Assembly Injection Molding: New Insights Into Interface Morphology And Strength


El grupo de Materiales y Manufactura CIPP –CIPEM los invita a la siguiente charla:

Fecha: Marzo 22 de 2018
Hora: 9:30am – 10:50am
Salón: C 309

Assembly Injection Molding: New Insights Into Interface Morphology And Strength

Dr.-Ing. Ines Kuehnert / Leibniz-Institut fuer Polymerforschung Dresden e. V., Dresden, Germany.

Research Profile:

- Multi-material and assembly injection molding

- Micro injection molding

- Process induced morphology in polymer-polymer or polymer-metal-interfaces

- Development of testing methods to measure bonding strength

- Process simulation – influence of material data

Professional Experience

Position: Head of department Processing (act.) and Head of Research Group Shaping Processes and Simulation.

since 2009: Leibniz-Institute of Polymer Research Dresden, Germany.

2006-2009: University of Erlangen-Nuremberg Institute of Polymer Technology. Head of research group “Thermoplastic processing”.

1995 – 2006: Chemnitz University of Technology, Institute of Plastics and Rubber Engineering.

2002 – 2006: Chief Engineer, responsible for Education and Research management.

1995-2002: Scientific co-worker.


2005 Ph.D. “Interfaces during multi-polymer injection molding”.

1995 Diploma engineer in Mechanical Engineering/ Plastics Processing at Chemnitz University of Technology.


Part I:
Short Introduction of research at Leibniz-Institut fuer Polymerforschung Dresden e. V.

Part II:
Fundamentals about injection molding of polymer materials and assembly injection molding of polymer-polymer-bondings

The assembly injection molding technology (AIM) is more and more important as hybrid or thermal joining technology because of its cost effectiveness and process capability. In AIM, interfaces are generated by overmolding a preform, usually after it was chilled, hardened and shrinked. Considering the generation of substance-to-substance interfaces, certain questions are still unanswered, i.e. concerning the impact exerted by the material, interfacial morphology, the process parameters and the interface effects on adhesion mechanisms.
The influence of process parameters, particularly with regard to the cooling rate, on the specific interfacial morphology and strength of paired polymers will be discussed. In the experiments different semicrystalline; amorphous and filled polymers were used. Regarding the strength was determined and for the visual inspection of interfacial semicrystalline morphology polarized light microscopy was used. The second important interface during injection molding process is well known as weld line which represents two melt streams meeting during a standard injection molding process. The comparison between these two interfaces presented here will focus on substance-to-substance bonds between plastics. An overview will show the propensity to fail for several thermoplastics, in case there are interfaces in the injection molded part. The strengths will be compared for certain thermoplastics. In conclusion, new aspects about a correlation between interfacial morphology, bonding strength and injection molding parameters are addressed.

Assembly injection molding used for polymer metal hybrids
Another AIM relevant application is related to the manufacturing of polymer-metal hybrids. Nowadays, polymer-metal hybrids are covering a broad range of advanced applications, especially in the automotive or aerospace industries where high performance and lightweight components are highly demanded. Hybrid parts may offer additional functionality regarding strength, durability, impact and wear resistance without sacrificing size or weight of the full component. However, there are still challenges regarding the adhesion between dissimilar materials such metals to plastics, and especially when the hybrid component is subjected to extreme environmental. There is also a lack of research about the influence of a post-heat treatment on the durability of polymer-metal hybrids manufactured through an overmolding processing chain. In this lecture, a polyester-based powder-coat adhesive developed in the Leibniz-Institute für Polymerforschung Dresden e.V. (IPF-coat) used as adhesive promoter on metal substrates will be discussed. In the process chain a Thermoplastic Polyurethane (TPU) was overmolded on pre-coated steel substrates, and the adhesion of the polymer to the metal substrate was investigated after a heat treatment (annealing), and a subsequent hygrothermal aging at different temperature-humidity conditions. The influence of the annealing process on the adhesion and durability of the multilayered specimen will be shown; similarly, failure modes and lifetimes how they were evaluated after the hygrothermal aging. Adhesion of TPU on the steel substrate using the IPF-coat as adhesive promoter was successful due to the contribution of new physical-chemical and mechanical interactions at the polymer-coating interface, especially after annealing.