1, the formation of the scale
Almost all thermoplastic plastics injection molding will occur when scaling. When the functional requirements of the final product must be mixed with the relevant additives (such as modifier, fire agent, etc.), the molding process, these additives are very likely to remain in the mold hole surface, resulting in the formation of scale.
There are other reasons for the formation of scale, the most common reasons are as follows:
Thermal decomposition products of ▶ raw materials;
▶ Injection molding, melt flow extreme shear force;
▶ Improper exhaust;
As the result of the mold scale is often a combination of different factors, and seek to discover what these models are caused and how to prevent, very troublesome, and the scale of the mold will be a few days after the formation.
2. Category of scale
1 a variety of additives to produce specific categories of mold scale. Fire agents react at elevated temperatures, forming decomposition and potentially producing scaling products. Under the influence of excessive high temperature or extreme shear force, the anti-impact agent will be separated from the polymer and the mould scale is formed in the mould cavity surface.
2. The pigment of thermoplastic engineering plastics melts at elevated temperatures, which reduces the thermal stability of the molding material, resulting in the degradation of the polymer and the decomposition of the pigment combination form the scaling.
3 A specially hot part of the mould (such as mould core), modifier/stabilizer and other additives may adhere to the surface and cause the scale. In this case, measures must be taken to achieve better mold temperature control or use special stabilizers.
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