The flow of powder into simple and stepped dies

Wu, Chuan‐Yu; Dihoru, Luiza; Cocks, A.C.F.

doi:10.1016/s0032-5910(03)00130-x

Cited by 117 publications

(127 citation statements)

References 18 publications

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“…Sinka et al applied the same system in an attempt to characterize the flow behavior of pharmaceutical powders in dies and made similar observations as Wu et al. 13,18 Mendez et al used a fixed feed frame and a moving die disc system to examine the effect of blend composition, shoe properties and die parameters on flow properties, uniformity of die filling and applied shear of pharmaceutical blends. 10 This study showed that the amount of powder entering the dies depended on blend flow properties, the speed of the paddles in the feed frame and die disc speed.…”

Section: Introductionmentioning

confidence: 91%

“…17 Wu et al used transparent stationary dies and moving feeding shoes of simple and complex geometries to study the powder flow of different metallurgical powder components in air and vacuum. 18 His experiments showed that powder characteristics, shoe speed, die geometry and airflow play an important role in the die filling process. Sinka et al applied the same system in an attempt to characterize the flow behavior of pharmaceutical powders in dies and made similar observations as Wu et al.…”

Section: Introductionmentioning

confidence: 99%

“…Wu et al, for instance, ignored the effects of airflow, air pressure and cohesive forces in his DEM simulations, whilst other researchers draw their conclusions about die filling on a high speed rotary tablet press from passive die filling experiments (moving fill shoe and steady die). 9,13,18 Hence no set-up covered the complete range of factors involved in this complex process. Furthermore, the existing conventional techniques for measuring flowability do not directly provide relevant and applicable information for the selection of press parameters during die filling on a rotary tablet press.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reduction of tablet weight variability by optimizing paddle speed in the forced feeder of a high-speed rotary tablet press

Peeters

Beer

Vervaet

et al. 2014

Drug Development and Industrial Pharmacy

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Context: Tableting is a complex process due to the large number of process parameters that can be varied. Knowledge and understanding of the influence of these parameters on the final product quality is of great importance for the industry, allowing economic efficiency and parametric release.Objective: The aim of this study was to investigate the influence of paddle speeds and fill depth at different tableting speeds on the weight and weight variability of tablets. Materials and methods:Two excipients possessing different flow behavior, microcrystalline cellulose (MCC) and dibasic calcium phosphate dihydrate (DCP), were selected as model powders. Tablets were manufactured via a high speed rotary tablet press using design of experiments (DoE). During each experiment also the volume of powder in the forced feeder was measured.Results and discussion: Analysis of the DoE revealed that paddle speeds are of minor importance for tablet weight but significantly affect volume of powder inside the feeder in case of powders with excellent flowability (DCP). The opposite effect of paddle speed was observed for fairly flowing powders (MCC). Tableting speed played a role in weight and weight variability, whereas changing fill depth exclusively influenced tablet weight. Conclusion:The DoE approach allowed predicting the optimum combination of process parameters leading to minimum tablet weight variability. Monte Carlo simulations allowed assessing the probability to exceed the acceptable response limits if factor settings were varied around their optimum. This multi-dimensional combination and interaction of input variables leading to response criteria with acceptable probability reflected the design space.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reduction of tablet weight variability by optimizing paddle speed in the forced feeder of a high-speed rotary tablet press

Peeters

Beer

Vervaet

et al. 2014

Drug Development and Industrial Pharmacy

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show abstract

“…Particle segregation of dry powder particles has been studied by die filling, shear blender, rotating blender, vibrated shaker, Hele Shaw cells and fluidized beds using measurement techniques such as optical techniques, particle image velocimetry, radioactive particle tracking and infrared or near-infrared spectroscopy [5][6][7][8][9][10][11][12][13][14]. It is well accepted that size and density are the two main factors responsible for particle segregation.…”

Section: Introductionmentioning

confidence: 99%

Segregation measurement of powder injection molding feedstock using thermogravimetric analysis, pycnometer density and differential scanning calorimetry techniques

Demers

Turenne

Scalzo³

2015

Advanced Powder Technology

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“…During die fill the air pressure is increased as the powder is introduced into the die. The interplay between powder and air during die fill has been studied using model shoe-die systems [26,27]. Models for mass flow rate have been developed [28] prompting further research on air pressure effects in die fill [29,30], and on understanding suction fill mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Vacuum assisted flow initiation in arching powders

2016

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Graphical abstract Highlights• Vacuum applied at the exit of an arching hopper assists flow initiation.• A small reduction of pressure changes the critical orifice diameter significantly.• A dimensional model was developed to predict the pressure required to initiate flow. 2 AbstractThe discharge of powders from hoppers usually takes place in open atmosphere. However, in powder pressing industries (e.g. manufacturing of pharmaceutical tablets, detergents, ceramics, powder metallurgy etc.) there are handling operations where powders are filled into closed cavities such as dies. During this process the air pressure is increased as powder is delivered into the die. At the same time typical tablet production equipment creates a suction effect. A critical orifice measurement apparatus was developed to study powder flow initiation from an arching state into an enclosure where the air pressure is reduced. It was shown that a very small reduction of pressure changed the critical orifice diameter significantly. Dimensional analysis was carried out to relate powder properties (particle size and density) and processing parameters (geometry of the system and differential pressure necessary to break the arch). A relationship was developed to calculate the pressure difference necessary to initiate powder flow. The relationship has two empirical parameters which are calibrated by performing simple experiments using the testing rig developed.

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The flow of powder into simple and stepped dies

Cited by 117 publications

References 18 publications

Reduction of tablet weight variability by optimizing paddle speed in the forced feeder of a high-speed rotary tablet press

Reduction of tablet weight variability by optimizing paddle speed in the forced feeder of a high-speed rotary tablet press

Segregation measurement of powder injection molding feedstock using thermogravimetric analysis, pycnometer density and differential scanning calorimetry techniques

Vacuum assisted flow initiation in arching powders

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