[article]
| Titre : |
Fine adjustment of the melt flows in the hot runner by means of melt rotation : What can you do if shear effects upset natural manifold balancing ? |
| Type de document : |
texte imprimé |
| Auteurs : |
Reinhard Kabus, Auteur |
| Année de publication : |
2019 |
| Article en page(s) : |
p. 28-31 |
| Langues : |
Anglais (eng) |
| Catégories : |
Canaux chauffants
Empreinte (moule d'injection)
Matières plastiques -- Moulage par injection
Mouvement rotatoire
|
| Index. décimale : |
668.4 Plastiques, vinyles |
| Résumé : |
In injection molding with multi-cavity molds, shear-induced viscosity differences in the flow channels of manifold systems can result in the various mold cavities producing molded parts with different properties – in spite of natural balancing and optimum mold quality. This situation can be remedied with a fine adjustment of the melt flows, achieved using melt rotation. |
| Note de contenu : |
- Cause of a failure of uneven filling - in spite of natural balancing
- How then does melt rotation help ?
- Quality assurance also in the follow-up process
- Melt rotation - Balncing solution for all applications ?
- Where high precision in large quantities is required
- Fig. 1 : Everything is correct, but it still does sot work: a rotationally symmetrical molded part, a naturally balanced valve gate system, high mold quality - and yet the cavities are filled unevenly, with a serious impact on the required composent quality
- Fig. 2 : Cause of shear : the shear and speed profile (a) typical for laminar flow is reduced as a result of distribution (b) and deflection (c) to one side of the flow channel. This has the effect of allowing a non-homogeneous melt flow to reach the cavity the less viscous half (d) of which flows faster ; orange : lower shear, red : higher shear
- Fig. 3 : Potential scenario in the 8-fold hot runner system : as a result of distributing the melt flow with an asymmetrical shear profile, branches form in the manifold with different levels of viscosity - the outer cavities are thus filled first in this instance ; orange : lower shear, red : higher shear
- Fig. 4 : The conventional runner layout (a) is significantly easier compared to the version illustrated here in the model for melt rotation (b). However, the uneven shear profile (c) caused by the distribution of the melt flow can be converted into a symmetrical profile (f) by rotating the flow cross-sections (d) and subsequently amalgamating the melt flows (e) ; orange : lower shear, red : higher shear
- Fig. 5 : The required high quality of the molded parts is achieved by evenly and simultaneously filling cavities - facilitated by a hot runner system deploying melt rotation (Opti-Flo), which is responsible for symmetrical shear profiles in all channels ; orange : lower shear, red : higher shear
- Fig. 6 : Examples of electrical engineering components in the production of which hot runner systems with Integrated melt rotation are used (components illustrated and not to scale) |
| En ligne : |
https://drive.google.com/file/d/1hyqbD48OnNeImyQX_Jczy3Gd334bAl8x/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32551 |
in KUNSTSTOFFE INTERNATIONAL > Vol. 109, N° 5 (05/2019) . - p. 28-31
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