Causes and countermeasures of molding failure of PVC injection molding products

June 19, 2019

Causes and countermeasures of molding failure of PVC injection molding products

 

 

Short shot
(1) The melt temperature is too low. The molding temperature should be appropriately increased.
(2) The molding cycle is too short. Should be extended appropriately.
(3) The injection pressure is low. Should be properly improved.
(4) The injection speed is too slow. Should be accelerated as appropriate.
(5) Insufficient supply. The amount of feed should be increased.
(6) The mold temperature is too low. Should be properly improved, especially to properly set the cooling circuit of the mold to keep the mold temperature uniform.
(7) The wall of the product is too thin, and the resistance of the molten material is too large. The physical structure of the product should be reasonably adjusted where possible.
(8) The size of the gating system is too small. The gate and runner sections should be properly enlarged.
(9) The mold is poorly exhausted. The mold exhaust should be increased.
(10) The mold strength is insufficient. The rigidity of the mold should be as high as possible.

 

 

Flashing edge
(1) The melt temperature is too high. The barrel and nozzle temperatures should be properly lowered.
(2) The injection pressure is too high. Should be appropriately reduced.
(3) The injection speed is too fast. Should be appropriately slowed down.
(4) The holding time is too long. Should be shortened as appropriate.
(5) Too much feed. The amount of feed should be appropriately reduced.
(6) The clamping force is insufficient. The clamping force should be increased.
(7) The mold temperature is too high. Should be appropriately reduced.
(8) The setting of the insert is unreasonable. It should be adjusted according to the shape and mold structure of the product.
(9) The shape and structure design of the product is unreasonable. It should be adjusted reasonably if possible.
(10) The mold strength is insufficient. The rigidity of the mold should be as high as possible.

bubble
(1) The melt temperature is too high. Should be appropriately reduced.
(2) The molding cycle is too long. Should be shortened as appropriate.
(3) The injection pressure is too low. Should be properly improved.
(4) The injection cycle is too fast. Should be appropriately slowed down.
(5) The holding time is too short. Should be extended appropriately.
(6) The mold temperature is not uniform. The mold cooling system and flow should be properly set.
(7) The mold is poorly exhausted. The mold exhaust should be increased.
(8) The structural design of the product is unreasonable or the wall is too thick. It should be adjusted where possible.
(9) The gate or runner cross section is too small. Should be properly enlarged.
(10) The raw material is not sufficiently dried. The raw materials should be pre-dried.

 

 

Sink mark
(1) The injection pressure is too low. Should be properly improved.
(2) The holding time is too short. Should be extended appropriately.
(3) The cooling time is too short. Increase cooling efficiency or extend cooling time.
(4) Insufficient supply. The amount of feed should be increased.
(5) The mold temperature is not uniform. The mold cooling system and flow should be properly set.
(6) The shape of the product is unreasonable or the product wall is too thick. It should be adjusted where possible.
(7) The size of the gating system is too small. The gate and runner sections should be properly enlarged.
(8) The melt temperature is too high. Should be appropriately reduced.

 

 

Weld Line
(1) The melt temperature is too low. The barrel and nozzle temperatures should be properly increased.
(2) The injection pressure is low. Should be properly improved.
(3) The injection speed is too slow. Should be accelerated as appropriate.
(4) The mold temperature is too low. Should be properly improved.
(5) The size of the gating system is too small. The gate and runner sections should be properly enlarged.
(6) The mold is poorly exhausted. The mold exhaust should be increased.
(7) Foreign matter impurities are mixed into the raw materials. It should be cleared.
(9) The dosage of the release agent or stabilizer is excessive. The amount should be minimized.
(10) The raw material is unevenly colored. A more dispersible colorant should be used and the mixing time should be extended.
(11) The structural size of the cold feed hole is too small or improperly positioned. It should be adjusted reasonably.

 

 

Flow mark
(1) The melt temperature is too low. The barrel and nozzle temperatures should be properly increased.
(2) The injection pressure is too low. Should be properly improved.
(3) The pressure holding time is too short. Should be extended appropriately.
(4) The mold temperature is too low. Should be properly improved.
(5) The size of the gating system is too small. The gate and runner sections should be properly enlarged.
(6) The cold pocket in the mold is too small. Should be properly enlarged.
(7) The cooling circuit of the mold is not properly set. The design should be adjusted to maintain a uniform temperature across the mold.
(8) The raw material is unevenly colored. A more dispersible colorant should be used and the mixing time should be extended.

Charred and black lines
(1) The melt temperature is too high. The barrel temperature should be lowered appropriately.
(2) The molding cycle is too long. Should be shortened as appropriate.
(3) The injection speed is too fast. Should be appropriately slowed down.
(4) The screw back pressure is too high. Should be appropriately reduced.
(5) The gate cross-section size is too small. Should be properly enlarged.
(6) The mold is poorly exhausted. The mold exhaust should be increased.
(7) The raw material is poorly dried. The drying temperature should be increased and the drying time should be extended.
(8) The amount of the release agent is too much. The amount should be minimized.
(9) The injection pressure is too high. Should be appropriately reduced.

