Influence of rotor on extrusion pressure

Fekete, Roman; Jaššo, Igor; Peciar, Marián; Molnár, A.

doi:10.1016/j.powtec.2004.02.009

Cited by 5 publications

(3 citation statements)

References 3 publications

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“…It has been used to develop "pragmatic" models for paste extrusion in non-capillary geometries such as multi-hole dies [4], screw extruders [5], and cylindrical extrusion [6], where the accuracy reflects the uncertainty in the characterization and represents a useful tool for design calculations in the absence of reliable constitutive models [7]. Also, Fekete et al [8] describe changes in extrusion pressure in an extruder of special design such that as rotor speed increases, the resulting pressure in the extruder decreases. They justify this by the change in the apparent viscosity of the paste, which is a function of the shear strain rate tensor, the components of which are affected just by the rotor effect.…”

Section: Theoretical Analysismentioning

confidence: 99%

Influence of Die Length on Extrusion Pressure and Extrudate Surface Quality

Uličná,

Fekete,

Juriga

et al. 2023

Strojnícky Časopis - Journal of Mechanical Engineering

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The extrusion process is very popular in industry. Nowadays, extrusion is also closely associated with the 3D printing process, but this article is focused on extrusion, as a process that is mainly associated with spheronization. The extrusion product is shaped in such a way that it is suitable for the ongoing spheronization process. With this two-step extrusion-spheronization (E–S) process, it is possible to create pellets with controlled high sphericity, which are desired in tablet and capsule production due to their easily characterized (and controlled) dosage profile and good flow properties. During extrusion, it is important to monitor several parameters. This post is dedicated to one of them and that is the length of the die and its effect on the extrusion pressure as well as the effect on the extrudate surface quality.

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Section: Theoretical Analysismentioning

confidence: 99%

Influence of Die Length on Extrusion Pressure and Extrudate Surface Quality

Uličná,

Fekete,

Juriga

et al. 2023

Strojnícky Časopis - Journal of Mechanical Engineering

Self Cite

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“…During steady fabrication of structures, the XY table velocity should be equivalent to the filament extrusion velocity. The extrusion velocity can be determined from the Benbow-Bridgewater equation (Benbow et al, 1987) as modified for a conical die entry (Raupp-Pereira et al, 2007;Fekete et al, 2004), but at present not all the parameters are known for this system. However, from this equation, it is known that the filament extrudate velocity is limited by the paste characteristics and the overall extrusion pressure drop which determines the press load and this in turn limits the XY table path velocity (the linear motor table can reach 100 mms 2 1 ).…”

Section: Filament Diametermentioning

confidence: 99%

Extrusion freeforming of millimeter wave electromagnetic bandgap (EBG) structures

Lee

Yang

et al. 2009

Rapid Prototyping Journal

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PurposeThe aim of this paper is to provide an easy method of extrusion freeforming to fabricate microwave electromagnetic bandgap (EBG) crystals. EBG crystals are periodic dielectric structures that can block wave propagation and generate a bandgap. These crystals can be used in high capability antennae, electromagnetic wave semiconductors, microresonators, high‐reflectivity mirrors and polarizing beam splitters.Design/methodology/approachThe effects of extrusion process parameters and paste characteristics were investigated. Finally, one‐period and two‐period woodpile EBG crystals with bandgaps in the frequency region of 90‐110 GHz were fabricated and the bandgap was measured.FindingsThe filament diameter is influenced by whether extrusion is carried out with or without a substrate and by the free fall‐distance from the nozzle. The quality of lattice structures is dependent on paste flow and properties. A ceramic paste with 60 vol. % (the fraction of ceramic powder based on solvent‐free polymer) was well suited to fabrication. The solvent content also influenced the fabrication. The experimental results show that under ∼12 per cent solvent mass fraction in the paste and relatively high extrusion ram velocity (more than 0.014 mm/s) at a pressure of 14 MPa, samples with high quality were fabricated.Originality/valueThis paper demonstrates that the rapid prototyping method of extrusion freeforming can be applied for the fabrication of EBG crystals from ceramic powders and the important factors which influence the product quality are identified.

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“…Isso significa que ao adentrar a zona estática, a pasta cimentícia adquire uma viscosidade aparente muito superior àquela da mesma pasta ainda situada na câmara de extrusão, o que obstrui a extrusão do material. Tal dificuldade foi superada mediante a extensão da rosca até as proximidades do bocal (FEKETE 2004) e pela utilização do mesmo polímero, mas com menor peso molecular, o HEC-LR (PM~9,0.10 4 ), em teor de até 1,5% em peso do CPII-E. Para não influenciar na plasticidade satisfatória que o HEC propiciou à mistura, o Na-CMC foi substituído pela sílica como espessante.…”

Section: Formulaçõesunclassified

Contribuições para a ciência e engenharia de materiais cimentícios: processamento, durabilidade e resistência mecânica.

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Influence of rotor on extrusion pressure

Cited by 5 publications

References 3 publications

Influence of Die Length on Extrusion Pressure and Extrudate Surface Quality

Influence of Die Length on Extrusion Pressure and Extrudate Surface Quality

Extrusion freeforming of millimeter wave electromagnetic bandgap (EBG) structures

Contribuições para a ciência e engenharia de materiais cimentícios: processamento, durabilidade e resistência mecânica.

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