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Powder Characterization /Flow/Shear Strength etc

There are many different approaches to characterization of powder behavior. At PMC4U we subscribe to the view that you need to characterize a powder as the bulk assembly of particles, moisture and air that make up its consistency and the other environmental factors that influence it e.g. stress, aeration, vibration. Too often our focus remains solely on the particles that make up the powder we see before us. Only by measuring a powder and its properties as a whole can you make accurate measurements and scientifically valid predictions to its behavioral properties. 



Powder Storage and transportation

Whether you store or transport your powders in small containers, bags, drums or large silos we all know that many factors affect your powder during this period. Time, humidity, consolidation or vibration can all affect your powders behavioral characteristics once used in production. It is vital to recognize the importance of these influences as to avoid faulty batches or powder/,material waste. This area is often overlooked yet can lead to huge cost reductions on an annual basis.









Silo Storage

Storage Silos are prone to many problems: bridging, arching, flow problems, storage problems, humidity issues or other weather dependent problems, dusting, consolidation with time and many more issues. At PMC4U we have access to the analytical tools that can help you determine the origins of these problems, we also have warm contacts with equipment suppliers that can help you alter your setup or add additional equipment to ensure resolution of your problems.




Big Bag storage & (flow) problems

Product tests on site secure measured values of a.o. powder flow, wall friction and shear strength that identify the flow potential of the material in question. 

These provided a basis for equipment design or adjustment; a.o. for screw sizing and inlet geometry to prevent arching, bridging or other flow problems. 

PMC4U has experience with a large variety of emptying and loading methods, dusting problems, vacuuming and storage issues like consolidation.

Testing can also be arranged in our partner laboratories at favorable rates should your laboratory lack the equipment or if you wish to oursource.

Powders are bulk materials, made from:

• Solids (the particles)

• Liquid (water on the surface of the particle, in the particle or in the air between particles)

• Gas (normally air, between particles or fibrous materials, can also be absorbed by particle however!)

How these three phases interact determines their behaviour thus making powders extremely complex materials

• Powders (particles, gases & liquids) and Particles(solid particles) are two fully separate  entities, one being a bulk assembly of 3 phases the latter being a collection of solids

• Much scientific debate has been ongoing about how to best characterize materials.

• Particle characterization allows for the determination of a large amount of specific detailed information about the particles and their properties e.g. Specific gas absorption of particles, surface texture etc

• Powder characterization allows for the behavioural analysis of the bulk assembly E.g. Flow properties, compressibility etc

• Obviously these sciences overlap since particle characteristics do contribute to powder behaviour. But particle characterization alone is not enough nor is it a good scientific approach to predicting bulk assembly/ powder behaviour


Particle characterization


  • Particle Size & Distribution
  • Shape
  • Surface Texture
  • Surface Area
  • Density
  • Cohesion
  • Adhesion
  • Elasticity
  • Plasticity
  • Porosity
  • Potential for electrostatic charge
  • Hygroscopicity
  • Hardness / Friability
  • Amorphous content

All of these detailed particle characteristics contribute to powder behaviour.


Powder Characterization 


Powder Behaviour = fn (particle characteristics) + fn (environmental factors like humidity and aeration of the powder) + fn (material of production equipment used) + fn (packing state of powder, consolidated, loose, fluid like) + fn (MANY MORE FACTORS)....

This is why at PMC4U we look at the bulk assembly when predicting powder behaviour in specific environments or circumstances.


Important things to recognize:

  • Particle properties do not always influence powder behaviour or only part influence behaviour; a powder is a bulk assembly that as a whole also is prone to different stress regimes that influence the packing state.
  • Your material is exposed to many different stress regimes during your processes
  • Gaining predictive insights into behaviour of your material during specific processes allows for more lean management of the whole process and thus cost reductions overall
  • If your material does not behave as required under specific conditions this may influence your final product


We will soon be adding additional information to this section