Common troubleshooting of rubber/silicone extrusion lines: solutions from blockage to dimensional deviation

Rubber and silicone extrusion production lines may encounter various problems during operation, such as blockage, dimensional deviation, surface defects, etc. These problems directly affect production efficiency and product quality. Understanding common causes of failures and finding solutions in a timely manner can help operators quickly troubleshoot problems and ensure stable operation of the production line.

1. Extruder blockage (bridging/breaking)

Possible causes

Raw material problems:

Poor fluidity of the rubber compound (such as too high hardness, moisture or impurities).

Uneven feeding (different particle sizes or agglomeration).

Equipment problems:

Improper design of the feeding port (such as too small feeding angle).

Screw wear or mismatched compression ratio.

Improper temperature setting (too low leads to poor plasticization of the rubber compound).

Solutions

Optimize raw materials:

Use premixed rubber to ensure consistent fluidity.

Dry the rubber compound (silicone needs to control humidity <0.1%). Adjust equipment:

Check the screw wear and replace if necessary.

Increase the temperature of the feeding section (usually 70~90℃ for silicone and 100~120℃ for rubber).

Add a forced feeding device (such as a side feeder).

2. Unstable size of extruded product (too large/too small)

Possible reasons

Extrusion speed does not match traction speed:

Too fast traction → product becomes thinner.

Too slow traction → product becomes thicker.

Temperature fluctuation:

Head temperature is too high → melt expands, size is too large.

Temperature is too low → poor plasticization, uneven size.

Mold problem:

Die wear or unreasonable design (such as unbalanced flow channel).

Solution

Optimize process parameters:

Adjust traction speed to synchronize with extrusion speed (laser diameter gauge can be installed for real-time monitoring).

Stabilize the temperature of each section (usually the die temperature of silicone extrusion is 160~200℃, and rubber is 140~180℃).

Check the mold:

Measure the die size regularly and replace it when it is severely worn.

Use multi-hole adjustment mold (suitable for products with complex cross-sections).

3. Surface defects (bubbles, roughness, cracks)

Possible reasons

Bubbles:

The rubber contains water or volatiles (silicone is easy to absorb moisture).

Poor exhaust (vacuum extruder is not turned on or vacuum is insufficient).

Rough surface:

Extrusion temperature is too low → incomplete plasticization.

Screw speed is too high → shear overheating leads to degradation.

Cracks:

Cooling too fast (such as low temperature of cold water tank).

Rubber compound formulation problem (such as improper vulcanization system).

Solution

Raw material processing:

Silicone needs to be dried in advance (100℃×2 hours).

Strengthen rubber discharge during rubber mixing (avoid entrainment of air). Adjust the process:

Increase the temperature of the plasticizing section (silicone is recommended to be 90~120℃).

Reduce the screw speed (generally controlled at 20~60 rpm).

Use gradient cooling (warm water first and then cold water).

Other common problems

Preventive maintenance recommendations

• Daily inspection: clean the feed port and check whether the heating ring is damaged.
• Weekly maintenance: lubricate the screw bearing and check the tightness of the drive belt.
• Monthly maintenance: calibrate the temperature control system and check the mold wear.