Thermal Embossing Method for Glass Recycling

Abstract

Over the past years the target for waste recovery/ recycling has significantly increased in Romania, in according with the EU Directives. Nowadays, the competitive contexts of the current market lead the manufacturers to obtain novel and custom-made products using new technologies and quality raw materials. Such resources can be consisting of low-cost waste/by-products and in the processes of converting them into value-added products. On the other hand, the necessity for recycling waste is important under the strict European legislation. Regarding glass, the key sources of waste are container/ packaging glass, flat glass, electric and electronic equipments, domestic glass, E-glass, etc. According with source, waste glass can be: pre-and post-consumer waste glass. Now many recycling processes have been studied, developed and applied in industry. The major challenge is represented by creating of innovative and sustainable technologies and making it suitable. But recycling of glass is technologically more complicated than other waste (for example: paper). In case of glass, the most sustainable route is to use it for re-melting processes and obtaining a new glass. Glass is 100% recyclable but not all waste/cullet can be used for the manufacturing of any type of glass, due different chemical composition and the prohibitive shipping costs from collection points to glass factory. In this study, authors paid attention to the recycling process of soda-lime glass (post-industrial flat glass) and proposed the thermal embossing technique of glass, using glass slumping process, in order to obtain decorative products with aesthetic impact and functional role. An input image is prepared by applying different enhancement techniques, adjusting contrast, transferring into grayscale image in 256 shades of gray. The result image is transferred in Computer Aided Manufacture (CAM) software to refine the surface geometries and to obtain with rapid tooling the mould for glass. The method used for tooling fabrication consists of machining a block of suitable material with a Computer Numerical Controlled (CNC) machine which is known as a subtractive method. The next stage consists in applying of the heat treatment, using an electrical furnace. The major advantages of the embossing method for converting waste glass in value-added products is represented in the fact of use reduced energy comparing with the classic route of re-melting, possibility of obtaining bespoke products, ready to use in architectural and decorative fields. In addition, environmental benefits that results from processing waste glass are the reducing the raw materials (virgin) and the CO2 emissions.