Preventive and Predictive Maintenance
The spectrum
Reactive (run to failure - fine for noncritical, cheap items), preventive (time- or usage-based tasks such as lubrication routes, filter changes, belt inspections), predictive/condition-based (measured condition drives the work order), and proactive (root-cause elimination). A CMMS tracks assets, work orders, PM schedules, parts, and history; without history, PM intervals are guesses.
Condition monitoring tools
Vibration analysis: overall velocity for general severity, acceleration for high-frequency bearing defects, displacement for low-speed machines. In a spectrum, 1× running speed points to unbalance, 2× to misalignment or looseness, and high-frequency broadband with bearing defect frequencies points to bearing damage. Thermography finds loose connections, overloaded circuits, and failing bearings - scanned under load. Oil analysis reports wear metals, water, viscosity, and particle counts. Ultrasound locates compressed-air leaks, steam trap failures, and early bearing friction.
Failure patterns
Most failures are not sudden; they give warning. Establishing a baseline when equipment is healthy is what makes later readings meaningful.
Traps
Take a vibration reading in the wrong units or without a baseline; perform IR scans on unloaded equipment; extend PM intervals without data; use PMs to mask a repeated root cause instead of doing the 5-Why or fishbone analysis.
Worked example
A pump shows a rising 2× peak with high axial vibration that grew after a motor replacement. That signature is misalignment, so the work order is a laser alignment, not a bearing replacement. The 1× peak, by contrast, would have pointed to balance.