Injection molding sink Mark– its causes and solutions
Sink mark: Cooling contraction in wall thickness, the material has a dent on stiffener or sinkhole phenomenon
The pressure of polymer – volume – the relationship between the injection mold temperature
Parts in different wall thickness appear easily sink mark
- The original design
- 1, The wall thickness is too large
- 2, The wall thickness is not uniform
- 3, Internal and external Angle
- Improved design.
- 1, To reduce the wall thickness
- 2, The wall thickness uniformity
- 3, Internal and external chamfering
Appear sink mark on parts in the plastic injection molding sink mark：
- Wall thickness T
- Draft Angle (D) 0.5 to 1.5
- The stiffener height (H) less than 5 T, average 2.5 T – 3 T
- Strengthen the spacing is greater than 2 t – 3 t
- Chamfering radius (R) 0.25 0.40 T
- The thickness of the stiffener (W) 0.4 T – 0.8 T
In order to ensure the strength, sinkhole diameter is generally diameter 2 times
The above two kinds of ways can make the sinkhole structure is strengthened
By analyzing the plastic injection molding decrease printer
Method to minimize the printer –China Injection Molding process
An increase in injection pressure
B late increase the pressure
C reduce shrink mark parts of the injection of express delivery
D reduce the mold temperature
E lower the temperature in the injection molding
In addition, to the sink mark, the production process will encounter shrinkage, then you need a different solution
