It is also known to most people that the shrinkage of injection
parts is easy to occur when the melt temperature is too high. If
the temperature is lowered appropriately by 10-20 C, the shrinkage
problem will be improved.
However, if the shrinkage occurs in a relatively thick part of the
injection part, then the melt temperature is too low, such as close
to the lower limit of the melt temperature, which is not conducive
to solving the shrinkage problem, or even more serious, the thicker
the injection part is, the more obvious the situation is.
The reason is similar to the die temperature too low, the melt gel
condensates too fast, and the temperature difference between the
shrinkage water level and the nozzle can not be formed, so the
feeding channel of the shrinkage water level will be blocked
prematurely, and the solution of the problem will become more
difficult. It can also be seen that the faster the melt
condensation speed, the more unfavorable to solve the shrinkage
problem, PC material is a very fast condensation raw material, so
its shrinkage problem can be said to be a big problem of injection
moulding.
In addition, too low melt temperature is also not conducive to
increase the overall shrinkage, leading to an increase in the
amount of concentrated shrinkage, thus aggravating the shrinkage
problem.
Therefore, when adjusting the machine to solve the difficult
shrinkage problem, it is very important to check whether the melt
temperature is too low. In addition to looking at the thermometer,
it is more intuitive to check the melt temperature and fluidity by
air injection.
