Melt front surface asperity and welding-defect generation in ceramic injection molding

Citation
Yh. Chung et al., Melt front surface asperity and welding-defect generation in ceramic injection molding, J MATER PR, 111(1-3), 2001, pp. 219-224
Citations number
8
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science & Engineering
Journal title
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
ISSN journal
0924-0136 → ACNP
Volume
111
Issue
1-3
Year of publication
2001
Pages
219 - 224
Database
ISI
SICI code
0924-0136(20010425)111:1-3<219:MFSAAW>2.0.ZU;2-A
Abstract
Melt front roughness was examined firstly, and it was found that an injecte d part is separated into two regions: a rough surface region and a fine sur face region. The rough surface region results from melt front asperities ge nerated by the blowout of voids at the front surface which an mixed into th e material by jetting flour in the sprue. It war also found that voids in t he sprue can be eliminated by applying counter-pressure. Secondly, the gene ration property of welding defects, weld line and voids, has been examined by counter-flow joining and their elimination criteria are obtained. It was shown that both criteria approximately coincide with each other. The weldi ng-defect elimination criterion obtained is applied to the evaluation of we lding-defect generation under various injection conditions and it was found that the criterion does not depend greatly on the asperities of the flow f ront. Furthermore, the criterion is also effective for estimating welding d efects in injection molding using a mold cavity with inserts. Finally, it w as confirmed that the above criterion approximately coincides with that in a previous paper which was obtained by the use of simple void-reducing cond itions in the joining of green ceramic blocks with artificially grooved sur faces. (C) 2001 Published by Elsevier Science B,V.