100 Common Troubleshooting Tips For Twin-Screw Extrusion Lines (Part 2)

3. Product Surface & Appearance Quality

41. Sharkskin texture on surface: Excessive extrusion speed leads to melt fracture.
Solution: Slow down production speed moderately.

42. Bubbles inside finished products: Raw materials contain excessive moisture.
Solution: Fully dry materials before production.

43. Yellow discoloration: Processing temperature is too high or stabilizer content is insufficient.
Solution: Lower barrel temperature and check formula ratio.

44. Black spots on surface: Carbonized material falling off from equipment inner walls.
Solution: Clean the whole production line thoroughly.

45. Brittle final products: Incomplete plasticization or excessive filler addition.

46. Wavy surface patterns: Poor mixing of different raw materials.

47. White flecks: Color masterbatch fails to disperse evenly.

48. Surface dents and cavities: Inadequate cooling or insufficient packing pressure.

49. Dull surface luster: Low die temperature or excessive lubricant.

50. Surface pits: Cooling water splashes onto the die lip.

51. Crystalline particles inside products: Material contamination or uneven molecular weight distribution.

52. Bent finished products: Misalignment between sizing unit and haul-off machine.

53. Unstable product dimensions: Fluctuating running speed of puller.

54. Rough inner surface: Low temperature of die mandrel.

55. Unusual odor from products: Polymer degradation caused by overheating.
Solution: Check and adjust all temperature settings at once.

56. Mottled surface: Uneven distribution of cooling water.

57. Poor flexibility: Excessive molecular orientation during processing.

58. Internal voids: Poor devolatilization effect of the vacuum system.

59. Transverse ripples on surface: Belt slippage or mechanical vibration of puller.

60. Low transparency: Cooling speed is too slow for crystalline plastics.

4. Sizing, Cooling & Pulling System

61. Vacuum sizing failure: Air leakage in vacuum pipeline or damaged water seal.

62. Cooling tank water overflow: Blocked water return pipe.

63. Puller belt slippage: Insufficient clamping pressure or dirt on belt surface.

64. Cutter stops working: Faulty proximity switch or position deviation.

65. Uneven cutting section: Dull cutting blade or mismatched cutting speed.

66. Static electricity in cooling water: Production line lacks reliable grounding.

67. Rapid wear of sizing sleeve: Raw materials contain a large amount of hard filler.

68. Slow cooling effect: High water temperature or chiller malfunction.

69. Puller fails to keep pace: Motor power is not enough.

70. Cut surface damaged by cutter: Overly tight clamping force.

71. Material tilter not working: Insufficient air pressure for pneumatic components.

72. Vibration inside cooling tank: Unbalanced water pump rotor.

73. Inaccurate vacuum gauge reading: Blocked connecting pipe.

74. Puller belt deviation: Loose or misaligned mounting bolts.

75. Uneven cutting length: Slipping measuring wheel or encoder fault.

76. Material stacking at sizing inlet: Cooling water sprays too far forward.

77. Products floating in water tank: Lack of effective hold-down device.

78. Clogged spray nozzles: Limescale formed by poor water quality.

79. Abnormal noise from puller: Dry bearings without timely lubrication.

80. Loud running noise of cutter: Guide rails lack lubricating oil.

5. Raw Materials & Formulation

81. Material discoloration: Colorant and heat stabilizer cannot withstand processing temperature.

82. Sudden change of melt flow property: New batch of raw materials has inconsistent performance.

83. Poor material conveying: Excess lubricant causes screw slipping.

84. Low impact resistance: Too high proportion of recycled materials.

85. Bad filler dispersion: Premixing time is not enough.

86. Low melt strength: Selected resin grade does not match production demands.

87. High material moisture: Damaged heating parts of drying equipment.

88. Powder agglomeration: Excessively high ambient humidity.

89. Additive precipitation and migration: Poor compatibility between different ingredients.

90. Products prone to aging: Antioxidants or UV absorbers are missing in formula.

91. Large heat shrinkage: Internal stress of products is not fully released.

92. Melt fracture: High molecular weight or low processing temperature.

93. Severe static accumulation: No antistatic agent added.

94. Fast equipment wear caused by filler: Fillers without surface treatment.

95. Foreign particles in products: Damaged or broken screen packs.

96. Inefficient purging during color change: Improper purging material selected.

97. Hopper bridging: Uneven particle size of raw materials.

98. High production cost: Filler ratio is not optimized reasonably.

99. Unstable processing parameters: No voltage stabilizer equipped on site.

100. Operation errors: Non-standard operation by on-site staff.

Supplementary Note

Most common faults above can be avoided or solved via daily inspection, regular cleaning and routine maintenance. This guide serves as a practical reference for on-site operation and maintenance. If you encounter complex or recurring problems, please contact our professional technical team for support.