Glasherstellung - Das Floatverfahren (Saint-Gobain)

Bundesverband Flachglas e. V.

13 Jul 201510:37

Summary

TLDRThe script delves into the intricate process of glass manufacturing, highlighting its ubiquitous yet invisible nature in modern applications. Key ingredients like quartz sand, soda, and lime are crucial, with dolomite added for building and automotive glass. The float process is central, detailing the mixing, melting, and slow cooling stages. It emphasizes the float plant's role in producing high-quality, cost-effective glass, showcasing the importance of the float bath and the use of tin to create a smooth, planar glass surface. The script concludes by noting the adaptability of float glass for various applications, such as thermal insulation and soundproofing.

Takeaways

🏭 Glass is a material with a wide range of applications and is produced through an intricate process.
💠 The main raw materials for glass production are quartz sand, soda, and lime, with dolomite added for building and vehicle glass.
🔥 The raw materials are mixed and melted at temperatures between 800 to 900°C, with the melting process being observable only through special glasses.
🌡 The melting process involves three areas: melting of the mixture, refining at up to 1560°C, and cooling to around 1100°C.
💧 The float process is used for industrial glass production, where the glass is formed by flowing over a bed of molten tin.
🔄 The float process involves a non-visible transition area between the melting pot and the float bath, facilitated by a lip stone.
🌌 The principle of glass spreading evenly over the tin bath is similar to how two immiscible liquids like chloroform and glycerin form a smooth separation layer.
📏 The thickness of the glass is controlled by the speed at which the molten glass is drawn over the tin bath, managed by top rollers.
🌡️ The cooling process in the float bath is carefully controlled to prevent stress in the glass, with the temperature dropping from 1100°C to 600°C.
🛠️ The flat glass is then slowly cooled in a roller cooler to room temperature, ensuring a stress-free cooling process over a length of 160 meters.
♻️ Defective areas are identified and marked for automatic sorting out, and the glass is cut to size for transportation and potential recycling.

Q & A

What are the main raw materials used in glass manufacturing?
-The main raw materials for glass manufacturing are quartz sand, soda, and lime. For building and vehicle glass, dolomite is also added as an additional raw material.
What is the float process in glass manufacturing?
-The float process is an industrial method used to produce flat glass of a high quality standard. It involves floating molten glass on a bed of molten tin to create a flat, parallel surface.
Why is dolomite added to the raw materials for building and vehicle glass?
-Dolomite is added to the raw materials for building and vehicle glass to improve the chemical composition and physical properties of the final product.
What causes the brownish-red color of the glass mixture?
-The brownish-red color of the glass mixture is due to small amounts of iron oxide added to the raw materials.
How is the glass mixture melted and at what temperature?
-The glass mixture is melted in a melting furnace at temperatures between 800 and 900°C. The melting process begins when the quartz sand melts at around 1450°C.
What is the purpose of the three different areas in the melting furnace?
-The melting furnace has three areas: the first for melting the mixture, the second for refining at up to 1560°C to homogenize the glass melt and remove gas bubbles and streaks, and the third for cooling the melt to about 1100°C.
How does the float bath work in the glass manufacturing process?
-The float bath works by utilizing the different densities of tin and glass. The molten glass spreads evenly over the entire tin bath, floating on the surface due to the density difference.
Why is tin used in the float bath?
-Tin is used in the float bath because it remains liquid at 600°C and does not evaporate even at 1100°C, which is necessary for the glass to cool and solidify evenly.
How is the thickness of the glass controlled during the float process?
-The thickness of the glass is controlled by the speed at which the molten glass is drawn across the tin bath and managed with the help of top rollers.
What happens to the glass after it leaves the float bath?
-After leaving the float bath, the glass is slowly cooled in a roller cooler from 600°C to 200°C over a length of 160 meters to ensure stress-free cooling.
How is the quality of the glass checked after it is formed?
-The quality of the glass is checked for inclusions, bubbles, and streaks. Defective areas are marked and later automatically sorted out for potential recycling back into the melting process.

