塑料成型
1.3 Dark streaks1.4 Color streaksThe cause for the formation of streaks can be deter-mined in many cases only after costly investigations,especially as the appearance of burning and moisturestreaks is similar.Extensive knowledge of the plastic,the mold design and the processing are indispensablefor overcoming the problem.Before launching expen-sive and time-consuming investigations the followingpoints should be checked in the sequence given andif necessary optimized:
Melt temperatureInjection speed
Residence time in the cylinderBack pressure
Moisture content of granulesMold venting
Cleaning of the plasticising unitScrew recovery speed
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