7.3 Maintenance Strategies

7.3 Maintenance Strategies

1. Breakdown Maintenance (Reactive Maintenance)

1.1 Definition and Concept

1. Fundamental Approach: "Run-to-Failure" strategy.

2. Core Principle: Equipment is operated until it fails, with repairs conducted only after breakdown occurs.

3. Philosophy: No proactive intervention; maintenance is purely reactive.

1.2 Characteristics

1. Unplanned Nature:

   • Emergency repairs with no prior scheduling.

   • Work orders created after failure detection.

2. Resource Requirements:

   • Standby repair crews on-call.

   • Emergency spare parts inventory.

   • Rapid response capability.

3. Cost Structure:

   • High emergency labor rates.

   • Premium costs for expedited parts.

   • Production losses during downtime.

1.3 Implementation Process

1. Failure Occurrence: Equipment stops functioning.

2. Diagnosis: Troubleshooting to identify root cause.

3. Repair Planning: Determining required parts and labor.

4. Execution: Conducting repairs.

5. Testing: Verifying equipment functionality.

6. Return to Service: Recommissioning equipment.

1.4 Advantages

1. Lower Initial Costs:

   • No investment in preventive measures.

   • Minimal planning resources required.

2. Simple Implementation:

   • No complex scheduling systems.

   • Easy to understand and execute.

3. Suitable for Certain Situations:

   • Non-critical equipment with low failure impact.

   • Equipment with unpredictable failure patterns.

   • Redundant systems with backup capabilities.

1.5 Disadvantages

1. High Downtime Costs:

   • Unplanned production interruptions.

   • Extended repair times due to diagnosis.

2. Increased Repair Costs:

   • Secondary damage from catastrophic failures.

   • Emergency parts procurement premiums.

3. Safety Risks:

   • Unexpected failures can cause accidents.

   • No warning before critical failures.

4. Poor Resource Utilization:

   • Inefficient use of maintenance personnel.

   • Higher overall maintenance costs.

1.6 Applications

1. Non-Critical Equipment: Failure doesn't affect core operations.

2. Redundant Systems: Backup available during repairs.

3. Low-Value Assets: Replacement cost lower than preventive maintenance.

4. Predictably Unpredictable Failures: Random failures with no warning signs.

2. Preventive Maintenance (PM)

2.1 Definition and Concept

1. Proactive Approach: Scheduled interventions before failure.

2. Core Principle: "Prevention is better than cure."

3. Objective: Reduce probability of failure through planned activities.

2.2 Types of Preventive Maintenance

1. Time-Based Maintenance:

   • Scheduled at fixed time intervals (daily, weekly, monthly).

   • Based on calendar time.

2. Usage-Based Maintenance:

   • Triggered by operational hours, cycles, or production units.

   • Based on equipment runtime.

3. Opportunity-Based Maintenance:

   • Performed during planned shutdowns or low-activity periods.

   • Coordinated with production schedules.

2.3 Key Activities

1. Regular Inspections:

   • Visual checks and measurements.

   • Non-destructive testing.

2. Scheduled Servicing:

   • Lubrication and cleaning.

   • Calibration and adjustments.

3. Component Replacement:

   • Based on expected life cycles.

   • Before wear-out phase begins.

4. Condition Monitoring:

   • Basic parameter checking.

   • Performance trend analysis.

2.4 Implementation Process

1. Equipment Criticality Analysis:

   • Identifying maintenance priorities.

   • Risk assessment of failure consequences.

2. Maintenance Planning:

   • Developing maintenance schedules.

   • Creating standard operating procedures.

3. Resource Allocation:

   • Spare parts planning.

   • Labor scheduling.

4. Execution and Documentation:

   • Performing scheduled tasks.

   • Recording maintenance history.

5. Review and Optimization:

   • Analyzing maintenance effectiveness.

   • Adjusting intervals based on experience.

2.5 Advantages

1. Increased Reliability:

   • Reduced frequency of unexpected failures.

   • Higher equipment availability.

2. Extended Equipment Life:

   • Slower deterioration rates.

   • Optimal operating conditions maintained.

3. Better Planning:

   • Scheduled downtime.

   • Predictable maintenance costs.

4. Improved Safety:

   • Identification of potential hazards.

   • Controlled working environment.

5. Cost Efficiency:

   • Planned parts procurement.

   • Efficient labor utilization.

2.6 Disadvantages

1. Potential Over-Maintenance:

   • Replacing components with remaining useful life.

   • Unnecessary downtime for servicing.

2. High Initial Setup:

   • Requires detailed planning and systems.

   • Training investment for personnel.

3. Not Failure-Proof:

   • Cannot prevent all failures.

   • May miss early warning signs.

4. Resource Intensive:

   • Regular commitment of manpower.

   • Continuous monitoring required.

