News on how Freeze Granulation can improve our powder properties

Preparation of PIM or Extrusion Feedstock

Freeze Granulation of PIM or Extrusion Feedstock

Powder injection molding (PIM) and extrusion are powder shaping techniques that typically involve preparation of high viscous feedstock making it difficult to achieve full homogeneity. Especially if the powders are fine (submicron or nano) and/or if it is a composite material. By doing an initial preparation of a low viscous (based on water or organic) suspension the powders can be properly de-agglomerated, dispersed and homogenized. Other constituents aimed for the PIM or extrusion process can be added prior to freeze granulation. The result will be a homogenized, soft and dust free powder, easy to mix and disperse into a feedstock for PIM or extrusion at high powder concentration and homogeneity, promoting sintering and ultimate material performance.

Please contact us and we will further discuss the opportunities with Freeze Granulation on your powder system and read more on technology and we propose a Granulation Test of your powder system.

Preparation of PIM or Extrusion Feedstock

Frysgranulering för tillverkning av homogena granuler

PowderPro har i samarbete med Swerea IVF (då Svenska Keraminstitutet) under 1980-talet vidareutvecklat en alternativ granuleringsteknik – frysgranulering (Freeze Granulation) – vilken möjliggör konservering av homogeniteten från suspension till torrt granulat. Genom att spreja en pulversuspension ner i flytande kväve sker en momentan frysning av dropparna (granulerna). I den efterföljande frystorkningen sublimeras isen utan risk för segregeringseffekter som lätt sker vid konventionell torkning i luft. Resultatet blir sfäriska och friflytande granuler med optimal homogenitet lämpliga för t ex pressning av keramiska komponenter.

Frysgranulering: Homogena pulvergranuler med överlägsen prestanda

Freeze Granulation produce flowable and crushable (soft) granules

Freeze Granulation produce flowable and crushable (soft) granules suitable for die pressing applications. Spray drying yield flowable, but hard granules which are difficult to cruch during die pressing.

Freeze Granulation vs Spray Drying advantages — Freeze Granulation vs Spray Drying

Can you make spherical granules?

Yes, with Freeze Granulation it’s possible to make spherical, homogeneous and dust-free granules with optimal flowability which is critical for automatic uniaxial pressing of for ex ceramics and metal powders.

You can expect spherical and homogenous granules of powders in terms of distribution of particle size and other possible additives you want to use. The granules with a size distribution in the range of 50-300 microns will have weak inter particle bonding making them easy to break down in pressing or re-disperse into another formulation. Very much depend upon how you intend to process the powder and depending on that, adaptation can be made. If you tell us more we can further discuss the opportunities.

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Spherical granules made by Freeze Granulation

Homogeneity preservation from suspension to dry granule

If you are looking for optimal homogeneity in your granulated material, then you should evaluate our unique granulation technology – Freeze Granulation!

Today, Freeze Granulation is the only granulation technology that will preserve the homogeneity from suspension to dry granule, which is crucial for good results in most processes.

Spray cooling or rather called spray freezing is the first step in the freeze granulation process where a suspension is atomized, sprayed with a nozzle, into a chamber with liquid nitrogen. The small droplets are then rapidly frozen with a minimum of ice crystal growth. The frozen material (granules) are then transferred to a freeze dryer where the ice is removed by sublimation, i e never go through a liquid state that ensure homogeneity preservation.

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Superabrasive Grinding Tools

Superabrasive grinding tools by Freeze Granulation

Freeze Granulation is today being used for the production of high quality superabrasive grinding tools, where the superabrasive grains are homogeneously distributed in the grinding tool. This results in a grinding wheel with higher grinding capacity and longer grinding and cutting tool life.

Homogeneous granules of superabrasive grinding material.

Carbon nanotubes deagglomeration

Carbon Nanotubes deagglomeration by Freeze Granulation

By using Freeze Granulation it is possible to disperse and avoid agglomeration of Carbon nanotubes. Carbon nanotubes can be granulated and dried into a powder and then re-dispersed to nanopowders again avoiding agglomeration (aggregates) of nanoparticles, which is not possible with other granulation methods like spray drying.

Freeze granulation gives the possibility to granulate nanoparticles achieving granules with high degree of homogeneity which are easily re-dispersed (if applicable) in a liquid or dis-integrated at a pressing operation. This is owing to the week inter-particle bonding compare to what is obtained in conventional drying. Consequently, the nanosized material properties will be preserved, i.e. nano will still be nano. Freeze-drying also prevents oxidation of metals or non-oxide materials as conventional drying do not, especially critical for nanopowders.

Freeze Granulation of nanopowders

Carbon nanotubes (CNT)

Freeze Granulation of Carbon Nanotubes (CNT)

By using Freeze Granulation it is possible to disperse and avoid agglomeration of Carbon Nanotubes. Carbon nanotubes can be granulated and dried into a powder and then re-dispersed to nanopowders again avoiding agglomeration (aggregates) of nanoparticles, which is not possible with other granulation methods like spray drying.

Synthetic diamond powder granulation

Homogeneous diamond tools by Freeze Granulation

Synthetic diamond powder granulation is today being formed by Freeze Granulation for to make homogeneous granules for diamond tools with long tool-life and optimal performance. Please contact us for more information and a test-granulation of your system.

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Please contact us and we will further discuss the opportunities with Freeze Granulation on your diamond powder system and read more on technology and we propose a Granulation Test of your powder system.

POWTECH 2013 – Nürnberg

Second day @Powtech 2013 in Nürnberg, spring in the air! Good and interesting meetings on powder processing and how Freeze Granulation can improve the homogeneity of the granules, for example nanomaterial like CNT – Carbon Nano Tubes.

Please contact us for more information and a test-granulation of your powder system.