Headline changes
MMPDS-2024 introduces §9 'Additive manufacturing data submission requirements' as a dedicated chapter. Prior editions handled AM data as a sub-section of §8; promoting it to a top-level chapter signals that AM-specific qualification language is now mainstream rather than experimental.
- Minimum coupon count for A-basis raised from n = 60 to n = 75
- Mandatory disclosure of build orientation, support strategy, and HIP cycle
- Walker exponent fitting now permitted as the default mean-stress correction (was Goodman)
- Two new allowables families: L-PBF AlSi10Mg-T6 and L-PBF Inconel 625 (HIP + age)
Why the n = 75 floor matters
The k-factor for one-sided 95/99 normal-tolerance on n = 60 is 2.404; on n = 75 it drops to 2.336. That alone would lift A-basis values by ~2–3%. The real motivation is the heavy-tailed defect distribution: at n = 60 you have a meaningful probability of missing the lower-tail entirely. n = 75 reduces that risk to acceptable levels without doubling test cost.
What submission packages need to include now
Beyond the coupon set itself, MMPDS-2024 requires: machine OEM and serial, parameter set version, powder lot and PSD, atmosphere O₂/H₂O/N₂, layer thickness and hatch strategy, scan strategy variant, build plate temperature, and full thermal-history of each post-processing step. ForgeCast captures all of this in the wizard's qualification panel and emits a compliant submission summary as a side artefact.
Frequently asked questions
Does ForgeCast track MMPDS revision dates?
Yes. Each allowable in the database carries the MMPDS edition it was derived against, plus the date of the last in-house revalidation. The wizard surfaces both on every result card.
Sources
- MMPDS-2024 (Metallic Materials Properties Development and Standardization), Battelle Memorial Institute.
- FAA AC 33.15-3, Powder Bed Fusion Powder Specifications (2023).