What is Preventive Maintenance?
Preventive maintenance (or preventative maintenance) consists of regular and systematic inspection, cleaning, lubrication, component replacement and overhaul of equipment to prevent breakdowns before they actually occur.
Instead of waiting for failures, assets are proactively maintained as per predetermined schedules. The goal of preventive maintenance is to extend the useful operational lifetime of systems by curbing degradation through consistent care and upkeep.
Proper preventive maintenance significantly improves plant and equipment reliability. Let‘s examine why this matters.
The High Costs of Downtime
Unplanned downtime cripples production and requires scramble repairs costing 5-20 times more than planned work. According to studies, over 50% of asset downtime arises from unexpected breakdowns with the rest occurring during maintenance windows.
With an average facility losing 5-20% annually in productivity, reducing downtime provides a quick ROI. Other cascading costs include business disruption, contractual penalties, reputational damage and safety risks.
Maximizing Uptime With Preventive Maintenance
Preventive maintenance enhances asset availability by catching degradation early. Issues like loose wiring, worn gears, eroded pipes, cracked belts, corroded tanks, fouled fluids, overloaded circuits and embrittled rubber are all easily corrected before causing functional failure.
Without preventive maintenance, such incipient defects sustain further wear until assets suffer:
- Intermittent operation
- Declining quality/output
- Increased energy consumption
- Reduced operating margins
- Total breakdowns
Planned maintenance prevents this through:
- Systematic inspections
- Testing and diagnostics
- Component replacement
- Cleaning and lubrication
- Overhauls
- Defect elimination
Reliability increases while lifetime equipment costs are lowered over the long term.
Maintenance Cost Optimization
As seen in the bathtub curve, equipment faces high breakdown rates when new and just before wearing out. Preventive maintenance aims to extend the reliable mid-life period where failure rates are minimized.
The initial years see manufacturing defects that escaped quality control. By replacing defective components early rather than troubleshooting repetitively, maintenance costs are reduced.
In later years, components deteriorate beyond economic repair. But rebuilding/replacing items before end of technical life is cheaper than replacing entire units during breakdown.
Typical Maintenance Cost Distribution
Studies across industries reveal almost 70% of maintenance cost is spent fixing emergency breakdowns.
Preventive maintenance helps redistribute this ratio with higher investment in prevention and lower forced repairs. Cost optimization occurs when spending is balanced.
Next let‘s examine popular PM methodologies.
Types of Preventive Maintenance
There are four main types of preventive maintenance programs:
Time-based Preventive Maintenance
This involves maintenance tasks triggered according to predetermined intervals of time. For example:
- Clean HVAC filters monthly
- Inspect forklifts quarterly
- Tuneup generator sets annually
Simple to establish, time-based PM works well if asset deterioration is governed mainly by age regardless of actual usage. It also helps compliance with regulations and warranty requirements.
However, the fixed intervals are rough estimates often leading to premature or missed maintenance.
Usage-based Preventive Maintenance
Here maintenance operations are scheduled based on measurable usage rather than just time. This accounts for actual wear and tear seen in:
- Engine oil changes after 500 run hours
- Inspecting aircraft turbines after 2000 flight cycles
- Pump rebuilds after 15,000 start/stop cycles
By factoring intensity of use, PM can be more precise than fixed time intervals alone. However, manual data collection may be cumbersome.
Condition-based Preventive Maintenance
This employs predictive maintenance tools to assess asset health 24/7 based on data like vibration, temperature and pressure rather than arbitrary schedules.
Analytics models then optimize PM tasks based on actual degradation instead of estimates. This maximizes useful life while avoiding premature maintenance.
Design-focused Preventive Maintenance
Also called proactive maintenance, this involves enhancing inherent reliability during system design and installation using techniques like:
- Derating components to reduce failure rates
- Adding redundancies to minimize downtime
- Designing for maintainability with quick access
- Structured wiring and piping discipline
- Oversize drains and dirt legs
- Smooth finishes to avoid material accumulation
Building robustness upfront leads to simpler maintenance programs over the lifecycle.
Now let‘s discuss key technologies facilitating modern preventive maintenance.
