Glass is a colorless (white glass) transparent amorphous inorganic substance made of quartz sand, limestone, feldspar, soda ash, clarifier, colorant/decolourant, flux, broken glass and other raw materials through high-temperature melting, molding, annealing and cutting. Glass has a series of very valuable characteristics: transparency, hardness, good corrosion resistance, heat resistance, electrical and optical properties; Products of various shapes and sizes can be made by various molding methods; Its properties can be changed by adjusting its chemical composition to meet different application requirements. In particular, it is rich in raw materials and low in price, so it has been widely used and plays an important role in the national economy. 1. ingredients, according to the designed bill of materials, weigh all kinds of raw materials and put them into a blender to mix evenly. The main raw materials of glass are quartz sand, limestone, feldspar, soda ash and boric acid. 2. Melting: the prepared raw materials are heated at high temperature to form uniform bubble-free glass liquid. This is a very complicated physical and chemical reaction process. The melting of glass is carried out in a furnace. There are mainly two kinds of melting furnaces: one is crucible furnace, in which glass frit is filled outside the crucible and heated. Only one crucible is put in a small crucible kiln, and as many as 20 crucibles can be put in a large crucible kiln. Crucible kiln is intermittent production, and now crucible kiln only produces optical glass and colored glass. The other is the tank kiln, in which the glass frit is melted and the open flame is heated above the glass surface. The melting temperature of glass is mostly 1300 ~ 1600 ゜ C, and most of them are heated by flame and a few by current, which is called electric melting furnace. At present, kilns are all continuously produced. Small kilns can be several meters, and large kilns can be as big as more than 400 meters. 3. Molding is to transform molten glass into a solid product with a fixed shape. Molding must be carried out within a certain temperature range, which is a cooling process. Glass first changes from a viscous liquid to a plastic state, and then to a fragile solid state. Molding methods can be divided into two categories: manual molding and mechanical molding. A. artificial molding. There is also (1) blowing, which uses a nickel-chromium alloy blowing pipe to pick a mass of glass and rotates in the mold while blowing. Mainly used for forming glass bubbles, bottles, balls (used for drawing glass) and so on. (2) Wire drawing: After blowing into small bubbles, another worker sticks them with a top plate, and the two men pull them while blowing, which is mainly used to make glass tubes or rods. (3) Pressing: Pick a mass of glass, cut it with scissors to make it fall into the female die, and then press it with the male die. Mainly used for forming cups, plates, etc. (4) Free form: After selecting materials, directly make handicrafts with tools such as pliers, scissors and tweezers. B. mechanical molding. Due to the high labor intensity, high temperature and poor conditions, manual molding has been replaced by mechanical molding except free molding. In addition to pressing, blowing and drawing, mechanical forming also includes (1) calendering method, which is used to produce thick flat glass, carved glass and laminated glass. (2) Production of optical glass by casting method. (3) Centrifugal casting is used to manufacture large-diameter glass tubes, utensils and large-capacity reaction tanks. This is to inject the glass melt into a high-speed rotating mold, so that the glass clings to the mold wall due to centrifugal force and rotates continuously until the glass hardens. (4) Sintering method, which is used to produce foam glass. It adds foaming agent to glass powder and heats it in a covered metal mold. Glass forms many closed bubbles during heating, which is a good heat and sound insulation material. In addition, there are vertical pulling method, flat pulling method and float method to form flat glass. Float method is a method of making glass flow float on the surface of molten metal (tin) to form flat glass. Its main advantages are high glass quality (smoothness), fast drawing speed and large output. 4. Annealing, the glass has undergone drastic temperature change and shape change during the forming process, leaving thermal stress in the glass. This thermal stress will reduce the strength and thermal stability of glass products. If it is directly cooled, it is likely to break itself during the cooling process or during the subsequent storage, transportation and use (commonly known as glass cold explosion). In order to eliminate the phenomenon of cold explosion, glass products must be annealed after molding. Annealing is to keep the temperature within a certain temperature range or slow down the temperature for a period of time to eliminate or reduce the thermal stress in the glass to an allowable value. In addition, some glass products can be hardened to increase their strength. Including physical hardening (quenching), used for thick glass, desktop glass, automobile windshield, etc. ; And aviation glass. The principle of hardening is to produce compressive stress on the glass surface and increase its strength.