Analysis of Scorching During Cable Extrusion Process

What causes scorching during cable extrusion? The details are as follows:

Manifestations of Scorching

Abnormally high temperature readings or malfunctioning temperature control instruments causing plastic overheating and scorching.
Visible smoke at die exit with strong irritating odor, accompanied by crackling sounds.
Granular scorch marks appearing on plastic surface.
Continuous air bubbles along polymer seams.

Causes of Scorching

Excessive temperature control leading to material scorching.
Accumulated scorched particles in uncleaned screw over prolonged use.
Prolonged heating duration causing material degradation.
Plastic decomposition during extended machine downtime without proper cleaning.
Resin decomposition from frequent die/color changes.
Loose die compression cap causing material aging.
Malfunctioning temperature control instruments creating overheating.

Scorching Prevention Methods

Regular inspection of heating systems.
Scheduled thorough cleaning of screw and die head.
Strict adherence to prescribed heating parameters; report system malfunctions immediately.
Prompt and complete die/color changes to prevent contamination.
Secure die bush compression cap after adjustment.
Immediate cleaning of die and screw upon scorch detection.
(Note: Critical temperature zones should maintain ±5°C tolerance per ASTM standards.)