Controlling cellular structure in thermoplastic foam injection molding – influence of processing and mold technologies

Tromm, Mike

dc.date.accessioned	2021-02-08T08:58:50Z
dc.date.available	2021-02-08T08:58:50Z
dc.date.issued	2020
dc.identifier	doi:10.17170/kobra-202008261646
dc.identifier.uri	http://hdl.handle.net/123456789/12466
dc.description	Zugleich: Dissertation, Universität Kassel, 2020	ger
dc.language.iso	eng	eng
dc.publisher	kassel university press
dc.rights	Namensnennung - Weitergabe unter gleichen Bedingungen 4.0 International	*
dc.rights.uri	http://creativecommons.org/licenses/by-sa/4.0/	*
dc.subject	foam injection molding	eng
dc.subject	core-back	eng
dc.subject	mold-opening	eng
dc.subject	cellular plastics	eng
dc.subject	structure development	eng
dc.subject	process-structure relationship	eng
dc.subject	lightweight construction	eng
dc.subject.ddc	600
dc.subject.ddc	660
dc.title	Controlling cellular structure in thermoplastic foam injection molding – influence of processing and mold technologies	eng
dc.type	Buch
dcterms.abstract	Foam injection molding is a processing technology to produce foamed plastic parts in serials production, attaining an increasing interest and use in industry. However, the applications are limited due to insufficient knowledge of processing and mechanical properties, limited use of light-weight potential as well restricted surface qualities. All these drawbacks are associated with the cellular structure. The structure characteristics like skin layer thickness, cell size, density and uniformity are developed during procedure. Thus, controlling the cell formation process is the key to work against the restrictions and optimize mechanical properties. In conventional or low-pressure foam injection molding procedure, mold filling and foaming occur simultaneously. The cellular characteristics can only be controlled in a very limited range and are often non-uniform by flow length and cross-section, not allowing a precise prediction of the mechanical performance. These limitations can be counteracted by high-pressure foam injection molding with volume-expandable molds. This special process variant may decouple filling and foaming phase and allow an active control of cellular characteristics. Cell formation mechanism may actively be shifted from cell growth to nucleation. Thus, finer-celled, homogeneous, less flowpath dependent structures with density reductions > 50 % can be achieved, and the mechanical properties can actively be influenced. This potential is often unknown due to insufficient knowledge about the process parameters and its effects on structure formation. While the conventional or low-pressure procedure has been asserted and is used in industrial applications, high-pressure procedure with volumeexpandable molds is often unknown or used in a very limited range. This thesis deals with formation of cellular structure in thermoplastic foam injection molding process. The work focusses on influences by processing and mold technologies. High-pressure procedure in combination with volume-expandable molds – mold opening or core-back - is in focus. As a new process variant, the local core-back procedure (local mold volume expansion) is introduced, enabling a local customization of foam structures. The differences in procedures and the influence of additional process parameters are worked out. Here, especially the role of packing pressure as a key factor for structure development is discussed. To get more information on boundary conditions inside the mold during procedure and make the process more transparent, numerical simulation has been used and visualization Abstract molding trials were conducted to monitor the cell development inside the mold during processing. Furthermore, a new mold, i.a. allowing an active control of pressure drop rate was built and used. To analyze the structure and quantify the structural parameters, besides light microscopy and SEM, also x-ray tomography (μCT) was used to allow a three-dimensional characterization of structures.	eng
dcterms.accessRights	open access
dcterms.creator	Tromm, Mike
dcterms.dateAccepted	2020-06-25
dcterms.extent	IX, 233 Seiten
dcterms.isPartOf	Schriftenreihe des Instituts für Werkstofftechnik / Kunststofftechnik ;; Band 11	ger
dc.contributor.corporatename	Kassel, Universität Kassel, Fachbereich Maschinenbau	ger
dc.contributor.referee	Heim, Hans-Peter (Prof. Dr.)
dc.contributor.referee	Steinbichler, Georg (Prof. Dr.)
dc.publisher.place	Kassel
dc.relation.isbn	978-3-7376-0887-9
dc.subject.swd	Spritzgießen	ger
dc.subject.swd	Schaumkunststoff	ger
dc.subject.swd	Mechanische Eigenschaft	ger
dc.subject.swd	Prozessentwicklung <Technik>	ger
dc.subject.swd	Werkzeug	ger
dc.subject.swd	Leichtbau	ger
dc.subject.swd	Chemische Struktur	ger
dc.type.version	publishedVersion
dcterms.source.series	Schriftenreihe des Instituts für Werkstofftechnik / Kunststofftechnik	ger
dcterms.source.volume	Band 11	ger
kup.iskup	true
kup.price	39,00
kup.series	Schriftenreihe des Instituts für Werkstofftechnik / Kunststofftechnik
kup.subject	Naturwissenschaft, Technik, Informatik, Medizin
kup.typ	Dissertation
kup.institution	FB 15 / Maschinenbau
kup.binding	Softcover
kup.size	DIN A5