Large area of flat injection molded parts, shrinkage is also very large. Due to the molecular orientation of large injection molded parts is very serious, coupled with uneven cooling of the mold, resulting in inconsistent shrinkage of the injection molded parts in all directions, resulting in a thin flat injection molded parts Deformation and distortion are very likely to occur. Sometimes one side of a large-surface injection molded part is designed to support the bone. At this time, the injection molded part must also be bent toward the boned side.
It is indeed a difficult problem to completely solve the problem of deformation of large-area injection molded parts. In production, we have summarized some of the more effective measures to improve the problem of deformation:
1. The mold is changed into multi-point water (usually three-plate molds). Large-area injection molded parts above 24 amps are better than 4 points. This can reduce the degree of molecular alignment and reduce the inconsistency gap.
2. Appropriately increase the mold temperature, ABS material is usually kept above 60 °C to reduce the cooling rate of the injection molded parts, reduce the temperature difference caused by the chilling transition and reduce the degree of molecular alignment.
3. The most important one is to increase the injection pressure or holding pressure, and greatly extend the time for injection or holding pressure, so as to increase the size of injection molded parts and reduce the amount of shrinkage. The degree of deformation will therefore be obvious. Improvements. Therefore, prolonging the time for injection or holding pressure (such as extending 10 to 15 seconds) has become a common and important means for us to solve deformation problems.
4. If the above three measures fail to achieve the desired results, only the use of standardized methods will be adopted. Because most people are not very good at using them, they need a little skill.
to sum up:
First of all, the injection molded parts should be ejected early, and then, by still being in the state of several tens of degrees of high temperature (should still be very hot, this is very critical), placed on the workbench with the fixture shape, the key is to set the fixture Design needs to be appropriate.
At the same time, the degree of rebound of the injection molded parts must also be considered. Generally, springback will stop after 12 hours, and the lower the die temperature is, the greater the springback will be. The so-called overriding must be overcorrected. Therefore, the overpressure must be studied during production. The amount of