Equipment Management Series Issue 1: Autonomous Maintenance and Planned Maintenance — From "Fix When Broken" to "Equipment Self-Care"
Abstract: Equipment failures causing production line stoppages, maintenance teams running around like firefighters, and the same machine breaking down repeatedly — many companies' equipment management is still stuck in a "firefighting" mode. Autonomous Maintenance (AM) and Planned Maintenance (PM) are the foundations of TPM and lean manufacturing, involving operators in daily inspections and specialized maintenance teams in preventive maintenance to nip failures in the bud. This article systematically explains the division of labor in AM/PM, the seven-step autonomous maintenance method, and key points in planning PM.
1. A Scenario: The Busier the Maintenance, the More Frequent the Failures
A certain injection molding workshop has three production lines, and the equipment department has only four maintenance workers. The team leader complains: "When a machine breaks down, it stops. The maintenance team comes to disassemble and repair it, and it takes a couple of hours to get it running again — next week, the same machine breaks down again." The head of the equipment department counters: "There aren't enough people, so we can only focus on key equipment."
The workshop supervisor reviewed the data: over the past six months, unplanned downtime accounted for 68% of total downtime, with 40% of the failures related to inadequate lubrication, tightening, and cleaning — not "major issues," but "minor oversights" accumulating.
This is a typical Breakdown Maintenance model: equipment is ignored until it fails, and then it is urgently repaired. The cost includes production line stoppages, overtime, urgent spare parts purchases, quality fluctuations, and maintenance personnel constantly dealing with recurring issues that were not fully resolved last time.
Autonomous Maintenance + Planned Maintenance is the first step out of this model.
2. Four Levels of Equipment Maintenance Evolution
| Level | Mode | Characteristics | Typical Results |
|---|---|---|---|
| L0 | Fix When Broken | No prevention | Unpredictable downtime |
| L1 | Planned Maintenance (PM) | Regular maintenance | Reduced failures, still dependent on specialized teams |
| L2 | Autonomous Maintenance (AM) | Daily inspections by operators | Early detection, responsibility delegation |
| L3 | Predictive Maintenance (PdM) | Data/status monitoring | Replace components based on condition, see 12.2.2 |
This series' first issue focuses on L1 + L2 — the majority of manufacturing companies should first solidify this foundation before discussing predictive maintenance.
3. Autonomous Maintenance (AM): Why Operators Should Manage Equipment
Autonomous Maintenance is not about having operators fix complex failures, but rather making them responsible for daily inspections, cleaning, lubrication, tightening, and simple adjustments — "I am responsible for my equipment."
1. Value
- Early Detection: Operators are the first to notice unusual sounds, odors, oil leaks, and loose parts.
- Reducing Minor Downtime: 5 minutes of tightening vs. 2 hours of disassembly.
- Cultivating Equipment Awareness: Shifting from "I only care about output" to "equipment condition is also my KPI."
- Liberating Specialized Maintenance: Maintenance workers can move from "greasing" to "root cause analysis and design improvement."
2. Relationship with Quality
Equipment condition directly affects process capability — mold wear can cause dimensional drift, fixture loosening can lead to poor positioning, and insufficient cooling can result in deformation. AM is the manifestation of source quality control in the equipment dimension, consistent with 5.3.3 "Do It Right the First Time."
3. Seven-Step Autonomous Maintenance Method (Classic TPM Path)
| Step | Name | Key Points |
|---|---|---|
| 1 | Initial Cleaning | Thorough cleaning to expose hidden issues (oil leaks, cracks) |
| 2 | Elimination of Contamination Sources | Prevent recontamination (covers, recycling, process improvements) |
| 3 | Establish Lubrication Standards | Diagrams showing lubrication points, grease types, cycles, and quantities |
| 4 | Tightening and Calibration | Bolt torque, belt tension, baseline inspections |
| 5 | Inspections and Visual Management | Inspection forms, color codes, abnormal condition tags |
| 6 | Standardization | AM standard work instructions, training, audits |
| 7 | Autonomous Management | Continuous improvement, team activities, case sharing |
Key to Implementation: Each step must have standards (images + values) and audits; it cannot be reduced to just "cleaning."
