Root Cause Analysis (RCA):

Process focused

Root cause analysis (RCA) investigages what went wrong in the process in order to prevent a future occurrence. identifies the x in the y = f(x) equation to identify those factors that lead to the process not performing to operational expectations.

Effect (Y): Belt polymer degradation (brittleness, cracking, delamination, edge fray, splice lift) with residue (flakes/dust), rising drive load, mis-tracking.
Where/When: Line/zone, shift, sanitation window, heat zones.
Magnitude: Scrap/holds, particle counts, MTBF trend, rate of belt changes.

Objective: Identify the minimum set of input factors (x) that explains > 80% of degradation rate.

Immediate Containment

Inspect belt for safety/product risk; center or stop line if flaking.
Clean below-belt catch pans and documented product-hold if contamination suspected.
Temporary mitigation: re-track, lower belt speed/heat where feasible, shield chemicals/steam overspray, replace seized idlers, neutralize residues after caustic cleaning.

2. Gemba Validation: Understand the Y = F(x) at the Gemba

Belt & Splice
Material/spec sheet, age, runtime, splice type/date, photos of damage.
Environment
Cleaning agents (name, pH, concentration, contact time, temperature), application method (foam/CIP/HP rinse/steam), dwell & rinse records.
Thermal
IR snapshots/temps at edges, drive, return run; sanitation vs production temperatures.
Mechanics
Tracking log, laser alignment report, tension readings, pulley lagging condition, idler/bearing status.
Operations
Load profile, product distribution, jam history, starts/stops, lubrication tasks on rollers.
Signals
Motor current trend, vibration on idlers, residue/particle counts per shift.
Change History
Last changes to chemicals, concentrations, sanitation SOPs, belt vendor/lot, pulley/structure repairs.

3. Fishbone

Create the fishbone then dial down the list of potenail root causes by going to the Gemba.

Materials: Belt polymer compatibility; splice adhesive/sealant; drive lagging material.
Methods: Chemical mix ratio, dwell/rinse steps, hot-HP wash sequencing; tracking/tension set method.
Machines: Misaligned pulleys, seized/worn idlers, warped frame, hot bearing near belt edge.
Manpower: Over-adjustment, PM skipped, sanitation mis-mix, new staff training gap.
Measurement: No titration logs, temp/pH not recorded, no IR baseline thresholds.
Environment: Steam/UV exposure, pooling moisture, caustic aerosols, heat from adjacent equipment.

4. 5-Whys

After the potential root causes are narrowed down, dig deep into the potential cause.

Verified: Edge cracking & blue dust after sanitation

Why #1: Edge cracking? Polymer embrittlement at edges.

Why #2: Polymer embrittlement? Repeated exposure to hot caustic + insufficient rinse.

Why #3: Exposure at edges? Mis-tracking into spray/steam cone on one side.

Why #4: Mis-tracking? Auto-tracker lag + contaminated tracking roller.

Why #5: Contamination? PM lacks “clean & spin-check tracking rollers” step.

Test: Dye test on spray cone coverage + track wander video; check tracker roller rotation post-clean.

Splice lifting 2–4 weeks after replacement

Why #1: Why splice lift? Chemical ingress undermined bond.

Why #2: Chemical ingress? Splice not sealed for caustic; incompatible adhesive.

Why#3: Wrong adhesive? Vendor specification not matched to sanitation chemistry/temperature.

Why #4: Belt specification miss? No pre-approval compatibility matrix; purchasing changed supplier.

Why #5: Governance gap? Missing ECN/QA review for belt material and adhesive changes.

Test: Lab soak of splice coupons in plant chemical at process temperature; peel/shear comparison.

Surface blistering near drive

Why #1: Blisters? Trapped chemicals heated by friction hotspot.

Why #2: Hotspot? Worn lagging + over-tension causes slip/heat.

Why $3: Over-tension? No calibrated tension method; “tighten until no slip.”

Why #4: No method? PM standard lacks numeric target; no tension gauge ownership.

Test: Tach match (belt vs pulley), thermal rise during start-up, tension gauge trial.

5) Fault Tree (trimmed)

Degradation: (Chemical exposure and Heat) ∨ (Friction heat ∧ Poor material)

Chemical exposure: (High pH ∨ Oxidizers ∨ Solvents) ∧ (High temp ∨ Long dwell ∨ Poor rinse)
Heat: (Steam ∨ Dryer proximity ∨ Friction from mis-tracking/seized idlers)
Friction heat: (Mis-tracking ∨ Over-tension ∨ Worn lagging ∨ Seized idler)
Poor material: (Wrong polymer ∨ Wrong splice adhesive ∨ No edge seal)

Use to prioritize tests that cut multiple branches at once (e.g., IR + chemical titration + tracking audit).

