This thesis is an investigation of the TPE filament for Fused Deposition Modelling (FDM) manufacturing method. All the investigations aim to optimize the quality of the filament in order to make Thermoplastic Elastomer (TPE) material possible for FDM manufacturing method. Optimization experiments were made to find out key parameters in the extrusion process that determine the quality of the filament. With the optimal parameters, further investigation of the additive content in the TPE granulate was made to solve the current problem of the filament in practical 3D printing, which the high surface friction massively affects the FDM manufacturing feasibility. The filaments were manufactured by the desktop extruder 3devo filament extruder and the surface friction tests were performed on TribotesterTM. Additionally, discussion was made to summarize the pros and cons of TPE material as well as the significance of 3D printing TPE. Potential application and benefits are mentioned for combining the property of TPE and the advantage of FDM manufacturing. Current state-of-art extrusion equipment and FDM technology are also summarized.

Extrusion is a continuous solid state deformation process which is widely used in the aluminium industry. The demand for aluminium extrudates are growing and extruders are pressurized to extrude products as fast as possible without lowering the quality of the product. Important extrusion parameters and conditions are exit temperature, extrusion speed and alloy composition. It is widely accepted in extrusion industry that extrusion surface defects increase when the extrusion speed and exit temperature are increased for a constant alloy. One of the major surface defects is the so-called die pick-up and it is presently uncertain if increase with extrusion speed (from a low 25m/min) would result in an increase of the number of die pick-up defect.Die pick-up appears like a scratch mark or comet on the surface of the extrudate which damages the appearance. Previous research suggests that second phase particles, eutectic reactions (555°C - 600°C), extrusion process conditions and die conditions may influence the cause of die pick-up. However the influencing factors for die pick-up are not well established.The research started by determining the lowest melting temperature for AA6060 alloy as this temperature limit the highest temperature above which incipient melting starts. This temperature corresponds to the eutectic melting temperature for AA6060 alloy. Eutectic melting was only detected above 610°C and therefore the exit temperature could be increased to a maximum of 610°C. For an AA6xxx alloy system the lowest melting temperature is 555°C if Mg2Si and excess silicon were present. However as Mg2Si may have fully dissolved into the solid solution, no reaction can take place.A preliminary investigation was conducted to study the characteristics of the newly installed extrusion control and monitoring system. Through this study the relationship between the set extrusion speed and the actual extrusion speed was established. It was found that the actual extrusion speed was lower than the set extrusion speed and was further complicated by the capacity limit of the extrusion pressure. Exit temperature measurements were accurate, however it was measured about 1m away from the die exit. Experiments were carried out to estimate the exit temperature drop and hence the exit temperature measurements were corrected accordingly.Thus, the aim of the present research was to establish the relationship between die pick-up and extrusion conditions (extrusion speed, exit temperature and die condition) and to propose the likely formation mechanism for die pick-up.In this research AA6060 alloy was used and was extruded at 25m/min, 30m/min, 35m/min, 40m/min and 45m/min. The exit temperature was found to increases from 542°C to 567°C. Three types of die pick-up was identified which were named as normal pick-up, die line pick-up and lump pick-up. Normal pick-up occurred regardless of the extrusion speed and exit temperature; however the amount of normal pick-up did not increase when the extrusion speed was increased. Die line pick-up occurred when the extrusion speed was 45m/min and appeared only on the die lines. Lump pick-up is not significant since it was very rare.AA6060 (0.4%Mg and 0.5%Si) alloy has about 0.27% excess silicon and therefore at 555°C, Mg2Si particles react with aluminium and excess silicon to form liquid. However normal pick-up and die line pick-up still occurred at temperatures lower and higher than 555°C and therefore it confirms that eutectic reactions do not influence formation of pick-up. Therefore die pick-up is most likely to be caused due to a mechanical process rather than a metallurgical process.

Ce travail de thèse porte sur les liens entre les conditions opératoires du procédé de mise en œuvre par mélange à l'état fondu et la structure de nanocomposites polypropylène/argile, ainsi que sur l'influence de l'état de dispersion de l'argile sur les propriétés mécaniques des matériaux obtenus. L'étude est basée sur des essais expérimentaux. Les analyses structurales sont réalisées en s'appuyant sur la rhéologie, la diffraction de rayons X ainsi que sur des observations en microscopie électronique.Les études en mélangeur interne ont montré, d'une part, que l'augmentation de la concentration en agent compatibilisant (PP-g-MA) favorise la dispersion de l'argile à l'échelle manométrique tout en augmentant la fragilité des nanocomposites, et d'autre part, que le mélange par voie mélange maître permet d'améliorer considérablement l'état de dispersion comparativement à la voie directe. Les essais réalisés en extrusion bivis corotative ont permis de mettre en évidence l'impact de la vitesse de rotation des vis (N), du débit d'alimentation (Q) et de la température de régulation (Trég) sur l'état de dispersion. L'influence de ces trois variables peut être décrite à l'aide d'un paramètre unique : l'énergie mécanique spécifique (EMS). L'accroissement de l'EMS entraîne une augmentation du niveau d'exfoliation jusqu'à une valeur critique au-delà de laquelle les conditions opératoires ne semblent plus influencer l'état de dispersion. Une relation entre le module de Young des nanocomposites et le niveau d'exfoliation a été établie. Le logiciel LUDOVIC© nous a permis de montrer que l'EMS permet également une bonne description de la progression de l'état de dispersion le long du profil d'extrusion. Enfin, l'étude du comportement thixotrope des nanocomposites à l'état fondu a notamment permis de comprendre que le principe de superposition temps-température ne s'applique pas systématiquement aux nanocomposites étant donné leur caractère évolutif.

