Browse PTI technical publications

The classical cyclone cut size model assumes discrete, non-agglomerating particles. Cohesive or moisture-sensitive fines can travel through a cyclone as agglomerates instead, which changes what a PSD result actually tells you about classifier performance.

Wood powder can bridge because fibrous particles mechanically interlock, because moisture increases [...]

Bulk-blended fertilizer fails in three recurring ways: segregation between straight materials of different size and density, hygroscopic caking in urea and ammonium nitrate under humidity cycling, and dust release during bagging. Each failure mode maps to a specific diagnostic test rather than a single generic powder check.

Vacuum conveying contains by default: any breach draws air inward rather than pushing powder out. That containment advantage comes with a fixed pressure budget, and filter design competes directly with conveying velocity for every millibar of available driving force.

Laser diffraction calculates particle size from measured scattering using an optical model [...]

Milling can reduce powder-bed permeability even when the material meets its [...]

Fumed (colloidal) silica improves powder flow by separating host particles and reducing [...]

Drying does not always improve powder flow. Dissolved material can form solid [...]

Hausner ratio, shear cell, and dynamic flow energy results on the same PBF powder lot rarely agree exactly. That disagreement is a decision input, not proof that a method or lab got it wrong.

DEM input parameters are fitted to match a bulk observable, not derived from first principles. A parameter set calibrated against an angle of repose test constrains one point in a multi-dimensional parameter space. When the hopper geometry changes, the stress state changes, and unconstrained parameters become the dominant source of prediction error.

CFD-DEM simulations show triboelectrically charged particles can reverse direction in low-drag duct corner zones during pneumatic conveying, with the delay between feed pulses driving the effect more than pulse length.

LED-based particle image velocimetry (PIV) images the velocity field inside a moving powder bed during blending, adding spatial resolution that static angle of repose, Hausner ratio, and shear cell tests cannot provide. Here is what that resolution can and cannot support for a process decision.

Jet milling micronization reduces particle size through particle-particle impact controlled by classifier wheel speed and feed rate. Pushing the cut point lower can raise amorphous surface content and hygroscopicity in ways a passing PSD result will not reveal. This guide covers the mechanism and the tests that actually diagnose a changed lot.

Jenike shear cells and ring shear testers measure the same yield locus through different mechanics. Here is how their sample, stress range, and time differences map onto the mass-flow versus funnel-flow hopper design decision, plus a checklist for choosing between them.

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.

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.