Untersuchungen zur Bindenahtfestigkeit von technischen Bauteilen aus kurzfaserverstärkten Thermoplas

FKM 2001
Booklet No. 265
Project No. 232

Abstract:

Fiber-filled thermoplastic injection molded parts exhibit anisotropy of properties due to the fiber orientation induced by processing. When filling the cavity, flow-related disturbances can cause melt fronts to meet, resulting in so-called weld lines. A distinction is made here between weld lines that are formed when the flow fronts meet head-on with immediate standstill and those that are formed when the meeting melt fronts continue to flow in parallel. In contrast to unreinforced thermoplastics, fiber-reinforced thermoplastics also have fibers that are oriented along a weld line. As a result, components under load perpendicular to the weld line hardly achieve the strength of the unreinforced matrix. The aim of the research project is therefore to investigate the relationships between geometry, processing, structure and properties in more detail and to check the predictability using commercial mold filling simulation software on the basis of experimental studies. The main results of the research project are that a distinction must be made between symmetrical components and more complex geometries when predicting weld line position and length using mold filling simulation. For symmetrical geometries, the prediction is unsatisfactory and can only be corrected by modifications. For more complex geometries and a corresponding casting technique - example of a practical component - the prediction largely corresponds to the experimental mold filling study and the microscopic investigations of the fiber orientation. Here, the flow through the weld line region has partially led to an elimination of the typical weld line orientation. These findings allow the product and tool developer to make conscious use of the mold filling calculations. Furthermore, various possibilities for generating a flow through the weld line can be derived. The objective of the research project has been achieved. Scope of report:
30 p., 27 Fig., 1 Tab., 24 Lit Start of work:
01.02.1999 End of work:
31.03.2001 Funding body:
BMWi, AiF-No.: 11939 B Research unit:
Professorship for Plastics Processing Technology, Chemnitz University of Technology 09107 Chemnitz Prof. Dr.-lng. G. Mennig Author:
Prof. Dr.-lng. habil. F. Meyer Ms. Dipl.-lng. I. Kühnert Chairman of the working group:
Dr.-lng. A. Singer, Sachsenring AG Chairman of the advisory board:
Dr.-lng. h. c. J. Rabe, Sachsenring AG