Defects in polyethylene film are often caused by contaminant particles in the polymer melt. In this research, particle properties obtainable from in-line melt monitoring, combined with processing information, are used to predict film defect properties. “Model” particles (solid and hollow glass microspheres, aluminum powder, ceramic microspheres, glass fibers, wood particles, and cross-linked polyethylene) were injected into low-density polyethylene extruder feed. Defects resulted when the polyethylene containing particles was extruded through a film die and stretched by a take-up roller as it cooled to form films 57 to 241mm in thickness. Two off-line analysis methods were further developed and applied to the defects: polarized light imaging and interferometric imaging. Polarized light showed residual stresses in the film caused by the particle as well as properties of the embedded particle. Interferometry enabled measures of the film distortion, notably defect volume. From the images, only three attributes were required for mathematical modeling: particle area, defect area, and defect volume. These attributes yielded two ”primary defect properties”: average defect height and magnification (of particle area). For all spherical particles, empirical correlations of these properties were obtained for each of the two major types of defects that emerged: high average height and low average height defects. Analysis of data for non-spherical particles was limited to showing how, in some cases, their data differed from the spherical particle correlations. To help explain empirical correlations of the primary defect properties with film thickness, a simple model was proposed and found to be supported by the high average height defect data: the “constant defect volume per unit particle area” model. It assumes that the product of average defect height and magnification is a constant for all film thicknesses. A numerical example illustrates how the methodology developed in this work can be used as a starting point for predicting film defect properties in industrial systems. A limitation is that each prediction yields two pairs of primary defect property values, one pair for each defect type. If it is necessary to identify the dominant type, then measurement of a length dimension of sufficient defects in the film is required.

Defects in polyethylene film are often caused by contaminant particles in the polymer melt. In this research, particle properties obtainable from in-line melt monitoring, combined with processing information, are used to predict film defect properties. “Model” particles (solid and hollow glass microspheres, aluminum powder, ceramic microspheres, glass fibers, wood particles, and cross-linked polyethylene) were injected into low-density polyethylene extruder feed. Defects resulted when the polyethylene containing particles was extruded through a film die and stretched by a take-up roller as it cooled to form films 57 to 241mm in thickness. Two off-line analysis methods were further developed and applied to the defects: polarized light imaging and interferometric imaging. Polarized light showed residual stresses in the film caused by the particle as well as properties of the embedded particle. Interferometry enabled measures of the film distortion, notably defect volume. From the images, only three attributes were required for mathematical modeling: particle area, defect area, and defect volume. These attributes yielded two ”primary defect properties”: average defect height and magnification (of particle area). For all spherical particles, empirical correlations of these properties were obtained for each of the two major types of defects that emerged: high average height and low average height defects. Analysis of data for non-spherical particles was limited to showing how, in some cases, their data differed from the spherical particle correlations. To help explain empirical correlations of the primary defect properties with film thickness, a simple model was proposed and found to be supported by the high average height defect data: the “constant defect volume per unit particle area” model. It assumes that the product of average defect height and magnification is a constant for all film thicknesses. A numerical example illustrates how the methodology developed in this work can be used as a starting point for predicting film defect properties in industrial systems. A limitation is that each prediction yields two pairs of primary defect property values, one pair for each defect type. If it is necessary to identify the dominant type, then measurement of a length dimension of sufficient defects in the film is required.

