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An Investigation of the Native and Manipulated Effects of Shear Imbalanced Melt Flows during Molding Processes.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	An Investigation of the Native and Manipulated Effects of Shear Imbalanced Melt Flows during Molding Processes./
Author:	Li, Qi.
Description:	1 online resource (271 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 78-07(E), Section: B.
Contained By:	Dissertation Abstracts International78-07B(E).
Subject:	Mechanical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9781369637373

An Investigation of the Native and Manipulated Effects of Shear Imbalanced Melt Flows during Molding Processes.
Li, Qi.

An Investigation of the Native and Manipulated Effects of Shear Imbalanced Melt Flows during Molding Processes. - 1 online resource (271 pages)

Source: Dissertation Abstracts International, Volume: 78-07(E), Section: B.

Thesis (Ph.D.)

Includes bibliographical references

Runner-based shear imbalances is a common feature in injection molding of polymers. Its effect on the melt flow is a main concern, causing problems even in cases where the mold cavities are naturally balanced and the geometry is traditionally defined. Melt rotation technology has been applied to address this issue, as well as that of shrinkage and warpage.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781369637373Subjects--Topical Terms:

557493
Mechanical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

An Investigation of the Native and Manipulated Effects of Shear Imbalanced Melt Flows during Molding Processes.
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100 1 $a Li, Qi. $3 1022336
245 1 3 $a An Investigation of the Native and Manipulated Effects of Shear Imbalanced Melt Flows during Molding Processes.
264 0 $c 2017
300 $a 1 online resource (271 pages)
336 $a text $b txt $2 rdacontent
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500 $a Source: Dissertation Abstracts International, Volume: 78-07(E), Section: B.
500 $a Adviser: John P. Coulter.
502 $a Thesis (Ph.D.) $c Lehigh University $d 2017.
504 $a Includes bibliographical references
520 $a Runner-based shear imbalances is a common feature in injection molding of polymers. Its effect on the melt flow is a main concern, causing problems even in cases where the mold cavities are naturally balanced and the geometry is traditionally defined. Melt rotation technology has been applied to address this issue, as well as that of shrinkage and warpage.
520 $a In the present study, this technology is taken several steps further with the goal of exploring and solving product quality variations that is attributed to the imbalanced polymer melt flow problem. Molding trials were conducted with and without melt rotation using several types of polymers, and the resultant effects on the physical, thermal, and mechanical properties of the molded products were explored. The study found that important product quality parameters such as crystallinity and tensile modulus vary significantly throughout conventionally molded products, and that these can be dramatically altered by implementation of the melt rotation technology. For semi-crystalline materials, specimens taken from product regions associated with higher melt flow shear levels exhibited higher crystallinity levels as well as higher tensile moduli due to the localized shear rate variation.
520 $a This work also includes visual analysis of how shearing of the polymer through the runner system affects mold filling in real-time. Multi-cavity molding is widely used to increase manufacturing efficiency by primarily reducing time and cost. It is mainly generally accepted that the optimal runner design is one that is geometrically balanced. However, is now also understood that imbalances are also due to the shearing of the polymer melt as it is pushed through the runner system. To gain a deeper understanding on how this occurs, a custom-built mold with transparent mold inserts and runner system was utilized. Cavity filling of polymers into different cavity designs was captured using a high-speed camera. Analysis of this visual data would provide aid in finding methods to mitigate the non-uniform behavior of molten polymers undergoing shear-thinning. Molding trials were implemented and experimental results have been found to support the effectiveness of the melt rotation technology.
520 $a The results in this work also show the potential of adopting the technology for a broader range of applications that require a homogeneous polymer melt flow for ensuring efficient manufacturing and desired quality products.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Mechanical engineering. $3 557493
655 7 $a Electronic books. $2 local $3 554714
690 $a 0548
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a Lehigh University. $b Mechanical Engineering. $3 845623
773 0 $t Dissertation Abstracts International $g 78-07B(E).
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10251571 $z click for full text (PQDT)