Cohesiveness is a key factor influencing the performance of materials in different applications. In fields such as pharmaceuticals, food processing, and manufacturing, knowing the cohesiveness of powders and granules is essential for predicting how materials will behave under different conditions.
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Cohesiveness refers to the degree of attraction between similar particles within a powder and can be measured by the angle of repose, angle of fall and angle of difference. Besides this, it can also be assessed through shear cell testing, where the powder is subjected to controlled shear forces.
The angle of repose refers to the angle between the sloping side of a powder cone and the horizontal plane after the powder particles freely fall onto a horizontal plane under specific conditions. The angle of repose is a significant indicator of powder flowability. The smaller the angle of repose is, the better the flowability will be. It is generally assumed that the angle of friction and the angle of repose are approximately equal. For some materials, such as sorghum, the magnitudes of the two angles can be different.
The angle of fall is the decreased angle obtained after the angle of repose has been measured, and the powder pile is subjected to regular mechanical vibrations. During the vibration, the particles slide down the powder pile along the sloping surface, resulting in a decreased tilt angle which is called the angle of fall.
The angle of difference is calculated by subtracting the angle of fall from the angle of repose. The angle of difference is one of several parameters that can be used to evaluate powder flowability. The larger the angle of difference is, the better the flowability will be.
Powder Flow Tester (PFT)
Brookfield
Discover the trusted Brookfield Powder Flow Tester, a cornerstone in the industry for evaluating flow function and wall friction of powders. This instrument plays a vital role in quality control and process optimization, offering valuable data on the relationship between consolidation stress and powder flow.
The PFT delivers quick and easy analysis of the powder flow behaviour.
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PowderPro X1
Bettersize
PowderPro X1 combines automated powder characterization with 18 critical parameters on one integrated platform. It evaluates angle of repose, bulk and tapped density, dispersibility and flow rate, aligned with 20+ international and industry standards for efficient R&D, quality control and compliance.
GTB
Erweka
The Erweka GTB (Granule and Powder Flow Tester) is a specialized instrument designed to evaluate the flow properties of granules and powders according to USP/EP-compliant methods. This versatile tester offers valuable insights into key parameters such as flowability (measurement by volume or weight) and the angle of repose.