 

 

Silver silk
(1) The melt temperature is too high. The barrel temperature should be lowered appropriately.
(2) The mold temperature is too low. Should be properly improved.
(3) Foreign matter impurities are mixed into the raw materials. It should be cleared.
(4) The raw material is poorly dried. The drying temperature should be increased and the drying time should be extended.
(5) The molding cycle is too long. Should be shortened as appropriate.
(6) The injection speed is too fast. Should be appropriately slowed down.
(7) The amount of injection slowdown is too small. Should be increased appropriately.
(8) The gate cross-section size is too small. Should be properly enlarged.
(9) The mold is poorly exhausted. The mold exhaust should be increased.
(10) The raw material is poorly dried. The drying temperature should be increased and the drying time should be extended.
(11) The injection pressure is too high. Should be appropriately reduced.

Surface scratch
(1) The injection pressure is too high. Should be appropriately reduced.
(2) The holding time is too long. Should be shortened as appropriate.
(3) The mold temperature is too low. Should be properly improved.
(4) The setting of the ejection device is unreasonable. The top-out cross-sectional area and the ejection point should be increased as much as possible.
(5) The draft is not sufficient. Should be increased appropriately.
(6) The melt temperature is too low. The barrel temperature should be increased appropriately.

 

 

Poor gloss
(1) The melt temperature is low. The barrel and nozzle temperatures should be properly increased.
(2) The molding cycle is too long. Should be shortened as appropriate.
(3) The mold temperature is low. Should be properly improved.
(4) The size of the gating system is too small. The gate and runner sections should be properly enlarged.
(5) The mold is poorly exhausted. The mold exhaust should be increased.
(6) Foreign matter impurities are mixed into the raw materials. The material should be removed or replaced.
(7) The amount of the release agent is too much. The amount should be minimized.
(8) The screw back pressure is too low. Should be properly improved.
(9) The raw material is poorly dried. The raw material should be dried and warmed.

Uneven color
(1) The barrel temperature is too high. The barrel temperature should be lowered appropriately.
(2) The molding cycle is too long. Should be shortened as appropriate.
(3) The raw material is unevenly colored. The material should be colored evenly.

Surface discoloration
(1) The melt temperature is too high. The molding temperature should be appropriately lowered.
(2) The molding cycle is too long. Should be shortened as appropriate.
(3) The size of the gating system is too small. The gate and runner sections should be properly enlarged.
(4) The mold is poorly exhausted. The mold exhaust should be increased.
(5) Foreign matter impurities are mixed into the raw materials. The material should be removed or replaced.
(6) The screw back pressure is too high. Should be appropriately reduced.
(7) The injection speed is too fast. Should be slowed down appropriately

 

 

Layered stripping
(1) The melt temperature is too low. The barrel and nozzle temperatures should be properly increased.
(2) The injection speed is too fast. Should be appropriately slowed down.
(3) Foreign matter impurities are mixed into the raw materials. Thorough removal or replacement of new materials should be carried out.
(4) The mold temperature is too low. Should be properly improved.

Warpage deformation
(1) The melt temperature is too low. The barrel temperature should be increased appropriately.
(2) The molding cycle is short. Should be extended appropriately.
(3) The injection pressure is too high. Should be appropriately reduced.
(4) The injection speed is too fast. Should be appropriately slowed down.
(5) The holding time is too long. Should be shortened as appropriate.
(6) The mold temperature is too high. Should be appropriately reduced.
(7) The gate cross-section size is too large. Should be appropriately reduced.
(8) The setting of the ejection device is unreasonable. The top-out cross-sectional area and the ejection point should be increased as much as possible.
(9) The mold strength is insufficient. The rigidity of the mold should be as high as possible.
(10) The mold cooling system is not properly set. The design should be adjusted to maintain a uniform temperature across the mold.

 

Poor release
(1) The feeding time is too long. Should be shortened as appropriate.
(2) The injection pressure is too high. Should be appropriately reduced.
(3) The cooling time is too long. Should be shortened as appropriate.
(4) There is too much feed. Should be appropriately reduced.
(5) The mold temperature is too high. Should be appropriately reduced.
(6) The mold is poorly exhausted. The mold exhaust should be increased.
(7) The setting of the ejection device is unreasonable. The top-out cross-sectional area and the ejection point should be increased as much as possible.
(8) The mold strength is insufficient. The rigidity of the mold should be as high as possible.
(9) The mold release angle is insufficient. Should be appropriately increased.
(10) The shape of the product is too complicated. It should be adjusted if possible.
countermeasures

 

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