▶What is the difference between preventive, predictive, and reactive maintenance?
Preventive maintenance (PM) is scheduled, routine service (oil change every 1,000 hours, filter every 500 hours). It prevents many failures but may do unnecessary work if something is still good. Predictive maintenance (PdM) uses monitoring (temperature, vibration, sound) to predict failures before they occur. A temperature rise or vibration spike signals a bearing failure is coming; you fix it before it fails, avoiding unexpected downtime. PdM saves money (don't service things that don't need it) but requires investment in monitoring equipment and data analysis. Reactive maintenance (run until failure, then fix) is cheapest upfront but most expensive overall (downtime, equipment damage, emergency labor). Best practice: combine PM (basic schedule) with PdM (monitor for early signs of trouble).
▶How do I create a preventive maintenance schedule for a piece of equipment?
Start with the equipment manual: it specifies service intervals (oil change, filter, inspection, overhaul). Document all required services and their intervals (hours of operation, calendar time, or both). Create a schedule (spreadsheet or software) listing each service, its interval, and who is responsible. Track completion (date performed, technician, results). Example: a compressor might require oil change every 500 hours, air filter every 250 hours, complete inspection every 2,000 hours, and overhaul every 10,000 hours. Follow the schedule consistently; skipped PM leads to failures and repair costs that exceed the cost of the PM. Prioritize: critical equipment (production, life-safety) gets tighter schedules; less critical equipment can have longer intervals.
▶What should I inspect during routine maintenance?
Inspections are visual and physical checks for problems: (1) Leaks (oil, coolant, hydraulic fluid) indicate seal failure. (2) Corrosion or rust indicate moisture or chemical exposure. (3) Cracks in castings or welds indicate imminent failure. (4) Loose bolts or fasteners affect operation. (5) Unusual sounds (grinding, squealing, knocking) indicate bearing or alignment problems. (6) Vibration (feel the equipment while running; some vibration is normal, but excessive is a sign of trouble). (7) Temperature (use a non-contact thermometer; hot spots indicate friction or electrical overload). (8) Electrical parameters (voltage, current, ground continuity). Document findings (condition OK, needs adjustment, needs repair soon, needs replacement). Photos or video are helpful for trending over time.
▶How do I document preventive maintenance and why is it important?
Documentation includes: date, equipment name, services performed, parts replaced, hours or meters read, inspection findings, technician name. Create a logbook (physical or digital) recording this information for each piece of equipment. Over time, trends become visible: oil consumption increasing (seal wearing), temperature rising (cooling fan failing), vibration growing (bearing degrading). These trends predict failure and allow proactive scheduling of repair. Documentation also protects the company legally (proves due diligence in maintenance) and helps the next technician understand the equipment's history. Warranty often requires documented PM; skipping documentation voids the warranty.
▶What is condition monitoring and how is it used?
Condition monitoring is continuous or frequent measurement of equipment parameters (temperature, vibration, oil analysis, pressure, electrical performance) to detect changes that indicate problems. Tools: thermography (infrared camera) spots hot spots; vibration meters detect bearing wear; oil analysis (particle count, viscosity, water content) detects internal wear; current signature analysis identifies electrical problems. Trends (data over weeks or months) are more informative than single measurements. Example: bearing temperature baseline is 160°F. A trend showing 160°F, 162°F, 165°F, 170°F, 176°F predicts failure in a week; a single 176°F reading without trend context is ambiguous. Modern systems log data automatically and alert when thresholds are exceeded.
▶What is the cost-benefit of preventive maintenance?
PM costs money upfront (labor, parts, scheduled downtime) but saves money long-term. A typical cost analysis: a $50k machine failing unexpectedly costs $20k to repair plus $100k in production downtime (8-hour repair, 40 product units lost at $2,500 each) = $120k loss. A PM program costing $5k/year (spare parts, labor, downtime for maintenance) prevents most failures. Over 10 years: PM cost = $50k; average reactive maintenance cost = $50-100k per failure. If PM prevents two major failures in 10 years, it pays for itself many times over. The math varies by industry, equipment, and risk tolerance, but the principle is clear: preventing failures is cheaper than fixing them.
▶How do I prioritize when there are many pieces of equipment and limited resources?
Rank equipment by criticality: life-safety (fire systems, emergency equipment) gets top priority. Production equipment (directly affects revenue) is next. Support equipment (less critical) is lower priority. Within each tier, prioritize by failure consequence and failure likelihood. Equipment with high failure likelihood and high consequence gets first attention. Use a risk matrix (criticality × probability) to score each piece of equipment. Allocate resources to the highest-risk items first. As capacity allows, work down the list. A maintenance management system (software) helps track this; it flags due maintenance and prioritizes by consequence. Without prioritization, maintenance becomes reactive (fixing failures) rather than preventive.
