Troubleshooting / Pipe extrusion line

Pipe Extrusion Line Troubleshooting

The most common pipe extrusion line problems on the plant floor, with the likely causes and the fix for each. Part of the OEE Lab troubleshooting directory.

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Problems on this page:

Wall thickness out of toleranceOutside diameter or ovality out of toleranceSurface defects on the pipeCutter or saw problemsPrinting faults on the pipeHaul-off slippingLong size changesMaterial feed problems

Wall thickness out of tolerance

Hits OEE: Quality

Symptoms: The ultrasonic gauge or hand measurements show thin or thick walls.

Die not centred
Centre the die using the wall thickness readings around the pipe.
Melt temperature uneven around the die
Check the die heater zones.
Haul-off speed varying
Check the haul-off speed control and the grip of the caterpillar tracks.
Extruder output varying
Check the material feed, the screw speed and the melt pressure.

Prevention: Wall thickness measured around the circumference continuously or at set intervals.

Outside diameter or ovality out of tolerance

Hits OEE: Quality

Symptoms: Pipe diameter or roundness fails the specification.

Vacuum sizing tank vacuum unstable
Check the vacuum pump and the tank seals.
Calibrator sleeve worn
Check the calibrator sleeve diameter.
Cooling water too warm or uneven
Check the cooling water temperature and spray nozzles.
Pipe sagging before it has set
Check the support rollers and cooling length.

Prevention: Diameter and ovality measured at set intervals.

Surface defects on the pipe

Hits OEE: Quality

Symptoms: Lines, roughness or bubbles show on the pipe surface.

Moisture in the material
Check the dryer where the material needs drying.
Die lines from damage or deposits
Clean and polish the die land.
Melt temperature wrong for the material
Check the barrel and die temperatures against the recipe.
Contamination in the material or regrind
Check the material and the regrind ratio.

Prevention: Pipe surface inspected continuously.

Cutter or saw problems

Hits OEE: Availability

Symptoms: Cuts are uneven or angled, or the saw stops the line.

Blade dull or damaged
Replace the blade on the interval set for the material.
Cutter carriage not synchronised with the pipe
Check the carriage speed matching.
Pipe clamp slipping
Check the clamp pads and pressure.
Chip extraction not working
Check the extraction so chips do not jam the saw.

Prevention: Cut quality checked on samples.

Printing faults on the pipe

Hits OEE: Quality

Symptoms: Marking on the pipe is missing, smudged or at the wrong spacing.

Encoder not following line speed
Check the encoder wheel and its contact with the pipe.
Ink not suited to the material
Check the ink for the pipe material.
Pipe surface wet at the printer
Dry the surface with air wipes before printing.
Print head dirty
Clean the print head as the maker specifies.

Prevention: Marking checked at each length.

Haul-off slipping

Hits OEE: Availability

Symptoms: The haul-off tracks slip on the pipe, and wall thickness swings.

Track pads worn
Replace worn pads.
Contact pressure too low
Check the clamping pressure for the pipe size.
Water on the pipe at the haul-off
Dry the pipe before the haul-off.
Upper and lower track speeds different
Check the speed matching of the tracks.

Prevention: Track pads checked weekly.

Long size changes

Hits OEE: Performance

Symptoms: Changing pipe size takes long and makes a lot of scrap.

Die, calibrator and sizing parts not ready
Stage and check the tooling before the change.
Settings not stored per size
Store temperatures, speeds and vacuum settings per size.
Start-up done by trial
Write a start-up sequence with set steps.
Vacuum tank parts changed one by one
Prepare the tank inserts as a set.

Prevention: Size change time and scrap recorded.

Material feed problems

Hits OEE: Availability

Symptoms: The hopper runs empty or the feed is uneven.

Vacuum loader fault
Check the loader filter and its vacuum.
Dryer running empty
Check the material level in the dryer.
Material bridging in the hopper
Check the hopper design and the material flow.
Gravimetric blender error
Check the blender load cells and settings.

Prevention: Feed alarms recorded.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: extruder · resin dryer · vacuum pump · chiller · cable extrusion line

Stop the same fault coming back

Recurring pipe extrusion line stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

Book a Fabrico demo
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Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary

Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover