The Firing Elements of Enamel Products
Firing means that the dry powder coated body enters the firing furnace, and the dry powder layer is melted under the established enamel firing process conditions, the enamel groundcoat is adhered to the metal body, and the covercoat is bonded to the groundcoat layer and produces turbidity, luster and color, to achieve due physical and chemical properties. The quality of firing will directly affect the quality of enamel products. In this article, the enamel powder manufacturer Nolifrit will introduce the firing elements of enamel products in detail to avoid defects in enamel products caused by firing process.
1. Reasonable firing system
The key conditions for firing enamel products are the temperature, time and indoor atmosphere during firing. Each kind of enamel frit has a certain range of melting and softening temperature, and the firing temperature must be determined within this range. In most cases, the enamel product must be fired in an oxidizing atmosphere. The firing time is depend on the shape, size and structure of the enamel product.
2. Heat evenly
When firing, heating all parts of the enamel product with basically same heat, which is called uniform heating. Due to the different positions in the furnace and the different shape of the iron billet during firing, there may be temperature differences in various parts of a same dry powder coated metal body. In order to reduce the degree of uneven heating of the products, attention should be paid to the height of the hanging basket and the burning rack, the arrangement of the positions of the products in the furnace, the mutual distance between the products, and the mass ratio of the products to the hanging basket and the burning rack, etc.
3. Uniform cooling
After the enamel product is fired, it is in a hot state when it is out of the furnace. During the cooling process, the iron billet and the enamel layer shrink inconsistently, causing the product to produce internal stress. When the internal stress exceeds the tensile or compressive strength of the enamel layer, it will cause defects such as cracks or peeling of the porcelain enamel layer, especially at the edges and corners of the product, because the radius of curvature is small, the stress is concentrated there, and the peeling is most likely to occur . If the part of the product cool unevenly, causing excessive concentration of internal stress in the part, the above defects are more likely to occur.
Firing process is one of the most critical processes in the production of enamel products. It plays a very important role in the appearance and internal quality of the product. The quality of the previous processes will be reflected after firing process.