Have you ever encountered deformation of products after injection molding? What exactly causes this situation? How to solve it?
In actual operations, product deformation often occurs. There are many reasons for deformation, such as temperature, mold design, plastic material, etc. In order to solve this problem, we need to make fine adjustments to production process, such as controlling temperature, improving mold design, selecting suitable plastic materials, etc.
Only through continuous research and exploration of technology can we better solve problem of product deformation. I hope that through this article, colleagues can have a deeper understanding of solutions to deformation problem in injection molding production process, provide some help and guidance for future production work.
Let’s take a look at this case

 

Adopt two-plate mold and side inlet glue

 

Mold flow analysis results
It can be seen from figure that melt front does not reach the bottom of product at the same time, and flow is unbalanced.
The overall deformation of product is: 0.6093mm~0.1709mm (effect of deformation magnified 10 times)
If red circle on the bottom of product bulges, it may become loose during assembly of product. This is consistent with actual situation.

 

Analysis of deformation in Z direction
Deformation amount in Z direction: 0.3621mm~-0.3549mm (effect picture after deformation magnified 10 times). External expansion of point A is about 0.08mm; external expansion of point B is about 0.09mm.

 

Improvement plan: Add ribs inside product to improve flow of melt (as shown in picture above). As shown in picture on the left, increase wall thickness at relevant parts to reduce flow resistance and balance flow of melt on both sides.

 

It can be seen from filling effect diagram that after product wall thickness is adjusted, plastic flow is relatively balanced, and melt front reaches bottom opening edge relatively simultaneously.

 

Improved analysis results
The overall deformation of product is: 0.5279mm~0.1849mm (rendering after magnifying deformation 10 times). It can be seen from the overall deformation diagram of product that bottom surface of product has shrunk inward as a whole, making it an improvement compared to original plan.

 

Deformation amount in Z direction: 0.3001mm~-0.3102mm (result of deformation magnified 10 times). It can be seen from analysis results that point A shrinks approximately 0.12mm and point B shrinks approximately 0.13mm. (Original design: Expansion of point A is about 0.08mm; expansion of point B is about 0.09mm. )

 

Improvement plan two: add overflow well
Add an overflow well at the location shown in product diagram to achieve filling balance.

 

It can be seen from filling effect diagram that after adding the overflow well, purpose of filling balance is achieved.

 

The overall deformation of product is: 0.7048mm~0.1763mm (rendering after deformation is magnified 10 times). It can be seen from the overall deformation diagram of product that bottom surface of product has shrunk inward as a whole, making it an improvement compared to original plan. Maximum deformation occurs at overflow well, as shown in figure above.

 

It can be seen from analysis results that point A shrinks approximately 0.10mm and point B shrinks approximately 0.08mm. (Original design: Expansion of point A is about 0.08mm; expansion of point B is about 0.09mm. )
Compare results

After design change, flow became more balanced, causing side wall of product to change from expansion to contraction, and deformation was significantly improved. Recommended to try.
Here is a case where product was changed after analysis. Sometimes product problems cannot be solved by adjusting machine. This requires specific data to understand cause of problem and put forward improvement plans in a targeted manner, so that we can better understand cause of problem. Good to solve problem.