Use observable evidence to separate feeder, press/die, material and upstream-line causes—then isolate the equipment before any intrusive inspection.
Three troubleshooting boundaries
Read alarms and indicators, confirm the job/recipe, inspect visible conditions from outside guarding and preserve samples. No access to danger zones.
Place the system in its approved stopped state when production cannot continue normally. Prevent an automatic or remote restart while the issue is evaluated.
Apply the site’s energy-control procedure, dissipate or restrain stored energy, verify isolation and then inspect components under the machine manual.
The correct boundary depends on the machine design, safeguarding, local procedure and the task. A stopped HMI does not prove that electrical, pneumatic, hydraulic, gravity, spring or coil energy is absent.
Capture evidence before changing anything
Changing several settings before recording the condition destroys useful evidence and can introduce a second fault. Restore or alter a parameter only under the approved setup procedure and record the before/after value.
Symptom router: what to observe and when to isolate
| Symptom | Safe observations | Stop / isolate trigger | Qualified inspection path |
|---|---|---|---|
| Feeder will not start | Read the complete HMI message. Confirm the selected recipe, run mode, production counter state, press-ready signal and visible guard/E-stop indicators. | Stop Do not bypass an interlock or force an output to obtain motion. | Using drawings and I/O diagnostics, verify the permissive chain, command signal, safety circuit status and controller/drive faults. |
| Short feed or variable pitch | Compare commanded length with a defined measurement at the strip/part. Note whether error changes with speed, material lot or die operation. | Isolate if checking rolls, encoder/coupling, transmission or clamping components. | Separate command/calibration, traction, pilot action, strip pull-back, encoder feedback and measurement-system contributions. |
| Strip tracks sideways | From a safe position, observe coil centering, guide contact, loop position, edge condition and where deviation first appears. | Stop if the strip approaches a guard, sensor, die edge or pinch point, or begins to buckle. | After isolation, inspect line center, pass line, guide condition, roll parallelism, coil telescoping and material camber. |
| Strip buckles or arches | Note the buckle location, loop state, press phase and whether the feeder completed its command. | Stop before the strip enters a hazard zone or contacts tooling/guards. | Review pass line, die-entry resistance, strip guides, feed acceleration, loop control, pilot timing and carrier stiffness. |
| Pilot-release mismatch | Preserve the affected progression. Review the alarm/event trend and approved timing values; do not reach into the die. | Isolate for any inspection of the die, release mechanism, valve, cable or sensor. | Verify press position reference, release command, pneumatic/electrical response, pilot condition, strip lift and feed completion. |
| Surface scratches or repeating marks | Find the first location where the mark appears and its repeat distance. Check the material before it enters the line. | Isolate before cleaning or inspecting rolls and guides. Never wipe moving rolls or strip. | Inspect contact surfaces, embedded debris, roll condition, guide clearance, pressure setting and material/coating compatibility. |
| Abnormal noise, impact or vibration | Stop and record when/where it occurred; preserve alarm history. Do not run again merely to reproduce a severe noise. | Immediate assessment Unexpected grinding, impact or visible damage requires isolation. | Inspect drive, bearings, belts/gears, fasteners, roll contact, foreign objects and press/die interference under the service procedure. |
| Feeder/press timing alarm | Record press speed, feed-start/end signals and whether the fault appears after a speed or recipe change. | Stop repeated timing faults before a misfeed can damage the die. | Validate the available feed window, acceleration profile, signal integrity, press position reference and completion interlock. |
Diagnosing pitch variation without guessing
“The feeder is inaccurate” is a symptom description, not a root cause. Define the error first:
- Is the commanded length different from the encoder-reported length?
- Does the strip move the commanded length at the feeder exit but the pitch changes after pilot entry or forming?
- Is the error constant, random, cyclic, speed-dependent or material-lot-dependent?
- Was pitch measured at a pilot hole, cut edge, part feature or feeder exit—and with what device and sample size?
A constant proportional error may point toward recipe units, calibration or effective roll diameter. Intermittent short feed can involve traction, contamination, clamping, excessive strip resistance or timing. Variation that appears only with the die operating can involve pilots, strip lift, pull-back, die entry or press/feed coordination. These are diagnostic directions, not permission to adjust the machine outside its manual.
Safe isolation and restart principles
Follow the site procedure and the manuals for the entire integrated line. A typical assessment considers the press, feeder, straightener, uncoiler, loop controls and auxiliary equipment—not just the component where the symptom appeared.
- Notify affected personnel and bring the system to the approved stopped condition.
- Identify every relevant source of electrical, pneumatic, hydraulic, mechanical, gravity, spring and stored coil energy.
- Apply lockout/tagout or the site’s legally compliant energy-control procedure.
- Block, restrain, bleed, discharge or otherwise control stored energy as specified.
- Verify isolation using the approved method before work begins.
- After repair, inspect the work area, restore guards, account for personnel/tools and follow the controlled restart procedure.
- Validate at defined conditions and document the result before returning to normal production.
Information to send HENLI or your service team
For pitch-specific diagnosis, use the feed pitch accuracy guide. For equipment selection and capability boundaries, see how to choose a stamping press feeder.
Frequently asked questions
Can I clean feeder rolls while jogging slowly?
No. Moving rolls and strip create in-running nip, entanglement and cutting hazards. Stop and isolate the equipment according to the site procedure and machine manual before cleaning requires access to the rolls.
Should I increase air pressure when the strip slips?
Not as a blind correction. First compare supply and regulated pressure with the approved specification and diagnose contamination, roll condition, strip resistance, material surface, clamping response and timing. Unauthorized pressure changes can damage stock or equipment.
Why will the feeder not release for the pilots?
Possible contributors include the press position reference, release command/timing, permissives, valve or actuator response, air supply, wiring, pilot condition and feeder mechanism. Preserve the strip, stop repeated misfeeds and isolate before component inspection.
What if the feeder display shows the correct length but the part pitch is wrong?
Measure where the error first appears. Die pilots, strip lift, carrier deformation, pull-back, slip, press timing and the measurement system can change the result after the feeder reports completion.
When should I call service?
Call qualified service when the fault involves a safety circuit, guarding, repeated misfeed, drive/controller alarm, damaged mechanical component, abnormal noise, loss of calibration, or any inspection/repair beyond the training and authorization of site personnel.
Send evidence, not a guessed root cause
Provide the exact alarm, machine identity, recipe, material, speed, retained strip/parts and the last known good condition. HENLI can help define the next safe diagnostic step for supported equipment.
Safety note: This guide supports initial classification only. It does not replace the equipment manuals, site risk assessment, safeguarding, training, lockout/tagout procedure or work authorization. Local legal requirements and the approved procedure govern.
