LIQUID PHASE MIGRATION IN EXTRUSION OF AQUEOUS ALUMINA PASTE FOR FREEZE-FORM EXTRUSION FABRICATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1861-1866 ◽  
Author(s):  
HONGJUN LIU ◽  
MING C. LEU
Keyword(s):  
Liquid Phase ◽  
Dead Zone ◽  
Extrusion Process ◽  
Extrusion Force ◽  
Transient Stage ◽  
Steady Stage ◽  
Paste Extrusion ◽  
Force Data ◽  
Force Profiles ◽  
Key Parameter

Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing technique that extrudes highly ceramic loaded aqueous paste along 3D contours for complex ceramic part fabrication. The phenomenon of liquid phase migration (LPM) in paste extrusion process will result in variation of liquid content in paste and consequently problems in processing and non-uniform properties of ceramic parts. It is necessary to understand the LPM phenomenon in FEF process. In this paper, the effect of liquid phase migration on extrusion of aqueous alumina paste was investigated for FEF process. The water content and extrusion force data were collected for a series of ram velocities. According to the extrusion force profiles, the extrusion process can be divided into four stages: compaction stage, transient stage, steady stage and dead zone stage. The results show that ram velocity is the key parameter for occurrence of liquid phase migration phenomenon and there is a velocity threshold above which the liquid phase migration will not happen.

Investigation on Paste Extrudate Features in Ram Extrusion Process

2012 ◽  
Vol 159 ◽  
pp. 146-150
Author(s):  
Hong Jun Liu ◽  
Dong Jian Li ◽  
Ya Min Li
Keyword(s):  
Liquid Phase ◽  
Average Diameter ◽  
Extrusion Process ◽  
Nozzle Diameter ◽  
Considerable Degree ◽  
Extrusion Force ◽  
Liquid Content ◽  
Ceramic Component ◽  
Paste Extrusion ◽  
Experimental Works

The precision of ceramic component gotten by some Solid Freeform Fabirication processes based on paste extrusion is dependent to a considerable degree on paste extrudate. To get clearer understanding about paste extrudate, the experimental works were carried out to investigate some important extrudate features for ram extrusion process in this paper. The velocity, diameter, liquid content and mass of extrudate of alunima paste by ram extrusion were studied. The liquid content of extrudate tests show that the occurance liquid phase migration depends on the ram velocity. Without liquid phase migration, the extrudate velocities have a corresponding relations to extrusion force. The dilation of extrudate occurs in commonly used ram velocities. So extrudate velocities should not be calculated by nozzle diameter but by the average diameter of dilated extrudate. The mass of extrudate in the very end of extrusion is greatly reduced and should not be used.

Research on Extrusion Velocity in Freeform Extrusion Fabrication of Aqueous Alumina Paste

2009 ◽  
Vol 419-420 ◽  
pp. 125-128 ◽  
Author(s):  
Hong Jun Liu ◽  
Ming C. Leu
Keyword(s):  
Solid Freeform Fabrication ◽  
Extrusion Process ◽  
Extrusion Force ◽  
High Solids ◽  
Transient Stage ◽  
Freeform Fabrication ◽  
Solids Loading ◽  
High Solids Loading ◽  
Steady Stage ◽  
Velocity Input

The Freeform Extrusion Fabrication (FEF) is a Solid Freeform Fabrication process, which fabricates 3D ceramic green parts by extruding an aqueous ceramic paste of high solids loading. The extrusion velocity is a very important parameter and should be better understood. In this paper, experiments were carried out to investigate extrusion velocity in FEF extrusion process of aqueous alumina paste. It is found that the extrusion velocity has a corresponding relationship with extrusion force. The extrusion run can be divided into 4 stages: compaction stage, transient stage, steady stage and stop stage. The step ram velocity input was applied in FEF process and improved the extrusion velocity profiles in transient stage.

