Change your testing process.
If you're using Carr's Index, angle of repose, or Hausner ratio, you already know their limitations. These tests assign broad categories to powders under specific circumstances—where the powders are freshly prepared, at rest, under gravity, in ambient humidity. These tests also do not predict powder behavior at production speed, after a period of storage, or when under compression.
That gap between what traditional tests can measure and what you actually need to know? That's the gap that the Powder Flow Analyzer closes.
- Improve the quality and consistency of your products
- Save costs by improving storage, handling, packing, and transportation
- Avoid downtime due to issues such as caking
Zero in on your issue - and solve it.
The Texture Analyzer can help you determine how powders deform, resist, and fail. Measure compaction strength, cake breakability, and penetration resistance. This is ideal for testing storage stability, tabletability, and structural integrity.
The Powder Flow Analyzer (PFA), placed directly on the Texture Analyzer, allows you to see how powders behave in motion. These tests can capture speed sensitivity, aeration effects, and flow instabilities.
Any industry that works with powders, at any stage of production, can use the Powder Flow Analyzer. Whether it's food, pharmaceuticals, agriculture, cosmetics and personal care products, and even batteries and advanced materials, the Powder Flow Analyzer can improve production and reduce manufacturing costs.
Use the diagnostic guide below to find your solution:
Problem
Powder Flow Analyzer tests
Texture Analyzer tests
Arching / Bridging
Flow stopping suddenly and a stable 'roof' forms; may restart after tapping or vibration.
Cohesion (1 speed): Bridging Factor can indicate any arch-forming tendencies; Cohesion Index shows inter-particle bonding strength.
Cohesion (4 speeds): To determine if cohesive bonding is dependent on speed.
Powder Consolidation and Caking: Use if arching is worse after storage or rest.
Unconfined Yield Stress Rig can measure the stress at which a formed structure will collapse.
Cake Strength/Break Test will quantify the force required to fracture a cohesive structure
Ratholing
The central channel flows freely, but powder closer to the walls stays stuck; this can cause a sudden collapse and surge.
Cohesion (1 speed): High Bridging Factor and consolidation often aligns with ratholing risk.
Compressibility: High compressibility supports may consolidate.
Powder Consolidation and Caking: Measures the level of how much the powder sets up during rest
Unconfined Yield Stress Rig: Measures the unconfined strength of the wall mass.
Powder Vertical Shear Rig: Determines shear strength, which can indicate if wall mass will remain stable or collapse.
Flooding / Flushing
Uncontrolled surges or dust clouds where powder doesn't meter or dose reliably.
Cohesion (1 speed): Will charaterize the low resistance and weak internal structure often typical of powders prone to flooding.
Powder Flow Speed Dependence (PFSD): Identifies speed-dependent behavior, which can reveal aeration effects.
Powder Penetration / Hardness: Low penetration resistance indicates a weak internal structure.
Uniaxial Powder Compression: Low yield point and work of compression revals poor structural resistance.
Won't start flowing
Powder doesn't start flowing when the gate first opens, needs agitation to restart.
Powder Consolidation and Caking: Quantifies energy required to re-initiate flow.
Caking: Trending cake strength indicates an increase in restart failure risk.
Cohesion (4 speeds): Indicates start/stop sensitivity.
Compressibility: High relaxation rate indicates powder consolidates and forms a stable structure during rest.
Powder Caking and Consolidation Rig: Determines the work and force needed to restart flow by breaking a consolidated bed.
Unconfined Yield Stress Rig: Measures the strength of the consolidated structure resisting flow initiation.
Erratic discharge / Surging
Output rate varies, causing intermittent pulses or avalanches.
Cohesion (1 speed): Bridging Factor detects instability and collapse behavior.
Powder Flow Speed Dependence (PFSD): Flow Stability records progressive changes and irregularity in discharge.
Powder Vertical Shear Rig Characterizes shear behavior that contributes to sporadic arch collapse events.
Powder Shear / Failure Energy: indicates when and how abruptly a powder structure releases.
Fill weight varies with line speed
Fill weight changes as dosing or conveying speed changes; higher speed starves or overfeeds.
Powder Flow Speed Dependence (PFSD): The Speed Sensitivity Ratio clearly indicates any fill rate changes with speed variations.
Cohesion (4 speeds): Separates low-speed and high-speed behaviors for scale-up insight.
Uniaxial Powder Compression: Measures compressive response under an increasing load—applicable to volumetric filling consistency.
Powder Penetration / Hardness: Surface hardness variation reveals inconsistent powder state entering the fill cycle.
Dosing drifts during a run
Feed rate changes over time despite constant settings.
Powder Flow Speed Dependence (PFSD): Flow Stability shows whether drift is progressive or will stabilize over time.
Cohesion (4 speeds): Can separate speed-driven drift from structure-driven drift.
Granule Compaction Rig: Determines if granule breakdown is driving change in feed rate.
Powder Shear / Failure: Checks if inter-particle strength changes as powder is worked.
Caking / Hard lumps
Hard lumps in product after storage or transport, requiring hammering or sieving before use; poor restart from silos.
Caking: Measures cake formation and cake strength after dynamic compaction cycling.
Powder Consolidation and Caking: Realistic "after load + time" cake strength under pre-determined conditions.
Compressibility: Identifies whether the powder densifies under stress.
Cake Strength / Break Test: Quantifies peak force and work to fracture, which is directly related to discharge and reprocessing specifications.
