Almost all molds have mold scale problems during injection molding, and injection molds are no exception. The formation of mold scale in injection molds is largely due to the residue of additives, and of course there are other reasons. So, what are the more common types of mold scale? In the face of stubborn mold scale, how should we properly handle and prevent it?

1. Types of mold scale
Various additives produce specific types of mold deposits. Fire retardants react at high temperatures, forming decomposition and possibly mold scale products. Under the influence of excessive heat or extreme shear, the impact agent will separate from the polymer and remain on the surface of the cavity to form mold deposits.
The pigments in thermoplastic engineering plastics melt at high temperatures, which will reduce the thermal stability of the molding raw materials, resulting in the combination of degraded polymers and decomposed pigments to form mold deposits. Modifiers/stabilizers and other additives may stick to surfaces and cause mold fouling on particularly hot parts (eg cores) on injection molds. In this case, measures should be taken to achieve better mold temperature control or use of special stabilizers.

2. Countermeasures for sudden mold scale
If mold fouling occurs suddenly, it may be due to a change in molding conditions, or due to changing a different batch of molding raw materials. The following suggestions can help improve mold fouling. First, measure the melt temperature and visually inspect the melt for signs of decomposition (eg, burnt particles). At the same time, check whether the molding raw materials are contaminated with foreign substances and whether the same cleaning raw materials are used. Check the exhaust state of the injection mold; again, check the operating machine: use dye-colored molding raw materials (except black), turn off the injection molding machine after about 20 minutes, remove the nozzle, the connecting seat, and if possible, remove it together with the screw, check whether the raw material is There are burnt particles,
Compare the color of raw materials and quickly find out the source of mold scale. Surprising causes of mold scale defects have been found in many cases. This technique is more suitable for smaller
Plastic machine, the maximum screw diameter is 40mm. The elimination of mold deposits also results in a definite improvement in the quality of the part when molding other raw materials. The above countermeasures also apply to molding with hot runner systems. Mold scale leads to appearance defects of injection molded parts, especially parts with surface etching, which can be repaired by sandblasting.
In the process of injection molding of injection molds, although it is difficult to completely avoid the problem of mold scale, as long as the root cause of the problem is found, handled and prevented in time, it is believed that the occurrence of mold scale problems can be reduced and the normal use of the mold can be guaranteed. For more information about injection molds, please feel free to visit this site for inquiries.