Influence of Liquid Phase Migration on Intermittent Extrusion of Aqueous Al2O3 Paste

2011 ◽  
Vol 189-193 ◽  
pp. 177-180
Author(s):  
Hong Jun Liu
Keyword(s):  
Liquid Phase ◽  
Solid Freeform Fabrication ◽  
Extrusion Process ◽  
Fabrication Process ◽  
Extrusion Pressure ◽  
Strong Impact ◽  
Fabrication Method ◽  
Liquid Content ◽  
Freeform Fabrication ◽  
Paste Extrusion

Extrusion Freeform Fabrication Process (EFF) is an environmentally friendly solid freeform fabrication method that uses aqueous pastes to fabricate ceramic-based components. The Liquid Phase Migration (LPM) causes variation in liquid content and consequently problems in the paste extrusion. To get uniform ceramics parts with desired composition, the LPM should be avoided in extrusion process. This paper investigated the influence of LPM on extrusion process for aqueous alumina paste in EFF process. It shows that the liquid phase migration occurs in Freeform Extrusion Fabrication process and has a strong impact on extrusion pressure. The LPM can be characterized by the extrusion pressure-ram displacement profiles. The liquid phase migration becomes more serious in intermittent extrusion at low ram velocity.

Research on Influence of Process Parameters on Sheet Metal Extrusion Force

2009 ◽  
Vol 16-19 ◽  
pp. 515-519
Author(s):  
Hua Xiang ◽  
Xin Cun Zhuang ◽  
Zhen Zhao
Keyword(s):  
Sheet Metal ◽  
Process Parameters ◽  
Fem Simulation ◽  
Extrusion Process ◽  
Orthogonal Experimental Design ◽  
Extrusion Force ◽  
Influence Of Process Parameters ◽  
Tool Shape ◽  
Simulation And Experiment ◽  
Metal Extrusion

Extrusion force plays a significant role on sheet metal extrusion process. It is characterized by various process parameters including material properties, extrusion ratio, friction, tool shape etc. In this paper, a reasonable FEM model of sheet metal extrusion process was established and validated by comparing the results of simulation and experiment firstly. Based on the reliable model, the effect on extrusion force of various process parameters was investigated with orthogonal experimental design combined FEM simulation. The work presented in this paper has laid certain foundation for further work of modeling and optimizing extrusion force.

scholarly journals Effect of Process Parameters and Definition of Favorable Conditions in Multi-Material Extrusion of Bimetallic AZ31B–Ti6Al4V Billets

2020 ◽  
Vol 10 (22) ◽  
pp. 8048
Author(s):  
Daniel Fernández ◽  
Alvaro Rodríguez-Prieto ◽  
Ana María Camacho
Keyword(s):  
Influencing Factor ◽  
Element Model ◽  
Extrusion Process ◽  
Extrusion Force ◽  
Core Diameter ◽  
The Core ◽  
Ram Speed ◽  
Definition Of ◽  
Favorable Conditions ◽  
Influential Parameters

This paper investigates the extrusion process to manufacture bimetallic cylinders combining a magnesium alloy core (AZ31B) and a titanium alloy sleeve (Ti6Al4V) of interest in aeronautical applications. A robust finite element model has been developed to determine the most influential parameters and to study the effect of them on the extrusion force and damage induced by means of Design of Experiments (DOE) and Taguchi method. The results show that the most influential parameters in the extrusion forces are the friction between sleeve and container/die and the height of the cylinder; and the less influential ones are the process temperature and ram speed. Moreover, minimum values of forces along with low damage can be reached by favorable interface contact conditions, minimizing the friction at the core-container/die interface, as the main influencing factor; followed by the geometrical dimensions of the billet, being the billet height more important when paying attention to the minimum forces, and being the core diameter when considering the minimum damage as the most important criterion. The results can potentially be used to improve the efficiency of this kind of extrusion process and the quality of the extruded part that, along with the use of lightweight materials, can contribute to sustainable production approaches.

