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Injection molding sink mark

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 Plastic products sink Mark-- its causes and solutions
Sink mark :Cooling contraction in wall thickness, the material has a dent on stiffener or sink hole 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 molding sink hole:

  • 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

Injection Mold Sink hole design sample 1

Injection Mold Sink hole design example 2

In order to ensure the strength, sink hole diameter is generally diameter 2 times

Injection Mold Sink hole design sample 3

Above two kind of way can make the sink hole structure is strengthened
By analyzing the plastic injection molding decrease printer

Method to minimize the printer --China  Injection Molding process
A increase of 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 sink mark, the production process will encounter shrinkage, then you need a different solution
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