Talking about why the injection mold product has a warped edge?

2021-03-23 18:53:32 admin

In precision injection molding, there are many situations, among them, mold warping is one of them


Edge warping: refers to plastic parts that are not formed according to the designed shape, but the surface is distorted. The warpage of the plastic parts is caused by the uneven shrinkage of the formed plastic




cause:


1. The temperature of the material pipe is too low; the temperature of the nozzle is too low;


2. The melting temperature is too low or the injection pressure is too high;


3. Improper holding pressure or holding time;


4. Improper residence time; improper cycle time;


5. Insufficient slow charge;


6. The temperature difference between male and female molds is large; mold temperature is too low


7. The difference between the thickness and thickness of the mold cavity is too large


8. Improper number or location of gates


9. The gate, runner or gate is too small or too long


10. Uneven ejection


Analysis of product warpage defects and elimination methods:


Defect analysis and elimination method


Insufficient/uneven cooling ———— It can be ejected after being fully cooled in the mold cavity and completely hardened; it can also reduce the mold temperature and extend the cooling time.


The ejector rod causes —— grind the core, reduce the ejection resistance, or increase the draft angle, add ejector rods in the difficult ejection part, or change the ejection method.


Caused by forming strain————Increase the mold temperature, increase the melt temperature, reduce the injection pressure, improve the flow conditions of the pouring system, etc. can reduce the shrinkage rate, the difference in the direction, the most important thing is to pay attention to the product The wall thickness is the same.


Crystalline plastics-The correction method used is to make the dynamic and static molds have a certain temperature difference. The deformation can be corrected by adopting a temperature that causes strain on the other side of the warpage. Sometimes the temperature difference is as high as 20 degrees or more, but it must be very Evenly distributed.




The method of correcting the warped edge of the product —— The product to be corrected is placed on the correcting tool, and the weight of the object is added to the warped edge, but the weight of the heavy object must be clearly determined in the same position as the position.