Outlines

00:00

🔍 The Complex Process of Glass Production

This paragraph delves into the intricate process of manufacturing glass, a material with a multitude of applications yet seemingly simple in appearance. The primary ingredients for glass production are quartz sand, soda, and lime, with dolomite added for building and automotive glass. The process involves five main steps: mixing the raw materials, melting the mixture, shaping the molten glass, slow cooling, and cutting. The industrial production of glass for construction and vehicles must meet high-quality standards while being cost-effective, a requirement met by the float process. The float plant is preceded by a batching house with storage for raw materials, ensuring quality. The materials are transported to mixers where the mixture is created, including recycled glass cullet from the float glass production, which contributes to the brownish color due to iron oxide additives. The mixture is then fed into a melting furnace, where approximately 700 tons of glass mass are melted per day in a continuous process at temperatures between 800 to 900°C. The melting process is observed through refractory glass, and gas burners provide the necessary heat. The melting furnace has three sections: melting, fining, and cooling, with the glass mass constantly moving due to temperature differences. The fining process at around 1560°C homogenizes the glass, removing gas bubbles and impurities, and the cooling section gradually reduces the temperature to prepare the glass for shaping.

05:02

🏭 The Float Glass Manufacturing Technique

The second paragraph explains the float glass manufacturing technique, which is used to create flat glass with a smooth and even surface. The process begins with the molten glass flowing over a 'Lippenstone' onto a bed of molten tin in a float bath, taking advantage of the different densities of tin and glass. This creates a smooth separation layer, similar to how two immiscible liquids like chloroform and glycerin form a distinct layer. The glass spreads evenly over the tin, and its thickness is controlled by the speed at which the glass is drawn across the tin and adjusted by top rollers. The hot tin, initially at 1100°C, ensures a flat underside of the viscous, glowing glass ribbon. The glass then cools down to around 600°C, with the temperature of the tin bath being stepped down and electric heaters on the glass surface ensuring an even temperature drop. The use of tin is crucial as it remains fluid at 600°C and does not evaporate even at 1100°C. The float process must occur in a protective gas atmosphere to prevent oxidation of the tin. By the end of the float bath, the glass ribbon is form-stable enough to be lifted from the tin bath, marking the completion of the forming process. The green glass ribbon is then guided into the roller coolers, where it is slowly and electronically controlled from 600° to 200°C over a 160-meter length to ensure stress-free cooling. The glass ribbon cools down to room temperature in the open roller track. Quality control checks for inclusions, bubbles, and streaks, marking defective areas for later automatic sorting. The glass is then cut to a transportable glass sheet size, with only these cut and sorted glass sheets being suitable for recycling back into the float plant. The outcome of the float process is flat glass with surfaces that are even and parallel, also referred to as mirror glass quality.

10:06

🌐 Applications and Further Processing of Float Glass

The final paragraph discusses the applications and further processing of float glass to meet modern demands for thermal insulation, solar protection, and sound insulation. Float glass serves as the starting product for a variety of applications and undergoes numerous additional processing steps to adapt to specific use cases. It is enhanced and transformed through various techniques to cater to the specialized needs of different industries, showcasing the versatility and importance of float glass in contemporary construction and automotive sectors.

Mindmap

Keywords

💡Glass

Glass is an amorphous, inorganic, non-metallic solid that is produced by heating a mixture of raw materials to a high temperature, which then cools to form a rigid, often transparent, material. In the context of the video, glass is the primary material being produced, with a focus on its manufacturing process and applications in construction and automotive industries.

💡Raw materials

Raw materials refer to the basic substances used to produce goods, which in the case of glass, include quartz sand, soda, and lime. For building and vehicle glass, dolomite is also added. These substances are essential for the glass-making process and are mixed together before melting.

💡Float process

The float process is a method used in the production of flat glass. It involves floating molten glass on a bed of molten tin, which allows the glass to spread out into a thin, even sheet. This process is highlighted in the video as the primary method for creating high-quality, flat glass that meets the standards required for construction and automotive applications.

