Tribological wear analysis and numerical lifetime prediction of glassy carbon tools in fused silica molding

• Published in: Wear Vol. 364-365; pp. 144 - 153
• Main Authors: Dukwen, Julia, Friedrichs, Marcel, Liu, Gang, Tang, Minjie, Dambon, Olaf, Klocke, Fritz
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2016
• Subjects: AFM; Contact mechanics; Finite element modeling; Glassy carbon; Precision Glass Molding; Sliding wear; AFM; Finite element modeling; Sliding wear; Precision Glass Molding; Glassy carbon; Contact mechanics
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2016.07.011

Precision Glass Molding (PGM) is currently the standard manufacturing process for medium-lot-size fabrication of complex shaped, high-quality lenses. During each molding cycle in PGM, the molding tools experience thermal and mechanical loads. Degradation mechanisms caused by these loads limit the molding tool life. Therefore, acquiring a deeper knowledge of the fundamental degradation mechanisms of molding tool surfaces is of high-interest. In this work, the tribological wear mechanisms of the surfaces of glassy carbon tools used for fused silica molding were investigated. Both an experimental study and a finite element method (FEM) simulation are presented, and their results were correlated. In the experimental study, the progressive wear process on glassy carbons surfaces was investigated using scanning electron microscopy (SEM). In addition, atomic force microscope (AFM) measurements of the sizes of surface defects such as notches were analyzed. Experimental results were compared with a FEM simulation of the tensile stresses and sliding velocity that arise during each fused silica molding cycle. Using this approach, the dimensions of wear can be calculated after any given number of molding cycles and the lifetime of the molding tools can be predicted. •Tribological wear restricts the lifetime of glassy carbon molding tools.•The contact pressure and the sliding velocity were determined by FEM simulation.•A numerical procedure was developed for the calculation of the wear coefficient.•The molding tool lifetime is quantitative predictable.•The developed methods can be transferred to other molding processes.