4. Planned Maintenance (PM): What the Specialized Teams Do
Planned Maintenance is led by the equipment/engineering department and involves preventive work based on time or operational volume.
1. Common Types of PM
| Type | Example |
|---|---|
| Regular Lubrication | Weekly/monthly/operational hours |
| Regular Replacement | Filters, seals, wear parts |
| Regular Inspection | Precision, electrical insulation, safety devices |
| Regular Overhaul | Major repairs, refurbishment, precision restoration |
2. Four Elements of PM Planning
① List of Objects — Key equipment classification (A/B/C), with the most comprehensive PM projects for Class A equipment.
② Work Standards — SOPs for each PM task: steps, tools, spare parts, labor hours, acceptance criteria.
③ Schedule Planning — Coordinate with production plans to avoid conflicts with peak delivery periods; utilize planned downtime windows.
④ Effect Verification — Track failure rates, MTBF (Mean Time Between Failures), and MTTR (Mean Time To Repair) after PM.
3. Division of Labor Between AM and PM
| Dimension | Autonomous Maintenance (AM) | Planned Maintenance (PM) |
|---|---|---|
| Executor | Operators/Team Leaders | Equipment Engineers/Specialized Maintenance |
| Frequency | Per shift/daily | Weekly/monthly/quarterly/annually |
| Content | Cleaning, inspections, lubrication, tightening | Deep maintenance, component replacement, precision adjustment |
| Records | Inspection forms, abnormal reports | PM work orders, spare parts consumption |
Interface: Abnormalities detected by AM → Fill out equipment abnormality reports → PM/maintenance teams receive orders → Feedback to operators after closure.
5. Key Indicators: Speaking with Data
Equipment maintenance should not only focus on "how many times it was repaired," but also track the following indicators:
| Indicator | Meaning | Purpose |
|---|---|---|
| MTBF | Mean Time Between Failures | Measure whether reliability has improved |
| MTTR | Mean Time To Repair | Measure response and repair capability |
| PM Completion Rate | Proportion of planned PM tasks completed on time | Measure PM execution |
| AM Inspection Compliance Rate | Proportion of inspection forms completed on time and to standard | Measure AM implementation |
| Recurrent Failure Rate | Proportion of the same type of failure recurring on the same equipment | Measure whether issues are fully resolved |
These indicators are directly related to the downtime and adjustment downtime losses in OEE (7.3.1, see Lean Manufacturing Series Issue 3) — when AM/PM are done well, the time efficiency rate of OEE naturally improves.
6. Common Misconceptions
Misconception 1: Autonomous Maintenance = Reducing Maintenance Workers. Incorrect. AM is about optimizing roles, not downsizing; specialized teams should focus on improvements and complex failures.
Misconception 2: PM is Scheduled on the Calendar, Regardless of Production. Incorrect. PM must be coordinated with production plans; otherwise, it will either be skipped or cause complaints.
Misconception 3: Inspection Forms Filled with "Normal" as a Formality. Incorrect. Inspections without abnormalities should still undergo random audits; filling all forms as "normal" often indicates ineffective inspections.
Misconception 4: Maintenance Without Root Cause Analysis. When the same failure occurs repeatedly, root cause analysis (5Why, fishbone diagram) should be initiated, and necessary design or spare part specifications should be modified.
7. Summary
Autonomous Maintenance and Planned Maintenance are the foundation of equipment management — making operators the first line of defense and shifting specialized maintenance from "firefighting" to "fire prevention."
In three sentences: Operators manage daily, specialized teams manage according to plans, and abnormalities are closed-loop managed. After solidifying this foundation, the next issue will discuss SMED (Single Minute Exchange of Die) — how to transform mold and line changes from "black holes of equipment efficiency" into controllable and improvable standard operations.
Knowledge code: 7.3.3
Version: v20260522
Author: Quality Think Tank