Extrusion Process Modeling for Aqueous-Based Ceramic Pastes—Part 2: Experimental Verification

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Mingyang Li ◽  
Lie Tang ◽  
Robert G. Landers ◽  
Ming C. Leu
Keyword(s):  
Constitutive Model ◽  
Response Time ◽  
Rapid Change ◽  
Experimental Studies ◽  
Extrusion Process ◽  
Experimental Results ◽  
Constitutive Law ◽  
Extrusion Force ◽  
Air Bubble ◽  
Highly Nonlinear

In the Part 1 paper, a constitutive law for the extrusion process of aqueous-based ceramic pastes was created. In the study described herein, a capillary rheometer was used to calibrate the viscosity of an alumina paste, and a single extruder system was used to conduct extrusion experiments to validate the constitutive model. It is shown that the extrusion response time and its change both depend on the amount of air in the extruder and the magnitude of the extrusion force. When the extrusion force is small, the rapid change of extrusion response time gives the extrusion dynamic an apparent quadratic response. When the extrusion force is large, the extrusion response time changes slowly, and is dominated by a first-order response. Air bubble release was observed in some of the experiments. A series of simulation and experimental studies were conducted to validate the predictive capabilities of the constitutive model for both steady-state and transient extrusion force behaviors. Good agreements between the simulation and experimental results were obtained. The experimental results demonstrate that the constitutive model is capable of capturing the characteristics of the highly nonlinear response at low extrusion forces and the air bubble release phenomenon. The numerical studies show that the decrease in the extrusion force during an air bubble release depends on the volume of the air bubble.

Effects of Multi-Step Welding Chamber on Extrusion Product Quality and Die Strength

2010 ◽  
Vol 44-47 ◽  
pp. 311-315
Author(s):  
Hao Chen ◽  
Guo Qun Zhao ◽  
Cun Sheng Zhang ◽  
Dao Sheng Wen
Keyword(s):  
Product Quality ◽  
Maximum Stress ◽  
Metal Flow ◽  
Extrusion Process ◽  
Porthole Die ◽  
Die Life ◽  
Die Extrusion ◽  
Extrusion Product ◽  
Porthole Die Extrusion ◽  
Key Parameter

The shape of welding chamber is a key parameter in flat porthole die extrusion process, which influences product quality and die life-span directly. In this paper, by means of numerical simulation of the extrusion process for an aluminum hollow profile, the effects of multi-step welding chamber on metal flow and die strength have been investigate. The numerical results revealed that the multi-step welding chamber was effective to balance metal flow in the die cavity. In addition, with an increasing step of welding chamber, the maximum stress and deflection of the lower die decreased, while the deflection of the mandrel kept almost unchanged and the maximum stress of upper die increased.

The Effect of Lubricant Viscosity in Cold Work Forward Extrusion

2014 ◽  
Vol 554 ◽  
pp. 291-295
Author(s):  
Samion Syahrullail ◽  
Shunpei Kamitani ◽  
Kenji Nakanishi
Keyword(s):  
Sliding Friction ◽  
Pure Aluminum ◽  
Cold Work ◽  
Metal Flow ◽  
Extrusion Process ◽  
High Viscosity ◽  
Extrusion Force ◽  
Workpiece Surface ◽  
Forward Extrusion ◽  
Lubricant Viscosity

In cold work extrusion, lubricants play an important role in lubricating the tool and workpiece surfaces, preventing metal-to-metal contact and reducing sliding friction, so that the workpiece can be extruded smoothly without severe wear due to lubricant starvation. In this paper, the influence of lubricant viscosity in cold work forward extrusion was investigated. The lubricants were additive-free, paraffinic mineral oil, which may have low, medium or high viscosity. The workpiece material was pure aluminum A1100, extruded with extrusion ratio of 3. The analysis focused on extrusion force, workpiece surface roughness after the extrusion process and the metal flow in the deformation zone of the workpiece. Using the visioplasticity method, the sliding velocity was calculated from the metal flow. Results showed that, the higher the lubricant viscosity, the lower the extrusion force generated. However, a high-viscosity lubricant produces coarser workpiece surface conditions after the extrusion process.