Powder Vertical Shear Rig: Measures how easily a formed cake will shear and break during handling.
Powder Penetration / Hardness: Surface hardness of the cake indicates level of bonding post-storage.
Density changes after handling
Powder is noticeably denser after vibration or transport; bulk behavior changes with head load.
Compressibility: Profile shows how much the powder densifies under increasing load and how much recovers.
Caking: Column height ratio is a sign of strong consolidation.
Uniaxial Powder Compression: Measures stiffness, yield behavior, and stress–strain response under static load.
Powder Penetration / Hardness: Tracks changes in hardness as a function of consolidation state.
Sticking / Build-up on equipment
Powder adheres to walls, feeders, or hoppers, leaving a residue, which in turn requires increased cleaning.
Cohesion (1 speed): High Cohesion Index demonstrates strong inter-particle and particle-surface bonding.
Cohesion (4 speeds): Indicates whether adhesion is speed-dependent, relevant to feeder and conveyor design.
Powder Vertical Shear Rig: Quantifies wall friction and adhesive force between equipment surface and powder.
Powder Shear / Failure: Measures inter-particle cohesive strength under static conditions.
Segregation / Blend non-uniformity
Composition changes over time or during a run; inconsistent potency, flavor, or particle size.
Powder Flow Speed Dependence (PFSD): Detects speed sensitivity and instability, two causes of segregation in handling.
Cohesion (1 speed): Notes cohesive behavior and ratholing tendencies that can cause collapse-driven redistribution.
Granule Compaction Rig: Assesses mechanical strength differences between blend components.
Powder Shear / Failure: Weaker components generate finer particles that segregate preferentially.
Attrition / Increasing fines
Product becomes dustier with handling; filters may load faster; flow behavior changes over time.
Powder Flow Speed Dependence (PFSD): Flow Stability determines if resistance changes progressively, which can indicate a breakdown or hardening during the test.
Cohesion (1 speed): Determines whether increasing fines are raising cohesive resistance over time.
Granule Compaction Rig: Measures hardness and fracture resistance of individual granules.
Powder Penetration / Hardness: Measures surface strength and susceptibility to mechanical damage.
The Test, Step by Step:
A precision helical blade moves through powder under controlled conditions. The instrument measures axial force, time, and distance, and our Exponent Connect software uses this data to quantify the powder's behavior.
- Select your test or configure your own - the instrument is fully programmable, allowing you to design a test that can precisely mimic your production environment.
- Load the sample and run the conditioning program, thus eliminating variability.
- Begin the test. The blade will behave precisely as programmed, and a transducer will measure axial force, time, and distance. Results are analyzed in real time through the Exponent Connect software, and then key parameters are calculated using pre-configured macros.
By repeating the test on multiple batches of powder, you can assess the effects of external conditions such as humidity and moisture content, determine differences in suppliers, or compare formulations quickly and efficiently.
Your container makes a difference.
Powder flow behavior is determined by how particles interact with each other - but also how they interact with their surroundings. For this reason, the PFA offers two vessel materials, glass and split aluminium. Each of these containers causes a difference in powder flow, giving you even more diagnostic information.
Glass vessel
Best for
- Rapid screening and comparison
- Visual observation during tests
- Assessing cohesive or electrostatic-sensitive behavior
Key characteristics
- Smooth nonreactive surface
- Electrically insulating
- Clear visibility of powder behavior
Aluminium split vessel
Best for
- Industrially representative testing
- Bulk density measurement
- Evaluating friction
Key characteristics
- Conductive surface
- Enables bulk density measurement
- Representative of commonly-used equipment
You've got questions? We can help you find the answers.
Test how powder deforms, resists, or fails under load, or how it behaves when in motion. The most common tests are listed below:
Test type
Key parameters and outputs
What can it help with?
Cohesion (1 speed)
Cohesion Index (work done during lifting phase at a defined speed)
Bridging Factor
Arching, bridging
Poor hopper or bin discharge
Powder sticking to equipment
flow variability over batches
Cohesion at 4 speeds
Cohesion Index at four speeds
Compaction coefficients
Flow Stability
Sensitivity to speed changes
Flow unstable during dosing or mixing
Assessing risks in scaling up
Powder flow speed dependence (PFSD)
Compaction coefficients on various speeds
Cohesion coefficient at a reference speed
Speed Sensitivity Ratio
Flow Stability
Feeding and conveying issues at higher speeds
Speed-dependent attrition, segregation, or aeration
Flow instability and dosing drift
Caking
Column height ratios
Cake height ratios
Cake Strength
Mean Cake Strength
Caking during transport or storage
Cake strength when consolidated
Difficulty emptying bins, packages, or silos
Powder Consolidation and Caking
Work to break consolidated cake after defined load and time
Failure in flow after storage
Consolidation under weight of product
Incomplete or delayed discharge
Restart problems after rest
Compressibility
% Compressibility
% Relaxation
Stiffness
% Elastic Recovery
Behavior while filling capsules and tablets
Settling and packing during storage
Blend and formulation optimization
Density changes after handling
Bulk density
Conditioned bulk density (g/ml)
% Elastic Recovery
Variations in fill weight
Optimizing pack size
Supplier and material grade comparison
Custom Controlled Flow tests
User-defined force, distance, work, and stability metrics
Special processes
Novel powders
R&D screening
Bespoke method development
Questions? Looking for more information?