Enabling Tools and Technologies
Preventive maintenance is enhanced by various technologies:
Inspection Drones – Drones equipped with cameras and sensors simplify visual asset inspections while reducing risks. Thermal drones detect hotspots and moisture ingress.
Vibration Analyzers – By tracking vibration signatures, analyzers find imbalances, looseness, bearing faults and other defects before failure.
Oil Analysis – Checks for particulate levels, viscosity variation and contamination spot lubrication issues in rotating equipment. Helps safely extend drain intervals.
Process Parameters – Monitoring factors like pressure, flow, voltage, speed, load and temperature finds performance issues. Statistical models identify deviations.
Ultrasound Testing – Detects air leaks, steam traps failures, valve issues and electrical faults via sound waves without equipment teardown.
Automation – IoT sensors coupled with software platforms enable real-time equipment monitoring, data historians, maintenance scheduling and work order systems.
These technologies provide comprehensive visibility into asset health for highly optimized preventive maintenance. Let‘s go through the workflow step-by-step now.
Steps in the Preventive Maintenance Process
Effective preventive maintenance involves systematically executing a few key steps:
1. Asset Register and Criticality
Keep updated records of all equipment, machines, systems and components involved in delivering the final product along with nameplate data.
Determine asset criticality based on factors like maintenance costs, downtime impact, spare part availability and redundancy.
2. Maintainability Analysis
Study failure modes and access requirements. List parts prone to periodic replacement. Make modifications if needed to improve safety, reliability and maintainability.
3. Maintenance Task Creation
Decide appropriate tasks like inspections, measurements, overhauls, lubrication and part replacement needed to maintain assets. Reference manuals, past work orders and OEM guidelines.
4. Maintenance Scheduling
Determine suitable maintenance intervals based on time factors, usage metrics or condition parameters. Calendar schedules for simpler time-based tasks while software tools schedule predictive maintenances.
5. Work Execution
Follow standard procedures for each job detailing parts, hazards, troubleshooting steps, reassembly instructions and documentation. Use checklists and permit-to-work systems where required.
6. CMMS and Data Capture
Record work order details like date, asset, description, steps taken, measurements, findings, replacements done, time spent, etc. Ensure integration with analysis tools.
7. Continual Improvement
Use DMARCA root cause analysis to drive procedure changes. Modify type and frequency of tasks based on tech feedback. Introduce better technologies. Sustain gains through leadership involvement.
Now let‘s look at some real world examples demonstrating the impact of structured preventive maintenance programs.
Real World Examples of Preventive Maintenance
Here are some application cases highlighting benefits reaped across sectors:
Smelter Crane – Electrical Preventive Maintenance
A large smelter relies on an overhead crane with 1500 kW traction motors for material handling.
Bearing fluting noticed during inspections led to predictive testing revealing phase-to-phase arcing, impeded ventilation and overloaded transmission cables.
Before production halts occurred, a scheduled overhaul saw cables upgraded, motors rewound, brakes/bearings replaced and contactors changed – all identified via preventive maintenance.
Benefits
- Projected savings of $3.7M from 50 hours of avoided downtime per year plus 6-8 years extra service life.
- Improved worker safety from reduced voltage fluctuations.
Aircraft Fleet – Fuel Efficiency
An airline with 160 aircraft found its fuel spend 9% over budget last year mostly from two models. Engineers discovered worn seals, surface contamination and paint erosion on wings and fuselages upon inspection.
Wind tunnel and computational fluid dynamics tests confirmed the degraded surface finish raised drag and fuel needs. A structured preventive cleaning, polish and sealant reconditioning program was implemented fleetwide during overnight layovers.
Benefits
- Fuel efficiency improved by 3% saving $7.8M annually
- Greenhouse gas emissions cut by 30,000 tonnes per year
Ocean Liner – Corrosion Prevention
A cruise company noticed accelerated corrosion in ballast tanks shortening ship lifespan. Upon review, protective coatings were found failing prematurely.
Investigation revealed issues with surface prep, atmospheric controls, application techniques, quality inspection and coating selection. Engineers revamped corrosion standards focusing on prevention during design, newbuild and maintenance.
Benefits
- $30M savings from doubling intervals between drydocking
- Improved passenger experience through reduced vibrations
There are many more such success stories. Now let‘s discuss things to keep in mind when establishing your maintenance strategy.
