Molds & Tooling
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Product has silver streaks, poor plasticization, or unstable color
Problem Phenomenon
The product has silver streaks, poor plasticization, or unstable color, related to the screw back pressure setting
Cause Analysis
Back pressure too low, insufficient venting, silver streaks and bubbles
Back pressure too high, excessive shear, burning and degradation
Unstable back pressure causes plasticization fluctuation
Back pressure and screw speed not matched
Back pressure setting not adjusted according to cellulose acetate butyrate characteristics
Solution
Reasonably set back pressure 5-10MPa
Match back pressure with speed to ensure uniform plasticization
Stabilize back pressure control
Appropriately increase back pressure for venting
Avoid excessive back pressure increasing shear
Key Takeaway
Back pressure needs to match speed, balancing venting and shear
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