FDA's proposed hub-and-spoke registration rule treats geographically separate manufacturing units as one establishment. The registration paperwork is new; proving that blend uniformity, granulation endpoints, and moisture behavior actually match between sites is the older, harder problem.
Powder spreading in powder bed fusion is a recoater-powder interaction shaped by cohesion, particle size distribution, and particle shape. This article maps streaking, short-feeding, and layer non-uniformity back to their underlying mechanisms and separates powder-driven causes from blade wear and spreading speed.
Dynamic and aerated powder testing measures basic flow energy and specific energy to fill the gap between shear cell consolidation data and Hausner ratio screening, particularly for fluidized processing and rapid-refill feeding.
As aerospace metal additive manufacturing capacity expands, more reused powder is going back into qualified builds. The virgin-to-reused blend ratio decision depends on PSD shift, satellite formation, and morphology drift, and cannot be settled by a single powder check disconnected from the part's stress state.
Two lots that pass the same incoming flowability spec can still granulate differently after roller compaction. The reason usually traces to ribbon density, which responds to roll force, gap width, and feed screw speed as an interacting set, not to roll pressure in isolation.
Talc's expected EU restriction is forcing cosmetic formulators toward mica, kaolin, silica, and starch. None of them reproduce talc's platelet slip, oil absorption, and low dustiness at the same time, and each substitution changes flow and compaction behavior in pressed powder products differently.
Geldart classification, minimum fluidization velocity, bubble dynamics, droplet-to-particle size ratio, and permeability all determine whether a fluidized bed process delivers controlled granule growth, uniform coating, or consistent drying at production scale.
Both the Hausner Ratio and Carr Index reduce bulk and tapped density to a single number. The mechanism behind that number, whether aeration, particle shape, or surface cohesion, determines whether it supports a process decision or actively misleads one.
The same screw feeder at the same speed can deliver consistently on one powder and drift by several percent on another. The difference lies in compressibility, wall friction, and cohesion, and in how bulk density shifts as the hopper empties.
Temperature shifts surface energy, contact compliance, and residual moisture state in ways that can reverse a powder's ambient flow behavior. This Insight explains the dominant mechanisms across three temperature ranges and what elevated-temperature testing reveals for SLS powder beds, spray dryer outlets, and heated conveying systems.
