ISSN:
1435-1528
Keywords:
Injection moulding
;
thermoplastic
;
freezing-off
;
mould cavity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Abstract The injection moulding of thermoplastics involves, during mould filling, flow of a hot molten polymer into a mould network, the walls of which are so cold that the polymer freezes on them. During the constant pressure drop part of the filling stage, but not during the preceding constant flow-rate part, freezing-off, that is premature blockage of the mould network by frozen polymer, is possible. A semi-quantitative analysis of such freezing-off in a mould cavity is presented here. The length-scales and time-scales of all the relevant physical processes occurring during freezing-off are identified and a criterion is obtained which enables the occurrence of freezing-off to be predicted, at least crudely. This criterion is shown to be corroborated by experimental data for the filling of a spiral mould cavity by three different polymers under a range of different operating conditions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01462498
Permalink