Crafting an Effective Preventive Maintenance Program
For an efficient preventive maintenance system, keep these tips in mind:
Secure Leadership Buy-in
Educate management on PM benefits. Have realistic budgets supporting necessary headcount, software, outsourcing and parts inventory.
Incorporate Safety Lessons
Let past incidents guide your maintenance priorities instead of just production metrics. Address risks revealed by analyses like HAZOP and FMECA.
Design for Maintainability
Ensure equipment accessibility for inspection and repairs without teardown. Standardize components across assets.
Utilize Digital Tools
Deploy monitoring sensors, mobile access CMMS software for efficient data capture. Add analytics for deeper insights.
Adopt Condition Monitoring
Transition towards predictive maintenance to catch faults ultra early. Schedule tasks based on parameters like cracks, negative pressure, increased current draw.
Refine Over Time
Continually adjust tasks and intervals based on findings, DMARCA and tech feedback. Pursue excellence through kaizens.
Proper implementation leads to a self-reinforcing cycle of increasing productivity and asset lifespan while driving down lifetime costs.
Next let’s go over common missteps to avoid.
Preventive Maintenance Pitfalls
While extremely beneficial, poor execution can diminish potential gains. Steer clear of these mistakes:
- Inadequate planning leading to firefighting culture
- Low quality spare parts causing early failures
- Task intervals set arbitrarily rather than data-based
- Ignoring collateral damage from failures
- Inconsistent work methods between shifts
- Work backlogs exceeding 30 days
- Failure to document repairs affecting analytics
- No root cause failure analysis
- Lack of monitoring for condition-based PM
Now let’s see how preventive maintenance complements predictive maintenance.
Preventive, Predictive and Reliability Centered Maintenance
Modern programs blend multiple techniques:
Preventive – Time or use-based maintenance servicing assets before failure regardless of condition. Aims to extend standard lifecycle.
Predictive – Condition monitoring and non-destructive testing to assess health and fix minor defects before operational impact. Seeks to maximize useful life.
Reliability Centered – Redesigns systems to reduce failure rates rather than repairing defects. Focuses on inherent availability.
Reliability centered maintenance increases baseline dependability while preventive and predictive work preserves this. Best practice utilizes all three in a layered strategy.
Now let‘s examine the technology roadmap shaping future maintenance.
The Intelligent Maintenance Revolution
Emerging innovations like IoT sensors, augmented reality, drones, robotics, artificial intelligence and machine learning are transforming maintenance.
Smarter Devices – Chips embedded in equipment coupled with LPWAN connectivity enable continuous remote telemetry at low costs. Vibration, temperature, RPM and other proxies for health get tracked constantly.
Digital Twins – High fidelity equipment models in software driven by operating data learn precise failure signatures. They predict when parts need replacement via simulation.
Augmented Workers – Wearables like smart glasses overlay asset telemetry, manual excerpts, expert audio/video guidance and document action in the field mechanic‘s view in real-time.
Robotic Automation – Bots handle hazardous confined space inspection, fastidious tasks like surface treatment and repetitive jobs leaving humans for cognitive functions.
AI Failure Models – Complex multidimensional machine learning algorithms on cloud systems discern equipment failure risk likelihood given all operating parameters.
Tools like these enable predictive maintenance at scale using precise data unavailable manually. This reduces uncertainty in planning and exponentially boosts technician productivity.
Now that we‘ve covered core concepts, let‘s summarise key takeaways.
In Closing – Main Takeaways
We’ve seen why attentive preventive maintenance matters for profitability, compliance and sustainability. With costs often 30 times higher for reactive repairs, holistic prevention provides quick ROI.
This guide explained various maintenance approaches, steps for structured programs, field examples and technologies that pave the smart future driven by data.
Here are main insights to retain:
- Preventive maintenance enhances uptime, extends asset lifespan and optimizes TCO
- Condition monitoring via analytics sharpens forecasting over arbitrary schedules
- Technology like IoT sensors and AR make technicians vastly more productive
- Change management ensures continuity as techs and supervisors transition
- Document failures and positive contributions to continually improve
- Keep staff skills current regarding tools, diagnostics and safe methods
What aspects of preventive maintenance have you found to drive the most value? Share your experiences below!