scholarly journals The Elucidation of the Molecular Mechanism of the Extrusion Process

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4278
Author(s):  
Joanna Doskocz ◽  
Paulina Dałek ◽  
Magdalena Przybyło ◽  
Barbara Trzebicka ◽  
Aleksander Foryś ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lipid Bilayer ◽  
Molecular Mechanisms ◽  
Flicker Noise ◽  
Extrusion Process ◽  
Extrusion Force ◽  
Bending Rigidity ◽  
Polycarbonate Membrane ◽  
Noise Spectroscopy ◽  
Liposome Suspension

Extrusion is a popular method for producing homogenous population of unilamellar liposomes. The technique relies on forcing a lipid suspension through cylindrical pores in a polycarbonate membrane. The quantification of the extrusion and/or recalibration processes make possible the acquisition of experimental data, which can be correlated with the mechanical properties of the lipid bilayer. In this work, the force needed for the extrusion process was correlated with the mechanical properties of a lipid bilayer derived from other experiments. Measurements were performed using a home-made dedicated device capable of maintaining a stable volumetric flux of a liposome suspension through well-defined pores and to continuously measure the extrusion force. Based on the obtained results, the correlation between the lipid bilayer bending rigidity and extrusion force was derived. Specifically, it was found that the bending rigidity of liposomes formed from well-defined lipid mixtures agrees with data obtained by others using flicker-noise spectroscopy or micromanipulation. The other issue addressed in the presented studies was the identification of molecular mechanisms leading to the formation of unilamellar vesicles in the extrusion process. Finally, it was demonstrated that during the extrusion, lipids are not exchanged between vesicles, i.e., vesicles can divide but no membrane fusion or lipid exchange between bilayers was detected.

Measurement and interpretation of spatially registered bar-forces in LC refining

2020 ◽  
Vol 35 (4) ◽  
pp. 600-610
Author(s):  
Matthias Aigner ◽  
James Olson ◽  
Peter Wild
Keyword(s):  
Work Force ◽  
Force Sensor ◽  
Edge Length ◽  
Rotary Encoder ◽  
Critical Gap ◽  
Early Peak ◽  
Geometric Variables ◽  
Force Data ◽  
Force Profiles ◽  
Shed Light

AbstractA high resolution rotary encoder and a piezo electric force sensor are implemented in a 16-inch laboratory-scale low consistency refiner to explore the effect of plate gaps on bar-force profiles. The sensor replaces a short length of a stator bar and measures normal and shear forces applied during the passage of each rotor bar. The rotary encoder data is used to locate the rotor bars relative to the stator bar in which the sensor is located. Previous work with this type of force sensor focuses primarily on the distribution of the maximum force measured during the passage of each rotor bar over the sensor or bar passing event, BPE. In this work, force profiles for bar passing events are registered to the position of rotor bars relative to the stator bar in which the sensor is located. These registered force profiles are measured for a range of plate gaps and two different pulp furnishes. The angular reference provided by the encoder makes it possible to generate mean force profiles. As force data for individual BPEs is highly variable, these mean force profiles have potential to shed light on the fundamental mechanisms of mechanical refining. For large gaps, there is a late peak in the force profiles that occurs toward the end of the bar passing event. For gaps that are less than the critical gap, below which fiber cutting occurs, there is an early peak in the force profiles that occurs at the start of the bar passing event. It is hypothesized that the early peak represents the corner force and, therefore, that corner force is causal in the onset of fiber cutting. To explore this hypothesis, a model is presented connecting corner force and friction force to the progression geometric variables during the bar passing event such as the bar edge length engaged at any point in the bar passing event and the area covered by the rotor bar on the force sensor at any point in the bar passing event.

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