A thorough overview of the float glass manufacturing method

Today, there are three different forms of flat glass: flat pull, float, and calendaring. Float glass, which makes up more than 90% of all glass produced worldwide, serves as the foundation for all architectural glass. The float glass manufacturing method, which was developed in 1952, is the industry standard for producing high-quality glass. There are five key steps in the production of float glass:

● Ingredients

● Melting

● Forming and coating

● Annealing

● Cutting and packaging

Ingredients

The first stage of preparing the raw material for melting is the component. Sand, dolomite, limestone, soda ash, and salt cake are among the raw materials that are constantly carried by trucks or trains. These raw materials are stored in the mixing room, which is equipped with silos, hoppers, conveyor belts, chutes, dust collectors, and the required control systems to regulate raw material conveyance and batch material mixing. The raw materials are in constant motion from the moment they are delivered to the warehouse.

A long flat conveyor belt in the mixing room transports raw materials in sequence from the silos of various materials, one layer after another, to the bucket elevator and then to the weighing device to test their compound weight. These ingredients contain recycled glass shards or production line backfills. Each batch contains between 10% and 30% cullet. The dried material is mixed into the mixture after being added to the mixer. The stirred mixture is transported by conveyor belt to the kiln head warehouse for storage before being added to the melting kiln at a controlled rate by the feeder.

Melting

A typical furnace is a horizontal flame furnace with six regenerators, measuring approximately 25 meters wide and 62 meters wide, and capable of producing 500 tons per day. The melting or clarifying pool, the working poor, the regenerator, and the small furnace are the furnace's main components. As shown in image 4, it is made of special refractory materials and has a steel frame. The feeder transports the mixture to the melting pool of the melting furnace, which is heated to 1650 degrees Celsius by a natural gas spray gun.

The molten glass is stirred evenly as it flows from the melting pool through the clarification pool to the neck area. It then flows into the work section and gradually cools to around 1100 degrees, allowing it to reach the proper viscosity before entering the tin bath.

Forming and coating

The clarified liquid glass is mechanically manipulated into a glass plate according to the natural tendency of the material, which has a natural thickness of 6.88 mm. The liquid glass flows from the furnace through the flow channel area and is controlled by a flashboard, which is an adjustable door that penetrates about 0.15 mm of liquid glass. The name "float glass" comes from the fact that it floats on molten tin liquid. Glass and tin do not react and can be separated; their molecular forms repel each other, making the glass extremely smooth.

A tin tank is a container that is sealed in a nitrogen and hydrogen-controlled atmosphere. It consists of a steel support, a top cover and a bottom case, refractories, a tin and heating element, a reducing atmosphere, temperature sensors, and a computer process control system. It is approximately 8 meters wide and 60 meters long, and the production line can reach speeds of up to 25 yards per minute. With an average temperature of 800 °C, the tin bath contains nearly 200 tons of pure tin. When the glass forms a thin layer at the end of the tin bath inlet, known as a glass plate, a series of adjustable edgers on each side are activated. The operator uses a control program to set the speed of the annealing kiln and the edger. The glass plate thickness can range between 0.55 and 25 mm. The upper partition heating element is used to regulate the temperature of the glass. The temperature of the glass sheet will gradually decrease as it flows through the tin tank, making the glass flat and parallel. AcuraCoat ® pyrolytic CVD equipment can now plate reflective films, LOW E films, solar control films, photovoltaic films, and self-cleaning films. The glass is now cool enough to handle.

The glass is spread into a thin layer on the molten tin liquid and kept separate from the molten tin liquid to form a plate shape. The hanging heating element provides heat, and the speed and angle of the edger control the width and thickness of the glass.

Annealing

When the shaped glass exits the tin tank, the temperature of the glass is 600 degrees. If the glass plate is cooled in the atmosphere, the surface of the glass will cool faster than the interior, resulting in severe surface compression and harmful internal stress on the glass plate.

The heating of the glass before and after forming is also an internal stress formation process. As a result, annealing is required to reduce the temperature of the glass to the ambient temperature. The annealing is done in an annealing kiln with a temperature gradient that is about 6 meters wide and 120 meters long. The annealing kiln has an electrically controlled heating element and a fan to keep the lateral temperature of the glass sheet constant.

In a nutshell, the annealing process carefully cools the glass to room temperature without causing temporary stress or stress.

Cutting and packaging

A roller conveyor connected to the annealing kiln drive system transports the cooled glass plates to the cutting zone. The glass is inspected online for flaws and then cut with a diamond cutting wheel to remove the glass's edges (the edge material is recycled into a cullet). It is then cut to the size required by the customer. The surface of the glass is sprinkled with a powder medium to allow stacking and storage of glass sheets without sticking or scratching. The flawless glass panels are then manually or automatically stacked and transferred to the warehouse for storage or shipment to the customer. Click here for Accessories For Glass Cutting.