When a machine stops or produces poor quality, follow this systematic approach:
Observe — What exactly is wrong? When did it start?
Check basics — Power, air pressure, material supply
Review PLC — Check error codes and alarm history
Inspect — Look at the problem area closely
Isolate — Run machine slowly, test one component at a time
Fix — Address the root cause, not just the symptom
Document — Record the issue and solution for future reference
Tuber Machine Problems
Paper Break During Tubing
Cause
Diagnosis
Solution
Paper tension too high
Paper snaps at guide rollers
Reduce tension setting by 10–20%
Paper splice (joint)
Break at splice location
Remove bad splice, re-thread
Worn guide rollers
Paper cuts at roller edge
Polish or replace roller
Paper roll defect
Break at same position each revolution
Change paper roll
Humidity damage
Paper feels soft, tears easily
Replace roll, check storage conditions
Crooked/Uneven Tubes
Cause
Diagnosis
Solution
Paper misalignment
Tube edges unequal on both sides
Adjust guide rollers and paper alignment
Uneven tension
One side tighter than other
Balance tension on both sides
Worn mandrel
Tube shape distorted
Replace or repair forming mandrel
Paper roll tracking
Roll not centered on shaft
Recenter roll, check brake alignment
Weak Tube Seam
Cause
Diagnosis
Solution
Glue temperature too low
Bond peels easily
Increase temp by 5–10°C
Glue temperature too high
Charred adhesive, stringing
Decrease temp, check nozzle cleanliness
Insufficient glue
Visible gaps in seam
Increase glue flow rate
Wrong adhesive
Bond fails under stress
Verify adhesive type matches paper
Nozzle clogged
Uneven glue application
Clean or replace nozzle
Bottomer Machine Problems
Bottom Seal Failure (Bag Opens Under Load)
Cause
Diagnosis
Solution
Weak adhesive bond
Bottom peels open
Check glue coverage, temp, and type
Incorrect fold geometry
Uneven fold pattern
Adjust folding mechanism alignment
Paper too thick/thin
Fold doesn’t lay flat
Verify paper GSM matches specification
Press roller pressure low
Bond not compressed
Increase roller pressure
Speed too high
Insufficient bonding time
Reduce bottomer speed
Valve Problems
Cause
Diagnosis
Solution
Valve too tight
Filling nozzle won’t enter
Adjust valve cutter to wider opening
Valve too loose
Cement leaks from valve
Adjust cutter to smaller opening
Valve tears during filling
Paper tears at valve edge
Add reinforcement patch, use stronger paper
Valve misaligned
Not centered on bag end
Adjust valve cutter position
Feeding Problems (Tubes Not Feeding)
Cause
Diagnosis
Solution
Suction cups worn
Tubes not picked up
Replace suction cups
Air pressure low
Weak suction
Check compressor, fix leaks
Tubes stuck together
Static cling or humidity
Separate tubes, reduce humidity
Magazine misaligned
Tubes jammed in feeder
Adjust magazine guides
Circular Loom Problems
Weft Tape Breakage
Cause
Diagnosis
Solution
Tape quality poor
Breaks at thin spots
Check tape extrusion quality
Shuttle tip worn
Cuts tape during insertion
Replace shuttle tips
Tension too high
Breaks at high-tension points
Reduce weft tape tension
Reed damage
Tape catches on damaged reed
Inspect and repair/replace reed
Speed too high
Breakage rate increases at high RPM
Reduce loom speed
Fabric Defects
Defect
Cause
Solution
Missing weft (holes)
Shuttle malfunction
Check shuttle timing, spring tension
Loose weave
Incorrect reed setting
Adjust reed position for tighter weave
Uneven width
Tension imbalance
Balance warp tape tension across creel
Edge curl
Incorrect take-up tension
Adjust take-up roller pressure
Lines/streaks
Damaged or dirty shuttle
Clean or replace shuttle
Printing Machine Problems
Poor Print Quality
Issue
Cause
Solution
Blurry print
Plate wear or wrong pressure
Replace plate, adjust impression
Color mismatch
Wrong ink formula or density
Remix ink, check viscosity
Registration error
Misaligned printing stations
Realign stations, check gear mesh
Ink not drying
Insufficient drying heat/time
Increase dryer temperature or slow speed
Ink rubbing off
Wrong ink type or no overcoat
Use correct ink, add overprint varnish
Electrical and PLC Issues
Common PLC Error Codes
Alarm
Meaning
Action
E001
Emergency stop pressed
Reset e-stop, check safety
E010
Motor overload
Check motor, reduce load, check belt
E020
Temperature out of range
Check heating element, thermocouple
E030
Sensor timeout
Clean or replace sensor
E040
Communication error
Check wiring, restart PLC
E050
Over-speed alarm
Check encoder, reduce speed setting
Note: Error codes vary by manufacturer. Always refer to your machine’s manual.
Electrical Safety Rules
ALWAYS lock out/tag out before electrical work
Only trained electricians should access electrical panels
Never bypass safety interlocks
Keep electrical panels closed during production
Test voltage before touching any electrical components
When to Call for Help
Call the manufacturer or a specialist when:
PLC program is corrupted or needs reprogramming
Servo motor or drive fails
Structural damage to machine frame
Problem persists after all troubleshooting steps
Safety system malfunction
Frequently Asked Questions
What’s the most common machine issue?
Paper/tape breaks and sensor malfunctions account for about 50% of all machine stoppages. Regular material quality checks and sensor cleaning prevent most of these.
How can I reduce troubleshooting time?
Document every issue and solution in a maintenance logbook. After 3–6 months, you’ll have a custom troubleshooting guide for your specific machines. 80% of problems are repeat issues.
Should I keep the Chinese technician’s phone number?
Absolutely. Build a relationship with the manufacturer’s service department. Most Chinese suppliers provide remote troubleshooting via WeChat video call, which can solve 60–70% of issues without an on-site visit.