Table of Contents
Journal of Polymers
Volume 2017 (2017), Article ID 8241859, 11 pages
Research Article

Variation of the Pole Length in Pole-Oriented Bonded Rings due to the Location and Number of Injection Points

Institute of Polymer Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Am Weichselgarten 9, 91058 Erlangen, Germany

Correspondence should be addressed to Katharina H. Kurth

Received 10 November 2016; Revised 12 January 2017; Accepted 17 January 2017; Published 15 February 2017

Academic Editor: Zhong-Ming Li

Copyright © 2017 Katharina H. Kurth and Dietmar Drummer. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Polymer bonded magnets are compounds consisting of a polymer matrix with embedded hard magnetic filler particles. These materials are mainly used in applications in actor or sensor technology. One example is the application as multipolar encoder wheel in magnetic sensors. Depending on the application different requirements have to be fulfilled, such as a high pole length accuracy and repeatability. This investigation deals with the production of multipolar rings in the injection molding process for sensor applications and influences of the design of the gating system on the pole length accuracy. It is shown that the number of injection points and developing weld lines, as well as the positioning of the injection points, has a major influence on the magnetization characteristics of the molded rings. In general, a positioning of injection points and weld lines in the pole pitch and higher number of injection points lead to rings with a high reproduction accuracy of the pole length of the mold.