Comparative evaluation of Peschl and FT4 full-bed rotational shear cells for powder flow characterization

Abstract

The method of shear cell testing plays a pivotal role in assessing the flowability of powders, notably in the context of evaluating pharmaceutical formulations and processes. Despite numerous studies on shear cell methodology and its diverse applications, there remains a need to compare the performance of specific shear cell designs. This study addresses this gap by offering a comprehensive comparison of two full-bed rotational shear cells – the Peschl and FT4 cells.

Highlights

• Two full-bed rotational shear cells, Peschl and FT4, were comparatively evaluated.
• Resulting yield loci are consistent with accepted values for BCR 116 limestone.
• Peschl and FT4 shear cells give statistically different results.
• Variability due to operator was statistically insignificant for both shear cells.
• Critical arching diameter provides a more direct measurement at low normal stresses.

The evaluation focuses on assessing the precision and accuracy of each instrument, considering six materials: two reference materials with well-established behavior and four pharmaceutically relevant materials. Key parameters obtained from the measured yield loci were analyzed and compared, shedding light on the differences in performance between the two shear cells. Statistical analysis using regression methods revealed the significance of not only the test material but also the shear cell used for measurement, emphasizing the influential role of shear cell design.

Additionally, this work delves into the significance of powder bed density during shear cell measurements and its broader implications for comprehensive powder characterization, providing valuable insights for the field of material science and pharmaceutical formulation.

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Materials

The materials used in this study, along with relevant physical properties, are listed in Table 1. Several pharmaceutically relevant powders commonly used as excipients in solid oral dosage forms that span a range of flowability behavior (cohesive to free flowing) were selected. BCR 116 limestone as a reference cohesive material and MCC Celphere CP-507 as a reference free-flowing material were also included. A single lot of each material was used for all characterization presented herein.

Sara Koynov, Kristen Duda, Plinio A. De los Santos, David J. Goldfarb, Comparative evaluation of Peschl and FT4 full-bed rotational shear cells for powder flow characterization, Powder Technology, Volume 456, 2025, 120810, ISSN 0032-5910, https://doi.org/10.1016/j.powtec.2025.120810.

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