💡Melting

Melting is the process of applying heat to turn solid raw materials into a liquid state. In the video, the raw materials for glass are melted at temperatures of around 800 to 900°C to create a molten glass mixture. This is a crucial step in the glassmaking process, as it allows the materials to be combined and shaped.

💡Homogenization

Homogenization in the context of glass production refers to the process of making the glass melt uniform in composition and free from gas bubbles and striations. This is achieved during the 'fining' stage in the melting process, where the molten glass is heated to around 1560°C to ensure it is smooth and free of impurities.

💡Annealing

Annealing is the process of slowly cooling and controlled heating of glass to relieve internal stresses and make it more stable. In the video, the glass is cooled from 1100°C to around 600°C in a controlled manner to ensure it is stress-free and of high quality.

💡Roller cooling

Roller cooling is a part of the glass manufacturing process where the glass is cooled down to room temperature in a controlled environment. The video mentions that the glass is cooled from 600°C to 200°C in a roller cooler, which is essential for achieving a stress-free glass product.

💡Quality control

Quality control is the process of ensuring that the glass produced meets the required standards for defects such as inclusions, bubbles, and striations. The video describes how the glass is inspected for these defects, and any faulty areas are marked for automatic sorting and potential recycling.

💡Recycling

Recycling in the context of the video refers to the potential for reusing glass products that have been processed or are defective. The script mentions that there are developments in processes that could allow for the recycling of flat glass products, contributing to sustainability in the glass industry.

💡Tempering

Tempering is a heat treatment process that strengthens the glass by increasing its surface compression. Although not explicitly mentioned in the script, the process of cooling the glass to room temperature in a controlled manner is part of the tempering process, which is essential for creating strong, safety glass used in various applications.

💡Mirror quality

Mirror quality refers to the smoothness and flatness of the glass surface. The video mentions that the float glass produced has surfaces that are even and parallel, which is indicative of high-quality glass that can be used for applications like mirrors or where a high level of clarity is required.

Highlights

Glass is a material with a wide range of applications, yet it is almost invisible at first glance.

The production of glass is a complex process despite its seemingly simple nature.

Key raw materials for glass production include quartz sand, soda, and lime.

Dolomite is also used as a raw material for building and vehicle glass.

The glass manufacturing process involves five main steps: mixing, melting, forming, annealing, and cutting.

The float process is used for the industrial production of building and vehicle glass, ensuring high quality and economic efficiency.

Raw materials are stored in silos and are mixed in a batching house before being sent to the mixers.

The red-brown color of the mixture is due to small amounts of iron oxide.

The melting process begins at around 700 tons of glass mass per day, requiring approximately 2000 tons of molten glass in the melting tank.

The melting process in the melting tank is observed through sight glasses and is fueled by gas burners.

Lime and soda act as fluxing agents in the mixture, reducing the melting point of the quartz sand.

The melting tank has three distinct areas: melting, fining, and cooling.

The glass melt is homogenized during the fining process, becoming free of gas bubbles and striations.

The glass melt flows onto a tin bath in the float process, where it takes advantage of the different densities of tin and glass.

The thickness of the glass is controlled by the speed at which the molten glass is drawn across the tin bath.

The glass is cooled in a controlled manner from 1100° C to 600° C in the float bath.

The float process must occur in a protective gas atmosphere to prevent oxidation of the tin.

The flat glass ribbon is already form-stable by the end of the float bath, ready to be lifted from the tin bath.

The glass ribbon is cooled slowly and electronically controlled in the roller coolers from 600° to 200° C.

Quality control checks for inclusions, bubbles, and striations, with defective areas marked for automatic sorting.

The glass is cut to a transportable size, with only sorted and defect-free glass suitable for recycling.

Float glass is the starting product for a variety of applications, adapted to specific uses through further processing steps.

The float process results in flat glass with even surfaces, also known as mirror glass quality.