This study investigated the use of extrusion technology and fat replacers to produce high protein, low fat Cheddar cheese. In chapter 3, four different fat replacers were tested at the highest concentration level of each, as recommended by the manufacturers for low fat cheese, to investigate the change in cheese texture and optimize extruder conditions. In addition, the press time/pressure combinations of the extruded cheeses were optimized. The fat replacers and extruder conditions that were effective in improving the texture of low fat cheese were then used in chapter 4. In chapter 4, three fat replacers were used at three different concentrations (lowest, middle and highest) as recommended by the manufacturers for replacing fat in cheese. The fat replacers were microcrystalline cellulose (MCC 1) (0.125%, 1.06% and 2%), whey protein concentrate (WPC 2) (0.50%, 0.75% and 1%) and whey protein concentrate (WPC 1) (0.40%, 2.20% and 4%). These fat replacers were effective in improving the texture of low fat cheese as determined from the results of chapter 3. The extruded cheese samples with and without fat replacers were analyzed for texture at three different time periods (1 day, 1 week, and 1 month). None of the fat replacers used were effective in improving the texture of low fat cheese significantly. Since none of the treatments statistically improved the texture of low fat cheese, in the next part of the study, extrusion alone and WPC 1 at the middle concentration were then used to produce low fat cheese with high protein content by blending low moisture aged Cheddar cheese and nonfat cheese. Extrusion of cheese blends with or without fat replacer yielded cheese with high protein level. It was concluded from the study that the fat replacers we used were not effective in improving the texture but extrusion of aged Cheddar cheese with nonfat cheese can yield high protein cheese.

This study investigates analytically and experimentally extrusion processes of magnesium hollow tubes by a single-cylinder extrusion machine and double-cylinder extrusion machine. The first part of this study is to conduct analysis and experiment of hollow helical tube extrusion by single-cylinder extrusion machine. Firstly, a design criterion is proposed to determine the forming parameters and discuss the effects of product size, extrusion ratio, billet length, etc. on the mandrel surface stress. The effects of the die bearing part length, angle of rotation, extrusion speed, initial temperature, petal number, etc. on the radial filling ratio are also investigated. Better parameters are chosen from analytical results to conduct hot extrusion experiments for obtaining sound products. Microstructure observation and hardness test are conducted at the cross-section of the product. The experimental values of extrusion load and product¡¦s dimensions are compared with the analytical values to verify the validity of the analytical models. The second part of this study is to conduct analysis and experiment of hollow tubes extrusion by a double-cylinder extrusion machine. The effects of extrusion ratio, billet length, mandrel diameter, etc. on the drawing force on the mandrel and critical conditions without mandrel fracture are discussed.

High feed costs and increasing demand for fishmeal have intensified the search for alternative protein sources which are needed to allow world aquaculture to continue expanding. A severely underused marine resource is processing wastes of various types of seafood, which are often disposed of at great cost. Therefore, this study was conducted to evaluate three different types of seafood processing wastes as potential feed ingredients for the red drum (Sciaenops ocellatus). The three processing wastes evaluated were heads and shells from Penaeid shrimp, and viscera and skeletal remains from filleted black drum (Pogonias cromis) and channel catfish (Ictaluras punctatus). These wastes were blended with soybean meal in a 40:60 ratio, dry extruded and dried to produce stable ingredients. All three byproduct meals produced had crude protein levels ranging from 45 to 50 percent. Two feeding trials were conducted to evaluate the different processing waste byproduct meals in comparison to menhaden fishmeal. A digestibility trial was conducted with sub-adult red drum which led to the computation of apparent digestibility coefficients (ADCs) for organic matter, protein, lipid and energy for each of the byproduct meals. Each byproduct meal had relatively high ADC values that were generally similar to those of menhaden fishmeal. A comparative growth trial with red drum was then conducted in which experimental diets were formulated with the three byproduct meals replacing menhaden fishmeal on an equal-digestible-protein basis at levels of 65 percent, 80 percent, or 95 percent. Juvenile red drum were fed the various diets for 8 weeks in a brackish (6 plus/minus 1 ppt) water recirculating system after which weight gain, survival, feed efficiency, as well as whole-body proximate composition and condition indices were measured. All three of the byproduct meals could replace up to 65 percent of the protein provided by fishmeal without adversely affecting performance of red drum. However, the shrimp byproduct consistently provided the highest performance values at 80 percent replacement. The catfish byproduct yielded the lowest fish performance at all levels. This study indicates that dry extrusion of seafood processing wastes can be used to replace a considerable amount of fishmeal in feeds for red drum.

This paper describes a method by means of FE code DEFORMTM-2D to simulate the formation of central bursting defects in extrusion processes; the effect of various extrusion parameters such as half die angle, reduction in area, friction factor, and strain hardening exponent on the maximum damage value is examined. The differences between various ductile fracture criteria are compared and critical damage value(CDV) of the material AA6061 is found. In addition, we get the strength coefficient(K), strain hardening exponent(n), CDV and friction factor(m) by material tests, such as uniform tensile test, notched tensile test, compression test, and ring compression test. Finally, the cold multistage extrusion experiment was conducted to verify the accuracy of the finite element simulations. From the continuous three pass extrusion experimental data, no fracture in the center of the extruded product was found. From the analytical data, it was known that the maximum damage value 1.0479 for third pass extrusion was small than critical damage value 1.068, thus, central bursting defects didn¡¦t occur in extrusion processes.

The microstructures and mechanical properties of the AZ31 Mg tubes fabricated by one-pass forward piercing tube extrusion operated at 250-400oC and 10-2-100 s-1 are examined. The grain size is refined from the initial ~75