Why Equipment Reliability Is a Lean Prerequisite
Every lean tool depends on equipment reliability. One-piece flow fails if the machine in the cell breaks down every 4 hours. Pull systems fail if the producing machine cannot respond to the kanban signal reliably. Heijunka fails if changeovers are unreliable and first-article quality varies.
TPM creates the equipment stability that makes all other lean improvements possible. Without it, lean tools are built on an unstable foundation.
OEE: The Universal Metric
Planned time: 480 min (8-hour shift)
| Factor | Calculation | Result |
|---|---|---|
| Availability | (480 – 60 min downtime) ÷ 480 | 87.5% |
| Performance | (380 parts × 1 min ideal cycle) ÷ 420 min run time | 90.5% |
| Quality | (380 – 12 defective) ÷ 380 | 96.8% |
| OEE | 87.5% × 90.5% × 96.8% | 76.6% |
Interpretation: This machine is producing good parts only 76.6% of the time it is available. The 23.4% gap represents: 12.5% availability loss (breakdowns + changeover), 9.5% performance loss (minor stops + slow cycles), and 3.2% quality loss (scrap + rework). Each loss category directs improvement focus to a specific TPM pillar.
The Six Big Losses
| Loss | OEE Factor | Example | TPM Countermeasure |
|---|---|---|---|
| 1. Breakdowns | Availability | Spindle bearing failure, hydraulic leak | Autonomous maintenance (early detection), planned PM schedules |
| 2. Setup/Adjustment | Availability | Tool change, program load, first-article run | SMED, standardized setups, pre-staged tooling |
| 3. Minor Stops | Performance | Chip jam, sensor trip, material feed hesitation | Root cause analysis of recurring minor stops, poka-yoke |
| 4. Reduced Speed | Performance | Machine running at 80% of rated speed “because it vibrates at full speed” | Restore design conditions, replace worn components |
| 5. Defects | Quality | Out-of-tolerance parts requiring rework or scrap | Process capability study, tool wear monitoring, SPC |
| 6. Startup Losses | Quality | First 3 parts after changeover are scrap while dialing in | Standardize setup parameters, SMED Stage 3 |
Autonomous Maintenance: The 7 Steps
Autonomous maintenance (Jishu Hozen) transfers basic equipment care from the maintenance department to the operators who use the equipment daily. The 7 steps progress from basic cleaning to self-management:
Step 1: Initial Cleaning
Deep clean the machine while inspecting every surface. Tag every abnormality found (leaks, cracks, loose bolts, missing covers). This is cleaning as inspection, not cleaning as housekeeping. Typical first cleaning finds 50–200 abnormalities per machine.
Step 2: Eliminate Contamination Sources
Address the root causes of dirt, leaks, and hard-to-access areas. If the machine gets dirty because the coolant guard is missing, install the guard. If it is hard to inspect because the panel is bolted shut, add a window or quick-release.
Step 3: Establish Cleaning and Inspection Standards
Create a visual checklist: what to clean, what to inspect, how often, and what “normal” looks like. Post it at the machine with photos. Target: 5–10 minute daily check.
Step 4: General Inspection Training
Train operators to inspect beyond cleaning: bearing sound, vibration feel, temperature changes, oil quality. The operator becomes the first line of defense against equipment degradation.
Step 5: Autonomous Inspection
Operators perform inspections independently using the standards from Steps 3–4. Maintenance provides support and training, but the daily checks are owned by operations.
Step 6: Standardize and Organize
Integrate autonomous maintenance into standard work. Cleaning, inspection, and lubrication become part of the operator’s daily routine, not a separate activity.
Step 7: Self-Management
Operators take ownership of their equipment’s condition. They initiate improvement activities, track their own OEE, and work with maintenance on planned upgrades. The distinction between “operator” and “maintainer” blurs.
💡 Start with One Machine
Do not attempt to implement autonomous maintenance across the entire factory simultaneously. Pick the constraint machine (highest OEE impact). Take it through Steps 1–3 in 4–6 weeks. Demonstrate results. Then expand to the next machine. A successful pilot builds credibility; a failed factory-wide rollout builds cynicism.
Planned Maintenance: The PM Program
Autonomous maintenance handles daily care. Planned maintenance handles scheduled interventions based on equipment condition and manufacturer recommendations. The progression:
| Level | Approach | Trigger |
|---|---|---|
| Reactive | Fix it when it breaks | Failure |
| Preventive (PM) | Replace/inspect on a time or usage schedule | Calendar or cycle count |
| Predictive (PdM) | Monitor condition and intervene when degradation is detected | Vibration analysis, oil analysis, thermal imaging |
| Proactive | Redesign the equipment or process to eliminate the failure mode | Root cause elimination |
Most factories are stuck between reactive and basic PM. The goal is to move the majority of maintenance activity to PM and PdM, reducing reactive (unplanned) maintenance to less than 10% of total maintenance hours.
🎯 The Bottom Line
TPM creates the equipment reliability that every lean tool requires. OEE measures effectiveness across three dimensions (Availability × Performance × Quality) and the six big losses tell you exactly where to focus. Autonomous maintenance (7 steps) puts operators in charge of daily equipment care. Planned maintenance prevents failures before they occur. Start with OEE measurement on the constraint machine, implement autonomous maintenance Steps 1–3, and build from there. Next: A3 Problem Solving — the structured thinking tool that drives root cause elimination for the problems TPM uncovers.
Stop reading, start modeling
Model your process flow, run simulations, optimize staffing with TOC math, and test your knowledge with 107 interactive checks — all in one platform.