Today we are continuing to discuss the 3rd case for the sink mark, we will show what we would do when we face the sink mark problem.

1. Basic information: PC combination transparent block, poor shrinkage
2. Description: there is not enough holding pressure time, but it is easy to cause flash by increasing the injection pressure.
3. Improvement: Increase the holding pressure time (with a pressure of 6MPa, keep pressure for more than 7 seconds, the shrinkage problem is improved).
There is shrinkage when the holding time is 3 seconds. No shrinkage at 7 seconds.

How to determine the correct holding pressure time:
1. Set the holding pressure time to a slightly longer length.
2. Raise the pressure and look for pressure when no shrink.
3. After the holding pressure is determined, the holding time is gradually shortened to find the gate sealing time. At this time, the appearance of the molded part and the weight of the molded article can be continuously confirmed.
4. Set the holding pressure time as: 1~2sec of the upper and lower floating range of the gate sealing time.

How to find the gate sealing time?
In order to find the gate sealing time, it is possible to gradually change the holding time to observe the weight change of the molded part. Generally shown in the figure below. Appearance: 7sec is better, from the analysis chart, the sealing time is 8sec.