Models to Predict the Viscosity of Metal Injection Molding Feedstock Materials as Function of Their Formulation

González-Gutiérrez, Joamín; Đuretek, Ivica; Kukla, Christian; Poljšak, Andreja; Bek, Marko; Emri, Igor; Holzer, Clemens

doi:10.3390/met6060129

Cited by 43 publications

(27 citation statements)

References 40 publications

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“…The major result concerns the effect of increasing powder concentration or adding MWCNT onto the increase in the feedstocks' torque values, which is consistent with other studies [22][23][24]. As expected, the increase of powder concentration lead to higher torque value [25]; the feedstocks with 65 vol.% of powders presented the maximum torque values. Table 3.…”

Section: Optimization Process: Effects Of Powder Typesupporting

confidence: 89%

Feedstocks of Aluminum and 316L Stainless Steel Powders for Micro Hot Embossing

Emadinia

Vieira

2018

Metals

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In metal powder, shaping the preparation and characterization of the feedstock is an aspect commonly recognized as fundamental. An optimized composition is required to ensure the successful shaping of the feedstock. In this study, a commercial binder system, pure aluminum and 316L austenitic stainless-steel powders were used for micro hot embossing. The optimization process revealed that powder characteristics such as shape and the stability of the torque mixing, were important parameters. Manipulating the feedstock composition by adding multi-walled carbon nanotubes or stearic acid or using a higher powder concentration considerably influenced the torque mixing values. The steady state of torque mixing was achieved for all feedstocks. This torque behavior indicates a homogeneous feedstock, which was also confirmed by microscopic observations. Nevertheless, an extruding process was required for greater homogeneity of the aluminum feedstocks. The presence of the carbon nanotubes increased the homogeneity of green parts and reduced microcrack formation. The roughness was essentially dependent on the feedstock composition and on the plastic deformation of the elastomer die. Shaping the prepared feedstocks (with or without carbon nanotube) was achieved by the optimized powder concentrations and it did not increase by the stearic acid addition.

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Section: Optimization Process: Effects Of Powder Typesupporting

confidence: 89%

Feedstocks of Aluminum and 316L Stainless Steel Powders for Micro Hot Embossing

Emadinia

Vieira

2018

Metals

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“…To reduce assembling costs and reach more flexibility, magnetically isotropic powder is preferred. The high filler content increases the viscosity of the melted compound 7 . To avoid clogging of the nozzle, the matrix polymer should be of a high flowable material; good mechanical properties are an important aspect, too.…”

Section: Introductionmentioning

confidence: 99%

3D Printing of Polymer-Bonded Rare-Earth Magnets With a Variable Magnetic Compound Fraction for a Predefined Stray Field

Huber¹,

Abert²,

Bruckner³

et al. 2017

Sci Rep

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Additive manufacturing of polymer-bonded magnets is a recently developed technique, for single-unit production, and for structures that have been impossible to manufacture previously. Also, new possibilities to create a specific stray field around the magnet are triggered. The current work presents a method to 3D print polymer-bonded magnets with a variable magnetic compound fraction distribution. This means the saturation magnetization can be adjusted during the printing process to obtain a required external field of the manufactured magnets. A low-cost, end-user 3D printer with a mixing extruder is used to mix permanent magnetic filaments with pure polyamide (PA12) filaments. The magnetic filaments are compounded, extruded, and characterized for the printing process. To deduce the quality of the manufactured magnets with a variable magnetic compound fraction, an inverse stray field framework is developed. The effectiveness of the printing process and the simulation method is shown. It can also be used to manufacture magnets that produce a predefined stray field in a given region. This opens new possibilities for magnetic sensor applications. This setup and simulation framework allows the design and manufacturing of polymer-bonded permanent magnets, which are impossible to create with conventional methods.

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“…For lower powder loadings, the Frankel-Acrivos model [6] provides a better fit to the measured data; for higher powder loadings, the Krieger-Dougherty model [9] is better. It has to be emphasized that the fit is dependent also on the shear rate at which the data were measured and other models available in the literature might fit better [12].…”

Section: Powder Loadingmentioning

confidence: 99%

“…One main point is the shear rate at which the transition from Newtonian to shear thinning behavior takes place. This shear rate is a function of the powder loading φ p and cannot be described by the models mentioned before [12]. Geisbüsch [42] used a model which is based on the fact that the binder is sheared more when more powder is in the feedstock.…”

Section: Powder Loadingmentioning

confidence: 99%

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Rheology of Highly Filled Polymers

Kukla¹,

Đuretek²,

González-Gutiérrez³

et al. 2018

Polymer Rheology

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In many applications and/or manufacturing processes, highly filled polymers are necessary. One of these fields is powder metallurgy, where polymers or polymer mixtures are used to enable the shaping process within the production of the parts. Metal and also ceramic powders are mixed with different polymeric substances with a powder content of more than 50 vol%. Within the production, this mixture, called feedstock, has to flow into the final shape. Thus, for a proper understanding of the production processes, fundamental knowledge on the flow behavior of the feedstocks is required. For the rheology of polymers, several techniques together with the proper equipment are available. In the case of high viscosities, rotational and high-pressure capillary rheometers (HPCRs) are used. To gain reliable data, a proper measurement procedure is essential, which means that the operator has to have a deeper physical understanding of the material and the effects arising during the measurements. Therefore, this chapter gives an insight into rotational and high-pressure capillary rheometry with special emphasis on the behavior of polymers highly filled with stiff particles. Based thereon important remarks on the measurement equipment, procedure and evaluation of the measured data are provided.

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Models to Predict the Viscosity of Metal Injection Molding Feedstock Materials as Function of Their Formulation

Cited by 43 publications

References 40 publications

Feedstocks of Aluminum and 316L Stainless Steel Powders for Micro Hot Embossing

Feedstocks of Aluminum and 316L Stainless Steel Powders for Micro Hot Embossing

3D Printing of Polymer-Bonded Rare-Earth Magnets With a Variable Magnetic Compound Fraction for a Predefined Stray Field

Rheology of Highly Filled Polymers

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