How to solve the plane parts problem
The area of plane injection molding parts is large, and the shrinkage is also large. Due to the extremely serious molecular orientation arrangement of large-scale injection molded parts, and the uneven cooling of the mold, the shrinkage rate of each direction of the injection molded parts is inconsistent, resulting in the deformation and distortion of the thin large-scale plane injection molded parts. Sometimes the support bone is designed on one side of the large plane injection molding part, and the injection molding part will certainly bend towards the boned side.It is a difficult problem to completely solve the deformation problem of large plane injection molding parts. In production, we summarized some more effective measures to improve the deformation problem:
1. Change the mold to multi-point water injection (usually three plate mold), and it is better to achieve more than 4 points for large plane injection parts with 24 a machine or above. In this way, the degree of orientation arrangement of molecules can be reduced, and the difference of anisotropy contraction inconsistency can be reduced.
2. Increase the mold temperature properly. ABS material is usually kept above 60 ℃ to reduce the cooling speed of injection parts, reduce the temperature difference deformation caused by chilling transition, and reduce the degree of molecular orientation.
3. The most important thing is to increase the injection or pressure maintaining pressure, and greatly extend the injection or pressure maintaining time, so as to increase the size of the injection part, reduce its shrinkage, and thus the degree of deformation will be significantly improved. Therefore, extending the time of glue injection or pressure holding (such as 10 to 15 seconds) has become an important means to solve the deformation problem.
4. If the above three measures fail to achieve the desired effect, the only way is to take the method of mold setting. Because most people don't use it very well, they need a little skill.
First of all, the injection parts should be out of the mold early, and then, when they are still in the state of dozens of degrees of high temperature (it should still be very hot, which is critical), they should be placed on the workbench and fixed with clamps. The key is that the design of the fixed clamps needs to be appropriate.
At the same time, the springback degree of injection parts should be considered. Generally, the springback will stop after 12 hours, and the lower the die temperature is, the greater the springback amount will be. The so-called correction must be over positive, so we should study the amount of over positive in production.