Why Can’t Overly Quick Glue Injection Help Solve the Problem of Serious Shrinkage?

The relation between the glue injection and the shrinkage

To avoid the shrinkage, the first thing we think is to increase the injection pressure and extend the injection time. But if the injection speed has been adjusted very quickly, it is not conducive to solving the shrinkage problem. Therefore, when it’s difficult to eliminate shrinkage, you should reduce the injection speed.

By reducing the injection speed, a temperature difference between the front melt and the water inlet can be formed. It’s good for the solidification and shrinkage of the melt from far to near. And it’s helpful for the shrinkage position which is a little far from the water unlet to get a higher pressure supplement. That would be helpful to solve the problem.

For the reduction of injection speed, the temperature of the front melted glue is lower and its speed slows down. Besides, excessive flash will possibly not appear on the injection parts. The injection pressure and time can be increased and extended, which is more conducive to avoiding the serious shrinkage.

In addition, the effect will be more obvious if you adopt the last-stage end-filling at a slower speed, higher pressure, and longer time and the pressure-retaining method of gradually slowing down and pressurizing. Therefore, if it isn’t possible to inject the glue at a slower speed at the beginning. Then, it is also a good remedy to use this method from the late stage of injection.

However, it is worth reminding that if the filling is too slow, it won’t work. Because when the cavity is filled, the melt is completely frozen, just like the temperature of the melt is too low, there is no ability to compensate for the shrinkage in the distance.

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