The powder and clinker matched by glass composition are melted in crucible kiln or tank kiln (see glass melting kiln). After melting, the glass liquid is clarified to be uniform, bubble-free, stone-free and stripeless, and then cooled to the viscosity range suitable for the corresponding molding method.
1. Blow molding
There are two ways of manual and mechanical blow molding. In artificial molding, the material is picked up from the crucible or the inlet of the kiln by hand-blown pipe and blown into the shape of a device in the iron mold or the wooden mold. Smooth circular products with rotary blowing method; surface with convex and concave patterns or shapes of non-circular products with static blowing method. First pick colorless material to blow into small bubbles, and then with small bubbles to pick colored material or opaque material to blow into the shape of a device is called nest blowing. With the color of easy-to-melt particles stained on the opaque package, various colors of natural melting flow, can be blown into natural scenery vessels; in color material stained with banded opaque material, can be blown into wire drawing vessels. Mechanical molding is used to blow large quantities of products. After blowing, the blow molding machine automatically forms the shape of the iron mold and removes the cap from the mold. It can also use pressure blow molding, first punching the material into small bubbles, and then continue to blow into the shape. It is more efficient and better quality than blowing machine.
2, compaction molding
During manual forming, the artificial pick is cut into the iron mould, driven by punching head, pressed into the shape of the machine, and demoulding after solidification. Automatic production of mechanical molding, large volume and high efficiency. Pressing molding is suitable for small products such as cups, plates, ashtrays, etc. that can exit the punch.
3. Centrifugal molding
In the rotating mold, the centrifugal force caused by the rotation makes the glass expand and close to the mold, and the glass is removed after setting the mold. Suitable for forming large glassware with uniform wall.
4. Free form.
It is also called die less molding. The material is repeatedly baked or modified by manual picking. Because it does not contact the mold, the glass surface is bright and the shape of the product is smooth. Finished products are also called kiln glass products.