Problems on this page:
Sheet gauge varying across the width
Hits OEE: Quality
Symptoms: The calendered sheet or coated fabric is thicker at the edges or the centre.
Roll crown or bending not matched to the compound and width
Check the roll bending or crossing settings for the product.
Roll temperatures uneven across the face
Check the roll temperature control and the rotary joints.
Feed bank uneven across the nip
Keep an even rolling bank across the nip.
Gauge measurement out of calibration
Check the gauge against hand measurements.
Prevention: Cross-direction gauge profile recorded per run.
Gauge varying along the length
Hits OEE: Quality
Symptoms: The gauge drifts or pulses along the sheet.
Feed rate from the mill or extruder varying
Check the feed strip and the bank size control.
Roll speed control unstable
Check the roll drives for speed variation.
Bearing play
Check the roll bearings for play under load.
Compound temperature varying
Check the temperature of the feed strip from the warming mill or extruder.
Prevention: Gauge trended along the run.
Blisters or air in the sheet
Hits OEE: Quality
Symptoms: Air bubbles or blisters appear in the calendered sheet.
Rolling bank too small to push air out
Keep a bank size large enough to work the air out of the compound.
Moisture or volatiles in the compound
Check the compound moisture and the storage of raw materials.
Roll temperature too high, making volatiles boil
Check the roll temperatures against the recipe.
Line speed too high for the compound
Reduce the speed and compare.
Prevention: Sheet inspected continuously for blisters.
Fabric coating faults
Hits OEE: Quality
Symptoms: Rubber does not penetrate or stick well to the fabric on coating runs.
Fabric tension uneven or too high
Check the let-off tension across the fabric width.
Fabric moisture too high
Dry the fabric before coating as the specification sets.
Nip pressure too low for penetration
Check the nip setting for the fabric and compound.
Roll temperatures wrong for the compound
Set the roll temperatures for the compound and fabric as the coating recipe gives.
Prevention: Adhesion tested on samples from each run.
Roll surface damage
Hits OEE: Availability
Symptoms: Marks or scratches on the rolls print into the sheet.
Foreign objects passing through the nip
Check the feed for metal and add a metal detector on the feed strip.
Hard tools used for cleaning
Clean rolls only with the soft tools and materials the maker allows.
Corrosion during stops
Protect the roll surfaces during long stops.
Doctor blade damaged
Check the doctor blade edge and its pressure.
Prevention: Roll surfaces inspected at each stop.
Safety stop faults
Hits OEE: Availability
Symptoms: The trip wire or emergency stop does not stop the rolls as it should.
Trip wire slack or misrouted
Adjust the trip wire tension and check its route along the nip.
Trip switch faulty
Replace the switch and test the stop.
Brake worn
Have the brake serviced; a calender nip that does not stop fast enough is a serious hazard.
Stopping test not done
Test the stopping distance at the interval the site sets.
Prevention: Trip wire and stops tested at each shift start.
Wind-up faults
Hits OEE: Availability
Symptoms: The wind-up wrinkles the sheet, mis-tracks the liner or stops.
Wind-up tension wrong
Set the tension for the sheet thickness and width.
Liner feed not tracking
Check the liner let-off and its guiding.
Cores damaged or out of round
Check the cores before loading.
Wind-up drive fault
Check the drive and its speed matching to the calender.
Prevention: Wound rolls checked at each change.
Long changeovers
Hits OEE: Performance
Symptoms: Changing product or gauge takes long and produces a lot of scrap.
Settings not stored per product
Store the roll temperatures, nip and bending settings per product.
Cleaning between compounds
Plan the run order to reduce cleaning between compounds and colours.
Rolls need time to reach the new temperature
Start the temperature change before the current run ends where possible.
No written changeover sequence
Write the sequence and record the time and scrap of each change.
Prevention: Changeover time and scrap recorded.
Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.
Related equipment guides: two roll mill · internal mixer · laminator · slitter rewinder · chiller
Stop the same fault coming back
Recurring calender 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