Void in MIM Smartphone Lens Ring

MIM process manufacture notes that void is a common defect in MIM process. Looking at the reason for void based on our last experience of UAV remote control metal button project.

There are two reasons for inner space within finish products:

1. Occurred in thick part, resulting from contraction after central cooling
2. Caused by volatile decomposition of plastic, air or water

The causes and treatment:
-  injection pressure is too low, holding time is too short.

- the back pressure is too low
- material temperature is too high, sticking for too long time
- improper design of product thickness
- mould flow channel or injection gate is too small

 --don’t dry material enough

- spray too much mold release agent