The following are the common problems with insert molding products, which are also the difficulties for engineers to solve this type of mold.
Overflow of glue
It often occurs in the area where the R angle of the insert is used for sealing. Because the accuracy of the R angle after the insert is bent does not reach the theoretical size of the drawing, a gap will be left when it is matched with the mold, causing plastic overflow. The thicker the material of the insert, the harder the hardness, the greater the elastic deformation after stamping, and the more obvious the overflow of glue. Therefore, try to avoid using the R angle for sealing, or suggest that customers try to make the R angle as large as possible to reduce the risk of overflow of glue. If the accuracy of the R angle cannot be further improved, the fitter needs to match the mold according to the actual R angle.
Bonding force of insert molding products
Because the insert molding products are combined with the insert and the plastic part by structure, the product will have insufficient bonding force. Insufficient bonding force will cause various appearance and performance defects, thus affecting the use of the product. For this problem, it can be improved by modifying the bonding area or bonding method between the plastic part and the insert. Since changing the structure of the insert requires changing the structure of the die, there is a certain risk of large movement. Therefore, it is possible to consider changing the structure of the insert on each side for testing, and then improve the die after confirming that the problem can be solved.
Deformation problem
The most difficult problem to solve for insert molded products is their deformation. Because the inserts in the product will not shrink, the plastic part will become cold when encountering the inserts during the filling process, making it impossible to maintain pressure normally, and it will easily cause deformation after cooling and shrinkage. Solving the deformation problem is difficult and requires many attempts from different aspects.
Generally, it can be solved from the following aspects. First, consider whether the shrinkage deformation is caused by insufficient bonding force between the plastic part and the insert. Secondly, see whether the arrangement of the water channels on the mold can be improved to eliminate shrinkage deformation caused by uneven cooling. , in addition, the method of material change can be used to take samples to verify the deformation or change the location and number of gates. The first two methods only make changes and improvements in the mold, while the latter two methods are fundamentally tried. The general effect is more significant, but the cost of the experiment is also higher. Therefore, to solve such problems, we can start with small things first and then make big changes to save costs and time.
The development of insert molds is an arduous task. Many new problems often arise due to differences in materials, mold structures and molding processes. Injection mold design engineers should conduct careful analysis to find out the key to the problem and strive to shorten the time to solve the problem.