2.7 Applications

1. Critical Production Equipment: Where downtime costs are high.

2. Safety-Critical Systems: Equipment affecting personnel safety.

3. Predictable Wear Patterns: Components with known life cycles.

4. High-Value Assets: Equipment where replacement costs are significant.

3. Total Productive Maintenance (TPM)

3.1 Definition and Philosophy

1. Holistic Approach: Company-wide equipment maintenance.

2. Core Objective: Maximize Overall Equipment Effectiveness (OEE).

3. Fundamental Principle: "Everyone maintains their own equipment."

3.2 The Eight Pillars of TPM

1. Autonomous Maintenance:

   • Operators perform basic maintenance.

   • Daily cleaning, inspection, lubrication.

   • Early problem detection by users.

2. Planned Maintenance:

   • Specialists handle complex maintenance.

   • Scheduled overhauls and repairs.

   • Maintenance planning and scheduling.

3. Focused Improvement:

   • Small group activities for continuous improvement.

   • Problem-solving teams.

   • Kaizen events for optimization.

4. Quality Maintenance:

   • Zero defect mindset.

   • Error-proofing (Poka-Yoke).

   • Root cause analysis of quality issues.

5. Early Equipment Management:

   • Maintenance considerations in design phase.

   • Easy-to-maintain equipment design.

   • Lifecycle cost optimization.

6. Education and Training:

   • Skill development for all employees.

   • Multi-skilled workforce.

   • Knowledge sharing systems.

7. Safety, Health, and Environment:

   • Zero accident culture.

   • Ergonomic improvements.

   • Environmental impact reduction.

8. Office TPM:

   • Extending TPM principles to administrative functions.

   • Support department efficiency.

   • Cross-functional collaboration.

3.3 Implementation Methodology

1. Management Commitment:

   • Top-level support and leadership.

   • Resource allocation for TPM implementation.

2. Initial Education:

   • TPM awareness programs.

   • Training on basic concepts.

3. Pillar Implementation:

   • Sequential or parallel pillar activation.

   • Pilot projects for demonstration.

4. Performance Measurement:

   • OEE tracking and analysis.

   • Key Performance Indicators (KPIs).

5. Continuous Improvement:

   • Regular review and adjustment.

   • Cultural integration.

3.4 Overall Equipment Effectiveness (OEE)

1. Calculation Formula: $\text{OEE} = \text{Availability} \times \text{Performance} \times \text{Quality}$

2. Components:

   • Availability: Uptime percentage. $\text{Availability} = \frac{\text{Operating Time}}{\text{Planned Production Time}}$

   • Performance: Speed efficiency. $\text{Performance} = \frac{\text{Ideal Cycle Time} \times \text{Total Count}}{\text{Operating Time}}$

   • Quality: Good product percentage. $\text{Quality} = \frac{\text{Good Count}}{\text{Total Count}}$

3. World-Class OEE: Typically >85%.

3.5 Benefits

1. Operational Improvements:

   • Increased equipment availability.

   • Higher production output.

   • Reduced defects and rework.

2. Cultural Changes:

   • Ownership mentality among operators.

   • Cross-functional collaboration.

   • Problem-solving culture.

3. Financial Benefits:

   • Lower maintenance costs.

   • Higher asset utilization.

   • Improved return on investment.

4. Quality Enhancements:

   • Consistent product quality.

   • Reduced variability.

   • Customer satisfaction improvement.

3.6 Challenges

1. Cultural Resistance:

   • Traditional operator vs maintenance roles.

   • Initial skepticism about new approach.

2. Implementation Time:

   • Long-term commitment required.

   • Gradual results realization.

3. Training Requirements:

   • Extensive skill development.

   • Continuous learning culture.

4. Measurement Complexity:

   • Accurate data collection systems.

   • Consistent performance tracking.

4. Condition Monitoring (Predictive Maintenance)

4.1 Definition and Concept

1. Data-Driven Approach: Maintenance based on actual equipment condition.

2. Core Principle: "Monitor and predict, then act."

3. Objective: Detect early signs of failure and schedule maintenance accordingly.

4.2 Condition Monitoring Techniques

1. Vibration Analysis:

   • Monitoring frequency and amplitude of vibrations.

   • Detects imbalance, misalignment, bearing wear.

   • Uses accelerometers and spectrum analyzers.

2. Thermography:

   • Infrared imaging to detect temperature variations.

   • Identifies electrical hotspots, insulation failures.

   • Non-contact temperature measurement.

3. Oil Analysis:

   • Testing lubricant properties and contamination.

   • Detects wear particles, chemical changes.

   • Predictive of bearing and gear wear.

4. Ultrasonic Testing:

   • Detection of high-frequency sounds.

   • Identifies leaks, electrical discharges.

   • Early detection of bearing failures.

5. Motor Current Analysis:

   • Monitoring electrical characteristics.

   • Detects rotor bar defects, winding issues.

   • Identifies mechanical load variations.

6. Performance Monitoring:

   • Tracking operational parameters.

