Each process has its own rules. For 3D printing the usual checks are minimum wall thickness, small holes, trapped volumes of powder or resin, and overhangs. For CNC machining they are internal corner radii, deep pockets and tool access. For moulding they include draft angle and undercuts.
Example: a resin part has a 0.3 mm wall on a process where the shop’s minimum is 0.6 mm. A DFM check flags the wall before printing, the buyer thickens it, and the shop avoids a broken part and a free reprint.
DFM is often confused with DFA (design for assembly), which looks at how parts go together rather than how each is made. See DFM checks in Quotometry, which are shown to the buyer, or read design for 3D printing.
Go deeper: Design for 3D printing: walls, overhangs, holes, clearances and orientation