Why Preventive Maintenance is Essential
Unplanned crusher downtime costs 5-10x more than scheduled maintenance. A well-planned preventive maintenance (PM) program identifies problems before they cause failure, optimizes component life and ensures consistent production. This guide provides a practical PM framework for crushing and screening operations.
Establishing a PM Culture
Successful preventive maintenance requires:
- Management commitment: Budget for parts, labor and planned downtime
- Trained personnel: Equipment-specific training for maintenance technicians
- Documentation: Clear procedures, checklists and record-keeping systems
- Parts inventory: Stock critical spares to minimize repair delays
- Condition monitoring: Use technology to detect problems early
Monthly Maintenance Routines
Crushing Equipment — Monthly
- Complete all daily and weekly tasks
- Perform complete visual inspection of all equipment
- Check drive belt tension and condition — replace if cracked or glazed
- Inspect all safety guards and emergency stops
- Check foundation bolts for tightness
- Verify all lubrication points are functioning
- Inspect and clean radiators and coolers
- Check electrical connections and motor condition
- Review maintenance logs for recurring issues
- Plan any repairs or parts replacements for next scheduled shutdown
Vibrating Screens — Monthly
- Inspect screen cloths for tears, wear and blinding
- Check tensioning mechanism operation
- Verify isolation mounts for deterioration or damage
- Lubricate all bearings (if grease-type)
- Check vibration amplitude and compare to baseline
- Inspect feedbox and discharge launders for wear
- Check belt conveyor condition (if separate)
- Clean material buildup from screen deck and frame
Conveyors — Monthly
- Inspect belt for cuts, tears, splice condition and tracking
- Check and adjust belt cleaner and scraper
- Lubricate all bearings (check oil levels or grease)
- Inspect idlers for rotation and wear
- Check pulley lagging condition
- Verify tensioning device operation
- Inspect structure for cracks, loose bolts or damage
- Test motion sensors and safety switches
Quarterly Maintenance Routines
Crushers — Quarterly Overhaul
Jaw Crushers:
- Measure jaw die wear and plan for replacement if at 70% worn
- Inspect and measure toggle plate and seat
- Check eccentric shaft for wear and alignment
- Inspect main bearings — check clearance and condition
- Replace hydraulic filter if equipped
- Check motor current draw vs. baseline (indicates wear changes)
- Inspect and adjust clearance between pitman and toggles
- Review and update wear part inventory
Cone Crushers:
- Perform oil analysis — send sample to laboratory
- Replace oil filter and lubricating oil
- Check head and bowl liner wear and plan replacement
- Inspect pinion gear and bevel gear for wear
- Check eccentric bushing clearance
- Verify hydraulic setting force and relief valve operation
- Inspect mantle and concave retention hardware
- Test alarm and safety systems
Impact Crushers:
- Measure blow bar remaining thickness — replace at 50%
- Inspect rotor for cracks and balance
- Check apron liner wear and adjustment
- Inspect anvil (grinding path) condition
- Check body liners for wear through
- Verify impact clearance settings
- Inspect and adjust feed chute for proper material presentation
Scheduled Maintenance Maximizes Plant Availability
Component Replacement Intervals
| Component | Typical Life (hours) | Replace When |
|---|---|---|
| Jaw dies (aggregate) | 1000-2500 | 70% worn or cracked |
| Cone liners | 1500-4000 | 50% thickness remaining |
| Impact blow bars | 500-2000 | 50% worn or cracked |
| Screen cloths | 500-1500 | Torn, 80% openings blocked |
| Conveyor belts | 2000-10000 | Severe damage or 30% cover wear |
| Idler bearings | 5000-15000 | Rough rotation or play |
| Crusher bearings | 5000-20000 | Noise, heat or clearance issues |
Record Keeping and Analysis
Every maintenance action should be documented. Key records include:
- Equipment logs: Operating hours, production, fuel/power consumption
- Maintenance history: Work performed, parts replaced, technicians involved
- Failure analysis: Root cause of any breakdown or component failure
- Parts consumption: Track actual wear part life vs. expected
- Oil analysis reports: Include in equipment files for trend analysis
Use this data to:
- Identify recurring problems requiring design changes
- Optimize PM intervals based on actual condition
- Improve parts ordering accuracy
- Demonstrate maintenance ROI to management
Planning for Shutdowns
Schedule major PM activities during planned production downtime:
- Prepare work order with detailed tasks and required parts
- Ensure all parts and tools are on-site before shutdown
- Assign qualified technicians and supervisors
- Complete all planned work — avoid partial shutdowns
- Commission and test equipment before restart
- Document actual work completed vs. planned
Measuring PM Program Effectiveness
Key Performance Indicators (KPIs):
- Overall Equipment Effectiveness (OEE): Target >85% for crushing operations
- Mean Time Between Failures (MTBF): Should increase over time with good PM
- Maintenance cost per ton: Should decrease as PM program matures
- Planned vs. unplanned maintenance ratio: Target 4:1 or higher
- Parts inventory turnover: Optimize to reduce carrying costs
A well-executed preventive maintenance program transforms a reactive operation into a proactive, high-performance crushing plant with predictable costs and maximum uptime.
