This study is part of an ongoing project to enable the full specification of the Design Space for roller compactor systems and shows how the processing parameters influence the behaviour of the product granulate from ...This study is part of an ongoing project to enable the full specification of the Design Space for roller compactor systems and shows how the processing parameters influence the behaviour of the product granulate from a placebo formulation. Granulate was produced using a proprietary roller compactor by varying the compaction pressure and gap width,and the dynamic, bulk and shear properties of the resultant granulates were measured.The results demonstrate several rheological properties of the granulate, which have been shown to be closely correlated with variance in die filling and tablet strength, and are predictably influenced by the processing parameters.展开更多
3D MicroPrint公司率先使用了增材制造(AM)来生产复杂、微米尺度的金属部件,公司正在使用英国富瑞曼科技公司的FT4粉体流变仪来识别超细粉能否有效加工,这家公司使用小于5pm的粉末来成型具有极高精度和分辨率的组件。FT4粉体流变仪能够...3D MicroPrint公司率先使用了增材制造(AM)来生产复杂、微米尺度的金属部件,公司正在使用英国富瑞曼科技公司的FT4粉体流变仪来识别超细粉能否有效加工,这家公司使用小于5pm的粉末来成型具有极高精度和分辨率的组件。FT4粉体流变仪能够区分出流动性优越的原材料,并成功应用于3DMicroPrint的微激光烧结(MLS),在医疗、半导体、航空航天、能源和化工等领域取得成功。展开更多
Powder flow behaviour is the result of countless combinations of interparticle forces of different natures: frictional,interlocking,cohesive and adhesive forces.We identify the rheological tests where one mechanism is...Powder flow behaviour is the result of countless combinations of interparticle forces of different natures: frictional,interlocking,cohesive and adhesive forces.We identify the rheological tests where one mechanism is most likely to dominate over the rest,and we propose the best descriptors of uniquely cohesive or frictional effects.We describe the procedure for a fluidisation test and the features of the results linked to powder cohesivity.We contrast these features against shear test results to determine powder frictional properties,explaining the conditions and limitations of the analysis.We use solid volume fraction and compressibility measurements to assess the extent to which the different mechanisms influence natural packing and forced flow in intermediate stress regimes.The proposed experimental protocol and framework of interpretation is applied to a wide range of powdered materials,representing typical industrial issues.The qualities of the characterisation are discussed and compared to those associated with traditional rheological testing methods.The framework successfully differentiates the effects of the various interparticle interaction mechanisms on powder flow,enabling a comprehensive prediction of powder behaviour in a variety of handling and processing settings.The metrics used are all normalised,allowing for a universal direct comparison of flowability across completely different materials.展开更多
The shape and size of particles are understood to affect the bulk behaviour of powders, though there are but few studies that present quantitative information on the relationship between particle shape and the flow pr...The shape and size of particles are understood to affect the bulk behaviour of powders, though there are but few studies that present quantitative information on the relationship between particle shape and the flow properties of powder. This is due in part to the lack of techniques for rapidly determining both particle shape and the range of flow characteristics that describe the response of powders to the stress and shear experienced during their processing. This study presents data that quantifies the influence of particle shapeJsize of three different lactose powders on their respective flow and bulk characteristics. Two of the samples differ in size but have similar shapes; the third sample is more spherical but similar in size to one of the other two samples, The results demonstrate that in addition to particle size, particle shape significantly affect the flow characteristics of a powder over a wide range of stress conditions.展开更多
Whilst caking occurs via several different mechanisms,absorption and migration of moisture is frequently the most dominant mechanism within the food and pharmaceutical industry.Fully understanding the propensity to ca...Whilst caking occurs via several different mechanisms,absorption and migration of moisture is frequently the most dominant mechanism within the food and pharmaceutical industry.Fully understanding the propensity to cake is important for minimising down-stream process issues,however most characterisation techniques assume that moisture induced caking occurs homogenously through the sample resulting in a uniformly caked powder bed.In this study,the effect of moisture induced caking on powder flowability was investigated using powder rheology.Several materials,including skimmed milk powder(SMP)and sulphated methyl ester(SME)were stored for several days under controlled humidity conditions.The flow energies,a measure of the resistance to flow,were measured at 24 h intervals using an FT4 Powder Rheometer.As the energy is measured as a function of the bed height,variations in the powder bed are also captured.The results demonstrated that caking does not always occur uniformly,instead a caked region(or crust)forms at the air-powder interface and then progresses through the powder bed.Furthermore,the strength of this caked region was shown to increase over several days before stabilising.展开更多
文摘This study is part of an ongoing project to enable the full specification of the Design Space for roller compactor systems and shows how the processing parameters influence the behaviour of the product granulate from a placebo formulation. Granulate was produced using a proprietary roller compactor by varying the compaction pressure and gap width,and the dynamic, bulk and shear properties of the resultant granulates were measured.The results demonstrate several rheological properties of the granulate, which have been shown to be closely correlated with variance in die filling and tablet strength, and are predictably influenced by the processing parameters.
文摘Powder flow behaviour is the result of countless combinations of interparticle forces of different natures: frictional,interlocking,cohesive and adhesive forces.We identify the rheological tests where one mechanism is most likely to dominate over the rest,and we propose the best descriptors of uniquely cohesive or frictional effects.We describe the procedure for a fluidisation test and the features of the results linked to powder cohesivity.We contrast these features against shear test results to determine powder frictional properties,explaining the conditions and limitations of the analysis.We use solid volume fraction and compressibility measurements to assess the extent to which the different mechanisms influence natural packing and forced flow in intermediate stress regimes.The proposed experimental protocol and framework of interpretation is applied to a wide range of powdered materials,representing typical industrial issues.The qualities of the characterisation are discussed and compared to those associated with traditional rheological testing methods.The framework successfully differentiates the effects of the various interparticle interaction mechanisms on powder flow,enabling a comprehensive prediction of powder behaviour in a variety of handling and processing settings.The metrics used are all normalised,allowing for a universal direct comparison of flowability across completely different materials.
文摘The shape and size of particles are understood to affect the bulk behaviour of powders, though there are but few studies that present quantitative information on the relationship between particle shape and the flow properties of powder. This is due in part to the lack of techniques for rapidly determining both particle shape and the range of flow characteristics that describe the response of powders to the stress and shear experienced during their processing. This study presents data that quantifies the influence of particle shapeJsize of three different lactose powders on their respective flow and bulk characteristics. Two of the samples differ in size but have similar shapes; the third sample is more spherical but similar in size to one of the other two samples, The results demonstrate that in addition to particle size, particle shape significantly affect the flow characteristics of a powder over a wide range of stress conditions.
文摘Whilst caking occurs via several different mechanisms,absorption and migration of moisture is frequently the most dominant mechanism within the food and pharmaceutical industry.Fully understanding the propensity to cake is important for minimising down-stream process issues,however most characterisation techniques assume that moisture induced caking occurs homogenously through the sample resulting in a uniformly caked powder bed.In this study,the effect of moisture induced caking on powder flowability was investigated using powder rheology.Several materials,including skimmed milk powder(SMP)and sulphated methyl ester(SME)were stored for several days under controlled humidity conditions.The flow energies,a measure of the resistance to flow,were measured at 24 h intervals using an FT4 Powder Rheometer.As the energy is measured as a function of the bed height,variations in the powder bed are also captured.The results demonstrated that caking does not always occur uniformly,instead a caked region(or crust)forms at the air-powder interface and then progresses through the powder bed.Furthermore,the strength of this caked region was shown to increase over several days before stabilising.
