Untersuchungen zur Vorhersagbarkeit der Reibung zwischen Polymeren und beschichteten sowie unbeschichteten Werkzeugoberflächen durch Benetzungsparameter

Translated title of the contribution: Studies on the predictability of friction between polymers and coated and uncoated tool surfaces by wetting parameter

Clemens Steffel

    Research output: ThesisMaster's Thesis

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    Abstract

    The aim of this thesis was to qualitatively predict demolding forces in the injection molding process by determining wetting parameters of the materials involved. By using test liquids Ethylene Carbonate and Bromonaphtaline the wetting behaviour was studied for PA6, PC and typical tool steels and tool coatings in a temperature range from 40°C to 200°C. The polar and the disperse fractions of the surface energies, and the interfacial tension gamma12 of each combination of polymer and (coated) steel surface was calculated by using OWRK method. An inverse relationship between friction while demolding and calculated interfacial tension gamma12 was expected. At a contact temperature of 90°C MoN and PA6 as mating partners show the greatest friction, which was predicted by the lowest interfacial tension gamma12. Steel grade M268, CrN and CrC/a-C:H succeed, the latter with the lowest friction to PA6. The M333 IP and M268 VMR steels do not behave as expected due to significant higher roughness. As predicted, CrC/a-C:H and PC as mating partners show the lowest static coefficient of friction μ0, followed by CrN, M268 VMR and M333 IP, respectively. The second lowest μ0 of MoN is unexpected. Moreover, friction of PC on M303 is much lower than anticipated. Thus, the wetting parameter interfacial tension gamma12 qualitatively predicts the friction behaviour of some combinations of polymer and (coated) steel surface very well. Nevertheless, this is not sufficienter to develop future steels and coatings without friction tests. One reason for this is, that small roughness differences on mirror-finished mold surfaces do not affect the calculated interfacial tension, but they have a strong effect on coefficients of friction.
    Translated title of the contributionStudies on the predictability of friction between polymers and coated and uncoated tool surfaces by wetting parameter
    Original languageGerman
    QualificationDipl.-Ing.
    Supervisors/Advisors
    • Berger, Gerald, Co-Supervisor (internal)
    • Friesenbichler, Walter, Supervisor (internal)
    Award date19 Dec 2014
    Publication statusPublished - 2014

    Bibliographical note

    embargoed until 14-11-2019

    Keywords

    • Prediction of demolding forces
    • wetting behaviour
    • contact angle
    • interfacial tension
    • friction tests
    • injection molding
    • temperature dependancy
    • plastics

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