Maro Publications

Blow Molding: Molds

Notes

*7/3/2013 
from 7/3/2013

Maro Encyclopedia

Comments

Patent Abstracts

Patent Titles

Blow Molding

Molds

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Notes

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1. As a result of environmental and other concerns, plastic containers, more specifically polyester and even more specifically polyethylene terephthalate (PET) containers are now being used more than ever to package numerous commodities previously supplied in glass containers. Manufacturers and fillers, as well as consumers, have recognized that PET containers are lightweight, inexpensive, recyclable and manufacturable in large quantities. As a result, blow-molded plastic containers have become commonplace in packaging numerous commodities.

Molds used to form such containers generally include four key features; A) a molding surface to form the container shape, B) vents formed in the cavity to atmosphere that allow air to egress the cavity as a preform inflates within the mold and ingress as the container exits the tool, C) a network of fluid channels routed within the cavity to achieve a desired mold temperature, and D) exterior mold mounting features matching machine hanger specifications.

Traditionally, one mold configuration for forming such containers includes a two-piece mold. A two-piece mold generally includes a mold holder and a cavity insert mounted within the mold holder. The cavity insert can define features A, B and C above, while feature D is defined in the mold holder. The mold holder and cavity insert are then fitted within a machine hanger. The machine hanger opens and closes the blow mold. Such two-piece mold configurations are typically used for containers having smaller diameters such as less than 95 mm (3.74 inches) for example, commonly referred to as 150 mm (5.91 inches) (referring to the inside diameter of the holder). For larger containers, a one-piece mold may be used. In a one-piece mold, all four of the above features, A, B, C and D are included in the cavity insert. Such one-piece mold configurations are used to accommodate formation of containers having diameters up to 140 mm (5.51 inches).

In either instance, it is necessary to cool the mold assembly during the mold process. In this way, cooling channels can be located within the cavity insert for delivering oil or other fluid through the cavity insert. As can be appreciated, designing and constructing such cavity inserts is complex and costly. Furthermore, because the cavity insert must be switched out when container designs change, each new mold cavity must be individually designed and formed with cooling channels routed through the structure.

[Blow Molding Molds, US Patent 8,454,343 (6/4/2013)]

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Interested!!
Bookmark this page to follow future developments!.
(RDC 6/5/2012)

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Roger D. Corneliussen
Editor
www.maropolymeronline.com

Maro Polymer Links
Tel: 610 363 9920
Fax: 610 363 9921
E-Mail: cornelrd@bee.net  

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Copyright 2013 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
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* Date of latest addition; date of first entry is 7/3/2013.