EXTRUSION PROCESS GUIDE
Color Variation, Streaks, and Dispersion Control in Extrusion
Extrusion streaks and shade variation may result from unstable feeding, poor dispersion, temperature profile, die buildup, or raw-material variation acting alone or together.
Color Masterbatch Technical Team · 2026-08-13 · 10 min
What Does the Appearance of the Line Tell?
Continuous, intermittent, pattern-oriented or random traces indicate different control points. The error onset time and its relationship to line speed should be recorded.
continuous line
Continuous streak pattern accumulation in the same location may be associated with a region in the screen or flow channel. Mold cleanliness and trace position are compared together.
Intermittent tone change
Periodic fluctuation may indicate rhythmic change in feeder, mixer, screw filling or raw material flow. Weighing and turnover records are checked.
Dispersion and Feed Control
Even if the masterbatch is chosen correctly, homogeneous results cannot be obtained if it is transported irregularly. Granule flow, premix and screw shear effects should be evaluated without separating them from each other.
Dosator calibration
Target percentage and actual consumption are compared on a shift-by-shift basis. The volumetric setting needs to be re-verified whenever the granule density or size changes.
Mixture and screw effect
Short mixing may leave segregation or low shear pigment clumps visible in the chamber. Melt temperature and pressure should also be monitored when changing the screw speed.
Control Order for Line Trial
Instead of changing all parameters at the same time, material, dosage and process steps are verified sequentially. Samples are taken from the same point in each step.
Materials and cleaning first
Raw material and masterbatch lots, drying, previous color, filter and mold cleaning are verified. Problematic and good shift records are juxtaposed.
Then process window
Temperature zones, screw speed, pressure, line speed and cooling are controlled with a single variable approach. When a solution is found, the approved range is added to the work instruction.
Short Technical Answers
What causes color streak in extrusion?
Mold accumulation, uneven dosing, poor mixing, insufficient dispersion, previous color residue or temperature deviation may cause streaking.
Is masterbatch granule size important?
Yes. Too different granule size or density from the main raw material can increase segregation and uneven feeding in the hopper.
How to verify dispersion problem?
Controlled sample, microscopic or surface inspection, sieve inspection and comparison with stationary process; It helps distinguish whether the problem is material or feeding.
Share line photo, sample and line parameters; Let's create the dispersion and process control sequence together.
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