Study on the optical quality and strength of glass edges after the grinding and polishing process

Paulina Bukieda,Jens Meiberg,Katharina Lohr,Bernhard Weller

doi:10.1007/s40940-020-00121-x

Paulina Bukieda, Jens Meiberg + Show 2 more

Open Access

https://doi.org/10.1007/s40940-020-00121-x

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Abstract

Glass edges result from cutting glass sheets and a further optional finishing. The mechanical interference into the brittle material glass causes flaws and cracks at the edge surface. Those defects have an influence on the strength of the whole glazing. Within the scope of a research project at the Institute of Building Construction from the Technische Universität Dresden, the grinding and polishing process is examined in terms of characteristic visible effects on the glass edge and the edge strength. Thereby a special focus of the research project is the impact of various polishing cup wheels for the chamfer surface of annealed glass. The article presents some basics about the processing steps of glass edges surfaces, introduces the considered grinding and polishing cup wheels and gives an overview of the performed experimental examinations. A microscopic analysis enables a characterisation of typical defects at the surfaces. Furthermore, four-point bending tests are performed to determine the bending tensile stresses at failure. The combination of both methods enables an analysis of the fracture-causing defect before destruction and a correlation between the optical surface quality and the bending tensile stresses. Additionally, the microscopy could be used to support the adjustment of a grinding machine and control reproducible edge qualities. The evaluation shows that a special development of polishing cup wheels for the chamfer can improve the surface quality and consequently increases the edge strength.

Highlights

1.1 Consideration of glass edge strength in the designThe mechanical and thermal loads in window and facade constructions are growing with modern architectural demands and firm requirements for building physics
That reduction considers the high scattering of the edge strength due to the processing and represents a minimum level of the glass edge strength
Along with that, increasing bending tensile stresses were determined, what further led to the determination of a higher glass edge strength

Summary

Introduction

1.1 Consideration of glass edge strength in the designThe mechanical and thermal loads in window and facade constructions are growing with modern architectural demands and firm requirements for building physics. 1.1 Consideration of glass edge strength in the design. With increasing glass formats and complex glass structures, the superposition of mechanical and especially thermal loads can cause critical stresses in the edge areas. That reduction considers the high scattering of the edge strength due to the processing and represents a minimum level of the glass edge strength. The reduced resistance of the edge strength of annealed glass and the lack of adaptable load scenarios on glass edges lead to insecurities. To ensure a certain level of safety in the design of glass structures and damage-free glazing, a further in-depth examination of the glass edges is necessary. Planners often use tempered glass, which shows a higher edge strength. A safety design approach and a production of annealed glass with an acceptable edge strength and a low scattering are necessary

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