DFM Drawing Review Checklist

Material & specs

Material is called out by canonical spec (AMS, ASTM, MIL, etc.) — not just chemistry name.
Material condition / temper / heat treat is specified (e.g., T6, H900, Q&T 28-32 HRC).
Material isn't over-specified — chosen for actual property requirement, not legacy default.
If aerospace/medical — CMTR or certified traceability is required and noted.

General tolerance class invoked (ISO 2768-m or similar) — not left to interpretation.
Tight tolerances (≤ ±0.001″) are limited to features that genuinely require them.
Tight-toleranced features are on the same setup / datum scheme — not spread across multiple ops.
GD&T is used where it adds clarity (position, profile, flatness) instead of stacked ± tolerances.
Tolerance stack-ups have been checked for worst-case fit.

Internal corners have radii ≥ 0.060″ (or larger for deep pockets) — not square.
Pocket floors allow a bullnose tool radius (R 0.030″+ if possible).
Pocket depths are within ~4× usable tool diameter.
Wall thicknesses respect the material minimum (Al 0.8 mm, SS 1.0 mm, Ti 1.5 mm, etc.).
Undercuts and back-features are flagged or eliminated where possible.

Hole sizes are standard (drill, ream) where tolerance allows.
Hole depth-to-diameter ratios are ≤ 5:1 unless deep-hole drilling is acceptable.
Cross-drilled holes have a milled flat at the entry surface.
Tap depth ≈ 1.5×D in steel/stainless/titanium, 2×D in aluminum or magnesium, 2.5×D+ in plastics (or use a threaded insert) — not full hole depth.
Drill depth = tap depth + 1× thread diameter for chip clearance.
Threads are UNC, UNF, or metric coarse — not custom pitches without reason.

General surface finish defaults to as-machined or 125 µin Ra — not 32 µin everywhere.
Tighter finishes (≤ 32 µin) are limited to functional faces (sealing, mating, optical).
Cosmetic surfaces specify lay direction explicitly (e.g., parallel to long axis).
Coating / plating callouts include dimension build-up allowance.

Primary datum is on a feature that can actually be clamped or located against.
Cosmetically asymmetric features (where symmetry would also work) are eliminated.
Number of machining setups is minimized — design enables single or two-side ops where possible.
If aerospace — FAI per AS9102 is required and accommodated in the schedule.

ITAR / EAR controlled tech data flagged on drawing — emailed to sales@digitalmachine.com, never entered in a public web form.
If DoD — DFARS specialty metals, DPAS rating, and Buy American clauses checked.
If EU/RoHS — restricted substances (Pb, Cd, Cr+6) avoided in materials and finishes.
Inspection plan documented (FAI, in-process, final) — first-article expectations clear.