   • Efficiency trends and deviations.

   • Energy consumption analysis.

4.3 Implementation Framework

1. Equipment Selection:

   • Criticality analysis.

   • Cost-benefit assessment.

2. Technology Selection:

   • Appropriate monitoring techniques.

   • Sensor and instrumentation selection.

3. Baseline Establishment:

   • Normal operating condition profiles.

   • Threshold limit setting.

4. Data Collection:

   • Continuous or periodic monitoring.

   • Automated data acquisition systems.

5. Analysis and Interpretation:

   • Trend analysis and pattern recognition.

   • Expert system or AI-based analysis.

6. Decision Making:

   • Maintenance scheduling based on findings.

   • Priority setting for interventions.

4.4 Data Management

1. Collection Systems:

   • Portable data collectors.

   • Permanent online monitoring.

   • Wireless sensor networks.

2. Analysis Software:

   • Trend analysis tools.

   • Predictive algorithms.

   • Failure mode databases.

3. Integration Platforms:

   • Computerized Maintenance Management Systems (CMMS).

   • Enterprise Asset Management (EAM) systems.

   • Industrial Internet of Things (IIoT) platforms.

4.5 Advantages

1. Optimized Maintenance:

   • Maintenance only when needed.

   • Maximum utilization of component life.

2. Reduced Downtime:

   • Planned interventions during convenient periods.

   • Shorter repair times with prepared resources.

3. Failure Prevention:

   • Early detection of developing faults.

   • Prevention of catastrophic failures.

4. Cost Efficiency:

   • Reduced spare parts inventory.

   • Lower labor costs through efficient scheduling.

5. Improved Safety:

   • Early warning of hazardous conditions.

   • Controlled maintenance environment.

4.6 Limitations

1. High Initial Investment:

   • Monitoring equipment and systems.

   • Training and expertise development.

2. Technology Dependence:

   • Requires specialized knowledge.

   • System reliability and calibration needs.

3. Not Universal:

   • Not suitable for all failure modes.

   • Some failures occur without warning.

4. Data Management Challenges:

   • Large volumes of data to analyze.

   • Interpretation expertise required.

4.7 Applications

1. Rotating Machinery: Pumps, motors, turbines, fans.

2. Electrical Systems: Transformers, switchgear, cables.

3. Process Equipment: Heat exchangers, compressors, conveyors.

4. Critical Infrastructure: Power generation, transmission systems.

5. Strategy Selection and Integration

5.1 Selection Criteria

1. Equipment Criticality:

   • Impact on production.

   • Safety implications.

   • Replacement cost.

2. Failure Characteristics:

   • Predictability of failures.

   • Failure progression rate.

   • Detection difficulty.

3. Cost Considerations:

   • Monitoring vs maintenance costs.

   • Downtime costs.

   • Implementation investment.

4. Organizational Capability:

   • Technical expertise available.

   • Existing maintenance culture.

   • Resource availability.

5.2 Hybrid Approaches

1. Combination Strategies:

   • Preventive maintenance for time-based wear.

   • Condition monitoring for unpredictable failures.

   • Breakdown maintenance for non-critical items.

2. Risk-Based Maintenance:

   • Maintenance frequency based on risk assessment.

   • Criticality-based resource allocation.

   • Dynamic adjustment of maintenance plans.

5.3 Implementation Roadmap

1. Current State Assessment:

   • Existing maintenance practices evaluation.

   • Equipment criticality analysis.

2. Strategy Development:

   • Appropriate strategy selection for each asset.

   • Technology and tool selection.

3. Pilot Implementation:

   • Selected equipment or area.

   • Proof of concept demonstration.

4. Full-Scale Rollout:

   • Phased implementation.

   • Training and change management.

5. Continuous Improvement:

   • Performance monitoring.

   • Strategy refinement and optimization.

5.4 Key Performance Indicators

1. Maintenance Effectiveness:

   • Overall Equipment Effectiveness (OEE).

   • Mean Time Between Failures (MTBF).

   • Mean Time To Repair (MTTR).

2. Cost Metrics:

   • Maintenance cost per unit output.

   • Inventory turnover ratio.

   • Emergency maintenance percentage.

3. Reliability Metrics:

   • Equipment availability.

   • Schedule compliance.

   • Preventive maintenance completion rate.

6. Conclusion: Strategic Integration

Effective maintenance management requires:

1. Balanced Approach: Combining strategies based on equipment needs.

2. Data-Driven Decisions: Utilizing condition monitoring for optimization.

3. Cultural Foundation: TPM principles for organizational engagement.

4. Continuous Evolution: Adapting strategies based on performance and technology.

5. Strategic Alignment: Maintenance objectives supporting business goals.

The optimal maintenance strategy evolves from reactive to proactive, integrating preventive, predictive, and reliability-centered approaches to maximize asset performance while minimizing total lifecycle costs.