Verification Tests & Acceptance Criteria

Chemistry
Titration log: each batch within vendor spec (± tolerance).
Rinse pH: final rinse 6.5–7.5 (or vendor-stated neutralization).
Thermal
IR: edge ΔT vs center ≤ +5–8 °C during run; no hotspots at idlers >70–80 °C (set per belt spec).
Tracking
Track wander ≤ ±3 mm over 10 minutes steady state; no frame contact marks.
Mechanics
Idlers free-spin: ≥10–15 sec by hand, no noise; vibration pen within baseline.
Tension: measured with gauge to vendor setting (recorded).
Residue
Particle count below action limit (define per risk: e.g., ≤1 particle/10 m belt per shift in food lines).
Material
Compatibility report on file; splice coupon soak/peel ≥ vendor minimum.

Root Causes to Confirm/Eliminate (Typical)

RC-1: Mis-tracking exposes belt edge to hot caustic/steam.
RC-2: Incompatible belt polymer or splice adhesive for chemicals/temperature.
RC-3: Over-tension + worn lagging → friction heat.
RC-4: Seized/contaminated tracking/idler rollers → local heating + wander.
RC-5: Sanitation mix/dwell/rinse out of spec (no titration, short rinse).
RC-6: UV/ozone exposure (if belts stored improperly).
RC-7: Governance gap: supplier change without QA compatibility review.

Corrective & Preventive Actions (CAPA)

Corrective (near-term)

Re-track; replace/clean tracking rollers and any seized idlers.
Restore tension to measured spec; replace worn lagging.
Install edge shields or re-aim nozzles to keep sprays off belt edges.
Replace degraded belt with verified compatible material; reseal splice edges.

Preventive (systemic)

Compatibility Matrix: Belt/adhesive vs all chemicals, pH, temp; QA signoff required.
Sanitation SOP: Titration per batch, dwell & rinse timers, temp caps, neutralization step.
Tracking PM: Clean/inspect tracking rollers; laser audit quarterly; tracker response test.
Measured Tensioning: Tension gauges + target table; no “tighten until no slip.”
IR Routes: Add IR checkpoints (edges, drive, return, known hotspots) post-clean and mid-shift.
Change Control (ECN): Any belt/adhesive/vendor/chemical change requires QA/Engineering approval.
Storage/Handling: Belts stored cool, dark, flat; FIFO by lot; splice kits within shelf life.
Training: Operators—signs of mis-tracking & immediate call; Sanitation—mix/rinse verification; Maint—tension/track with measurement.

9) Controls & Monitoring (Sustaining)

Leading KPIs:
% sanitation batches titrated in spec; % IR routes completed; track wander rate; idler free-spin pass rate.
Lagging KPIs:
Belt MTBF, splice failure rate, residue findings, unplanned downtime due to belt.
Control Plan:
Weekly: tracking audit + idler spot-checks;
Monthly: IR trend report & CAPA review;
Quarterly: laser alignment + ECN audit on materials/chemicals.

10) Roles & Escalation (RCA-Specific)

Operator: Capture symptoms (noise, drift, residue), tag; verify post-fix tracking window.
Maintenance: Perform measured tensioning, tracker cleaning, idler replacements; log proof (photos/values).
Engineer/ Reliability: Run IR/chemistry/tracking studies; own compatibility matrix; approve design/SOP changes.
Quality: Own titration & rinse verification, residue CCP/PRP, product-hold decisions; audit ECN compliance.
Steering/CI: Review KPIs monthly; remove systemic barriers (tools, gauges, training time).

11) DOE / Rapid Experiments (if still ambiguous)

2×2 (Chem Temp × Rinse Time): Validate material margin on scrap coupons.
Tracker Lag Test: Step-change tracker responsiveness and measure wander amplitude.
Tension Sweep: Map current draw & IR vs tension setpoints to find minimum-heat region.

Deliverables (ready to print/attach)

One-page Problem Statement + Fault Tree.
IR photo sheet (before/after).
Sanitation titration & rinse log excerpt.
Tracking audit (laser) + tension records.
Compatibility matrix signoff.
CAPA list with owners/dates + control plan.

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Failure Description:

Fingerprint

GO / No Go