(59) Corrugation Injection Molding Process Defect Handling Manual (65 types)

(1) What is a ripple (appearance)?
Corrugation refers to the appearance of wrinkles on the surface of a molded product. Usually occurs in situations where the injection speed is slow and the surface layer cures faster than resin filling.
(2) Causes of ripple formation
(2-1) Injection speed is too slow
When the injection speed is too slow, it will not be possible to form a jet stream, and the surface will be concave and convex, resulting in "ripples". There is also a secondary reason: for example, when the product is thicker and the gate is smaller, the actual filling speed will become slower, resulting in easy formation of ripples.
Waves due to jet turbulence
(2-2) Low mold temperature
When the mold temperature is low, the surface layer will solidify faster, and the difficulty of jet flow will increase, which is easy to generate ripples.
(3) Countermeasures for corrugation
(3-1) Accelerate injection speed
This is the most effective method. It can basically eliminate ripples by increasing the injection speed.
However, if the molded product is thicker and the gate is smaller, the actual filling speed will become slower, so this should also be noted.
(3-2) Slow down surface curing
Specifically, it is necessary to increase the mold temperature. In this way, the jet flow will become somewhat easier, but also less prone to generating ripples.