Dry grinding in planetary ball mills: Evaluation of a stressing model

Burmeister, Christine; Titscher, Larissa; Breitung‐Faes, Sandra; Kwade, Arno

doi:10.1016/j.apt.2017.11.001

Cited by 55 publications

(58 citation statements)

References 19 publications

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“…Figure 3 shows the effect of the polymer feed load on the temporal evolution of the particle size. As expected, a slower reduction of x 50,3 over time is observed with an increase in the feed load [46,47,60]. For prolonged grinding (c.f.…”

Section: Resultssupporting

confidence: 53%

“…The acceleration, α , is calculated using the effective radius of the revolution, R , which is 70 mm for the used mill, and the angular velocity, ω, to the power of 2. Using the parameters described above, the maximum stress energy, E kin , of a single grinding bead is around 11.8 mJ, however, the effective stress energy a particle experiences typically will be much lower (see e.g., [46,47]). The temperature inside of the grinding vessel was measured every 20 min cycle for 240 min (i.e., 12 grinding cycles); after 60 min, the temperature remained at 40 °C for the rest of the experiment.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Spherical Polybutylene Terephthalate (PBT)—Polycarbonate (PC) Blend Particles by Mechanical Alloying and Thermal Rounding

Dechet

Bonilla

Lanzl³

et al. 2018

Polymers

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In this study, the feasibility of co-grinding and the subsequent thermal rounding to produce spherical polymer blend particles for selective laser sintering (SLS) is demonstrated for polybutylene terephthalate (PBT) and polycarbonate (PC). The polymers are jointly comminuted in a planetary ball mill, and the obtained product particles are rounded in a heated downer reactor. The size distribution of PBT–PC composite particles is characterized with laser diffraction particle sizing, while the shape and morphology are investigated via scanning electron microscopy (SEM). A thorough investigation and characterization of the polymer intermixing in single particles is achieved via staining techniques and Raman microscopy. Furthermore, polarized light microscopy on thin film cuts enables the visualization of polymer mixing inside the particles. Trans-esterification between PBT and PC during the process steps is investigated via vibrational spectroscopy and differential scanning calorimetry (DSC). In this way, a new process route for the production of novel polymer blend particle systems for SLS is developed and carefully analyzed.

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Section: Resultssupporting

confidence: 53%

Section: Methodsmentioning

confidence: 99%

Spherical Polybutylene Terephthalate (PBT)—Polycarbonate (PC) Blend Particles by Mechanical Alloying and Thermal Rounding

Dechet

Bonilla

Lanzl³

et al. 2018

Polymers

View full text Add to dashboard Cite

show abstract

“…The results revealed that, during the milling process, the size of the milling media changed, whereas the material composing the media remained unchanged. Milling media are simulated as discrete elements and the compression and shear forces for each impact are determined by Hertz and Mindlin's contact model, and the resulting velocity is calculated according to Newton's law of motion in the DEM simulation [22]. In order to explore the motion of the balls in a ball milling process, we performed the ball impact energy estimated by a DEM simulation.…”

Section: Resultsmentioning

confidence: 99%

Effect of Different Milling Media for Surface Coating on the Copper Powder Using Two Kinds of Ball Mills with Discrete Element Method Simulation

et al. 2020

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This study investigated the effect of three different ball materials on the metal-based carbon nanotube (CNT) composites used as surface coatings on metal-powder to fabricate high-quality nanocomposites. The effect of ball material, different rotation speeds, and milling times on the coating characteristics of the metal-based nanocomposite were studied. The mechanical dry coating was used to fabricate CNT coatings on the surface of copper powder particles via two different ball milling machines such as a traditional ball mill and a stirred ball mill. We explored the effect of the milling media of the ball mill under different ball materials and ball sizes on the metal powder during the ball milling process with DEM simulation. Using discrete element method simulation to obtain the average velocity, force, and, kinetic energy of the milling media in a low and high energy ball mills.

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“…However, in-situ observations have not shown signs of balls leaving the vial surface to make clear single collisions; the actual situation is much more complex with multiple types of ball-ball and ball-vial interactions [7, 8, 9]. Nowadays, most of the studies use numerical simulations of the collective three-dimensional ball motion based on the Discrete Element Model (DEM) [10, 11, 12], since it is possible to quantify in a more precise way the effects of successive small collisions between balls, the lack of single ball-wall collisions and the slipping and rolling of balls, situations that occur in real milling conditions [11, 13].…”

Section: Introductionmentioning

confidence: 99%

“…In all these studies, the key role played by the rotational speed of the planetary mill and the number and nature of balls (and indirectly the ball-to-powder ratio, BPR) have always been highlighted since these parameters determine greatly the rate of the energy transfer to the powder material. Nevertheless, the influence of the ratio ( k ) between the rotational speed of the supporting disc ( ω d ) and vials ( ω v ), ( k = -ω v /ω d ), on the milling efficiency has not been frequently addressed [5, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17]. The main reason is that most commercial planetary mills, especially at a laboratory scale, are characterised by a fixed transmission ratio that sets this k parameter to a value of approximately 1.…”

Section: Introductionmentioning

confidence: 99%

Effects of the speed ratio on the efficiency of planetary mills

Real

Gotor

2019

Heliyon

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The ignition time (t ig ) of the mechanically induced self-sustaining reaction (MSR) process involving the formation of TiB 2 from Ti/2B elemental mixtures was used to study the influence of the ratio ( k = -ω v /ω d ) between the rotational speed of the supporting disc ( ω d ) and vials ( ω v ) on the milling efficiency of a Pulverisette 4 planetary mill. The variation of the inverse of the ignition time (1/t ig ), which is directly related to the milling power provided by the planetary mill, with the process conditions has shown that it is not possible to find a single k value as optimal independently of the experimental conditions used ( ω d and the ball-to-powder ratio, BPR). Moreover, it was observed that the lowest milling efficiency (longer t ig values) was found for k = 1, which is the usual value employed in routine laboratory works. The best efficiencies were found for the larger k values (2.5 or 3). At lower ω d , the shortest t ig was obtained for k = 2.5 and at higher ω d for k = 3, independently of BPR.

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Dry grinding in planetary ball mills: Evaluation of a stressing model

Cited by 55 publications

References 19 publications

Spherical Polybutylene Terephthalate (PBT)—Polycarbonate (PC) Blend Particles by Mechanical Alloying and Thermal Rounding

Spherical Polybutylene Terephthalate (PBT)—Polycarbonate (PC) Blend Particles by Mechanical Alloying and Thermal Rounding

Effect of Different Milling Media for Surface Coating on the Copper Powder Using Two Kinds of Ball Mills with Discrete Element Method Simulation

Effects of the speed ratio on the efficiency of planetary mills

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