1. Ingredients, according to the designed material recipe, weigh all kinds of raw materials and mix them evenly in a mixer. The main raw materials of glass are: quartz sand, limestone, feldspar, soda ash, boric acid, etc.
2. Melting, the prepared raw materials are heated at high temperature to form a uniform glass liquid without bubbles. This is a very complex physical and chemical reaction process. The melting of glass takes place in a furnace. The melting temperature of glass is mostly at 1300~1600゜C. Most of them are heated by flames, and a small amount of them are heated by electric current, which are called electric furnaces.
3. Forming is to transform the molten glass into a solid product with a fixed shape. Forming must be carried out within a certain temperature range. This is a cooling process. The glass first changes from a viscous liquid state to a plastic state, and then into a brittle solid state. Forming methods can be divided into two categories: artificial forming and mechanical forming.
A． Artificially shaped. There is also (1) blowing, using a nickel-chromium alloy blowpipe, picking a ball of glass and blowing it while turning it in the mold. Mainly used to form glass bubbles, bottles, balls, etc. (2) Drawing, after blowing into small bubbles, another worker sticks it with the top plate, and the two are blowing and pulling, which is mainly used to make glass tubes or rods. (3) Pressing, pick a group of glass, cut it with scissors and drop it into the die, and then press it with the punch. Mainly used to form cups, plates, etc. (4) Free forming, after picking materials, use pliers, scissors, tweezers and other tools to directly make handicrafts.
B． mechanical forming. The intensity of labor is big, because artificial forming temperature is high, the condition is poor, so, except the free forming, most have been replaced by mechanical forming.
Fourth, annealing, the glass has undergone intense temperature changes and shape changes during the forming process, and this change leaves thermal stress in the glass. This thermal stress reduces the strength and thermal stability of the glass article. If it is directly cooled, it is likely to break by itself during the cooling process or during subsequent storage, transportation and use (commonly known as cold burst of glass).