We may not notice in life, in fact, there is always glass around. For example, the glass Windows of the home, the windshield of the car, the external walls of the office building, vases and so on. You might suddenly realize: Oh! There really is glass everywhere. But you probably don't wonder, how did the glass get there?
Glass is an ancient and mysterious material. It is believed that the first glass container was created in 1500 BC. Glass is brittle but durable. Many fragments of glass can be found in early cultural sites. Because glass itself can be made into all kinds of shapes, and it's sterile. Therefore, it is also commonly used as a container, such as cups and test tubes. The cost is relatively low, very suitable for mass production. With the continuous development of science and technology, the functions of glass are gradually diversified. The manufacturing process of glass from raw material to finished product is described in detail below.
The main component of glass
The main component of glass is silicon dioxide (SiO2), which is the basic material for making glass. In addition, other materials are required to be added. In this way, the characteristics of the glass and the manufacturing process are adjusted. These raw materials are:
Soda ash (Na₂CO₃) : This material can reduce the melting point of silica sand and facilitate high-temperature processing.
Limestone (CaCO₃) : Because glass may dissolve in water when melted, adding limestone makes the glass insoluble. It also increases the hardness and durability of the glass. To make the commonly used hard glass.
Alumina (Al₂O₃) : Enhances the chemical stability of the glass.
Magnesium oxide (MgO) : can improve the strength and heat resistance of glass.
Other additives: add iron oxide, zinc oxide, etc., as needed to give the glass a specific color or characteristics.
Transparency to visible light is the most important feature of glass. Ordinary glass is not transparent to ultraviolet light because it is made with sodium carbonate. If ultraviolet light is to penetrate, glass must be made of pure silica. This kind of glass has increased in cost and is generally called quartz glass.
Common glass often has other ingredients added to it. For example, we see the dazzling crystal glass in the hotel or KTV. This is because lead is added to it, which can increase the refraction coefficient of the glass, so the refraction is very blinding. The kind of glass used to make optical lenses is laced with thorium oxide, which also dramatically increases the refractive index. If cerium is added to glass, it absorbs ultraviolet light. If you want the glass to have the function of absorbing infrared rays, you can add iron. This kind of insulating glass is inside the projector.
Adding various metals or metal oxides to the glass can change the color of the glass. For example, a small amount of manganese can change the light green color of the glass caused by iron, and a little more manganese can create a lavender glass. If the iron content in the glass is reduced, it can also make the light green glass itself into a basically colorless state. Adding a small amount of cobalt can also create bluish glass. Copper oxides create turquoise glass. Copper creates a deep red, opaque glass that looks like ruby. So the color of the glass can be controlled, and many additives can be done. Including changing the temperature of the glass can actually do this, but the chemistry of this is also quite complex and needs to be studied.
Mixing and melting
Mixing of raw materials: Raw materials first need to be weighed in specific grams and mixed. This process requires precise and specialized equipment. You have to make sure that the materials are evenly mixed. The mixed raw materials are called "glass ingredients".
Melting: the mixed glass ingredients are sent into the glass melting kiln. The furnace temperature is very high, usually around 1700°. At high temperatures, the glass ingredients undergo some chemical reactions and melt into molten glass. This process is a central step in glass manufacturing. In the process to maintain a constant high temperature and appropriate melting time. This can ensure the uniformity and purity of the glass.
shaping
After the molten glass is homogenized in the melting kiln, it enters the forming process. According to the shape and use of the final product, it can be divided into the following types:
Float glass: Float glass is the main manufacturing method for modern architectural and automotive glass. It was mentioned in the previous article. After the molten glass flows out of the furnace, it flows through a flow trough into a float tank containing molten tin. The liquid glass unfolds on the surface of the liquid tin, forming a smooth glass band. As the strip slowly moves and cools, it gradually hardens. The result is a flat glass with a uniform thickness and smooth surface.
Blown glass: Blown glass is mainly used for hollow products such as glass bottles and lampshades. During the blowing process, molten glass is sucked into a blow pipe. Air is then blown into the glass through the pipe, so that the glass can expand and open, and finally take shape. Blowing technology now also has an automated set of processes, and some production areas also choose manual operation.
Rolled glass: After passing between two rollers, the molten glass can be pressed into a glass sheet with a pattern. Because there are various patterns on the roller, glass products with different patterns can be pressed according to customer needs. Rolled glass is generally used to make decorative glass with decorative patterns. Most of them are used for decoration in buildings.
Drawn glass: Drawn glass can be used to make glass fibers. Molten glass can pass through a small hole and be drawn into thin glass fibers. Then we further process these glass fibers into glass cloth, glass felt and other materials. Can be used in building insulation, electronic appliances and other fields.
anneal
After the glass is formed, it also needs to undergo an annealing process to eliminate internal stress. It can enhance the mechanical strength and stability of glass. Do you know what annealing is? Annealing is the process of keeping glass at a holding temperature for a period of time and then slowly cooling it. In this process, the stress inside the glass can be released evenly. This prevents its spontaneous rupture or deformation during use.
Machining and surface treatment
Cutting and polishing: Annealed glass is cut, polished and polished for different purposes. Cutting is to cut large pieces of glass to a certain size according to customer requirements. This process is done with professional props. Generally used is a diamond cutter. Grinding and polishing generally smooth the edges of the glass. This prevents the sharp edges from causing harm to the human body.
Surface treatment: In order to enhance the properties of glass, surface treatment is a necessary step. Don't listen surface treatment is a simple thing. In fact, there are many kinds of surface treatments. Common surface treatment methods include coating, acid etching, sand blasting, etc. The coating is to improve the anti-ultraviolet, anti-reflection and anti-rubbing properties of the glass. Acid etching and sandblasting are generally used to make frosted glass, which increases the stealth and decorative effect of the glass. This is where the frosted glass surface gets its frosted feel.
Quality inspection
After the glass is made, it also needs to carry out strict quality testing before leaving the factory. Ensure it meets national and industry standards. Common testing items include:
Size and thickness testing: Ensure that the glass size and thickness are in line with the standard.
Optical performance detection: detection of glass transmittance, color difference and other optical properties. Make sure they meet optical standards.
Mechanical properties test: test whether the strength and hardness of the glass meet the indicators, so as to avoid damage caused by crushing.
Surface defect detection: The appearance of the glass is further examined. Including whether there are bubbles, scratches, cracks and other defects.
Packing and shipping
Glass products that have passed the quality inspection need to be packaged and transported. When packaging, the glass needs to be separated by a soft cushion. Prevent damage in transit. In the transportation process, special attention should also be paid to anti-shock and anti-pressure. Ensure the safe delivery of glass products to the destination.
Sum up
The manufacturing process of glass is a complex and delicate process. From the initial selection of raw materials, mixing materials, molten glass, glass forming, annealing, processing and surface treatment, to the final quality inspection and transportation. Each step requires precise control and strict management. Through scientific and reasonable manufacturing process, we can produce multi-functional glass products that meet customer needs. It can also be used in a variety of fields. In the future development, glass will continue to play its unique charm and bloom in various fields.
