Equipment Management Series Issue 1: Autonomous Maintenance and Planned Maintenance — From "Fix When Broken" to "Equipment Self-Care"
Summary: Equipment breakdowns causing production line stops, maintenance teams running around like firefighters, and the same machine repeatedly malfunctioning—many companies' equipment management is still stuck in the "firefighting maintenance" phase. Autonomous Maintenance (AM) and Planned Maintenance (PM) are the foundations of Total Productive Maintenance (TPM) and lean systems. They involve operators in daily inspections and professional maintenance teams in preventive maintenance, aiming to nip issues in the bud. This article systematically explains the division of labor between AM and PM, the seven-step AM method, and key points for planning PM.
1. A Scenario: The Busier the Maintenance, the More Breakdowns
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. Maintenance comes, disassembles, and repairs it, and it runs again after a couple of hours—only to break down again next week." 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: In the past six months, unplanned downtime accounted for 68% of total downtime, with 40% of the breakdowns related to insufficient lubrication, tightening, and cleaning—not major issues, but the accumulation of minor oversights.
This is a typical Breakdown Maintenance model: equipment is ignored until it breaks down, and then it is rushed to repair. The cost is downtime, overtime, urgent spare part purchases, quality fluctuations, and maintenance personnel always dealing with recurring issues that weren't 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 Outcome |
|---|---|---|---|
| L0 | Breakdown Maintenance | No prevention | Unpredictable downtime |
| L1 | Planned Maintenance (PM) | Regular maintenance | Reduced breakdowns, still dependent on specialized teams |
| L2 | Autonomous Maintenance (AM) | Operator daily checks | Early detection, responsibility delegation |
| L3 | Predictive Maintenance (PdM) | Data/status monitoring | Replace parts 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 faults, 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 looseness.
- 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."
- Freeing Up Specialized Maintenance: Maintenance workers can shift from "greasing" to "analyzing root causes and improving design."
2. Relationship with Quality
Equipment condition directly affects process capability—wear on molds can lead to dimensional drift, loose fixtures can cause poor positioning, and insufficient cooling can result in deformation. AM is the embodiment of source quality control in the equipment dimension, aligning 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 | Preventing recontamination (covers, recycling, process improvements) |
| 3 | Establish Lubrication Standards | Visualizing lubrication points, grease types, cycles, and quantities |
| 4 | Tightening and Calibration | Torque for bolts, tension for belts, and baseline inspections |
| 5 | Inspection and Visual Management | Inspection checklists, color codes, and abnormal condition tags |
| 6 | Standardization | Standard AM procedures, training, and audits |
| 7 | Autonomous Management | Continuous improvement, team activities, and case sharing |
Key to Implementation: Each step must include standards (images + values) and audits; it should not be reduced to mere "cleaning."
4. Planned Maintenance (PM): What the Specialized Teams Do
Planned Maintenance is led by the equipment/engineering department and involves preventive work executed based on time or operating hours.
1. Common PM Types
| Type | Example |
|---|---|
| Regular Lubrication | Weekly/monthly/operating 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 Equipment List — Critical equipment classification (A/B/C), with the most comprehensive PM projects for Class A.
② Work Standards — SOPs for each PM task: steps, tools, spare parts, labor hours, and acceptance criteria.
③ Scheduling — Coordinated with production plans to avoid conflicts during peak delivery periods; utilize planned downtime windows.
④ Effectiveness 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, inspection, lubrication, tightening | In-depth maintenance, part replacement, precision adjustment |
| Records | Inspection checklists, abnormal reports | PM work orders, spare part consumption |
Interface: Abnormal conditions discovered by AM → Fill out Equipment Abnormal Report → PM/Maintenance receives the order → 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:
| Indicator | Meaning | Purpose |
|---|---|---|
| MTBF | Mean Time Between Failures | Measure reliability improvement |
| 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 checklists completed on time and to standard | Measure AM implementation |
| Recurrent Fault Rate | Proportion of the same type of fault recurring on the same equipment | Measure whether issues are fully resolved |
These indicators are directly related to downtime and adjustment downtime losses in OEE (7.3.1, see Lean Manufacturing Series Issue 3)—improving AM/PM naturally increases the time operation rate of OEE.
6. Common Misconceptions
Misconception One: Autonomous Maintenance = Reducing Maintenance Staff. Incorrect. AM is about optimizing roles, not downsizing; specialized teams should focus on improvements and complex faults.
Misconception Two: PM is Only on the Calendar, Not Linked to Production. Incorrect. PM must be coordinated with production plans; otherwise, it will either be skipped or cause complaints.
Misconception Three: Inspection Checklists Filled with "Normal" as a Formality. Incorrect. Inspections without abnormalities still require random audits; filling all as normal often indicates ineffective inspections.
Misconception Four: Only Maintenance, No Root Cause Analysis. Recurring faults should trigger root cause analysis (5 Whys, fishbone diagram), and design or spare part specifications should be modified if necessary.
7. Conclusion
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 "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 Number: 7.3.3
Version: v20260522
Author: Quality Excellence Think Tank