Causes and Solutions for Lumps in Cable Extrusion

Lumps may occur during cable extrusion. The causes and solutions are analyzed below:

Types of Lumps

Resin lumps during plastification: Small crystalline points and particles distributed across the plastic layer surface.
Scorching lumps: Burnt materials on the plastic surface, particularly visible at polymer seams.
Contaminant lumps: Foreign particles on the surface, with impurities visible in cross-sections.
Poorly plastified lumps: Examination reveals undercured material inside the lumps.

Root Causes

Inadequate temperature control results in unplasticized material being extruded.
Poor-quality plastic containing hard-to-melt resins that aren't fully plasticized.
Contaminants entering through the hopper during feeding.
Excessively high temperatures causing material scorching.
Loose die head compression leading to material degradation and scorching.

Solutions

For resin-related lumps: Appropriately increase processing temperatures.
For contamination:
Strictly inspect raw materials for impurities
Prevent foreign object entry during feeding
Immediately clean the die head if contamination occurs
Purge residual material from the screw
For scorching:
Promptly reduce temperatures when overheating occurs
Clean the die head and screw if temperature adjustment proves ineffective
For plastification issues:
Adjust temperatures upward as needed
Reduce screw and haul-off speeds appropriately
(Note: All temperature adjustments should be made in 5-10°C increments for optimal process control.)