The shrinkage problem of hard rubber parts (surface concave
shrinkage and internal shrinkage) is caused by the defect that the
space left by the concentrated shrinkage can not be adequately
supplemented by the melt from the direction of the inlet when the
melt is cooled and contracted. Therefore, factors that are not
conducive to the subsidy will affect us to solve the problem of
shrinkage.
Most people know that die temperature is too high to cause
shrinkage problems, usually like to reduce the temperature of the
die to solve the problem. But sometimes if the die temperature is
too low, it is not conducive to solve the shrinkage problem, which
is not noticed by many people.
Mold temperature is too low, melt glue cooling is too fast,
slightly thicker glue level is far from the water inlet. Because
the middle part is cooled too fast, the shrinkage channel is
blocked and the melt glue can not be adequately supplemented in the
distance, which makes the shrinkage problem more difficult to
solve. The shrinkage problem of thick injection parts is
particularly prominent.
Moreover, too low die temperature is not conducive to increase the
overall shrinkage of injection parts, so that the concentrated
shrinkage increases, shrinkage problem is more serious.
Therefore, when solving the difficult shrinkage problem, it is good
to remember to check the die temperature. Experienced technicians
usually touch the surface of the die cavity with their hands. Each
material has its appropriate die temperature. For example, the
shrinkage of PC material will be improved if the hole is properly
pressed, but if the die temperature is too high, the shrinkage of
injection parts will occur.
