Predictive and Preventive Maintenance Flashcards
6 cards from real Millwright Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Predictive and Preventive Maintenance flashcards as text
What is the primary difference between preventive maintenance (PM) and predictive maintenance (PdM)?
Answer: PM is performed on a fixed schedule, while PdM is performed based on actual equipment condition data
Preventive maintenance follows a time-based or usage-based schedule regardless of equipment condition, while predictive maintenance uses condition monitoring data to determine when maintenance is actually needed.
In vibration analysis, what does a dominant 1x frequency (running speed) in the radial direction typically indicate?
Answer: Rotor imbalance
A dominant vibration peak at 1x running speed in the radial direction is the classic signature of rotor imbalance: the heavy spot causes one vibration cycle per revolution.
What does infrared thermography detect that is useful for predictive maintenance?
Answer: Abnormal heat patterns that indicate developing faults like loose connections, bearing wear, or insulation breakdown
Infrared thermography detects surface temperature patterns that reveal developing problems: hot spots from electrical resistance, overheating bearings, blocked heat exchangers, insulation failures, and steam trap malfunctions.
What information does oil analysis provide about equipment condition?
Answer: Wear metal content, contamination levels, and lubricant degradation that indicate component wear and fluid condition
Oil analysis identifies wear metals (indicating which components are wearing), contamination types and levels (dirt, water, coolant), and lubricant condition (viscosity, oxidation, additive depletion), providing comprehensive insight into both machine and fluid health.
What does MTBF (Mean Time Between Failures) measure?
Answer: The average operating time between failures for a repairable system, indicating reliability
MTBF is the average elapsed operating time between failures for a repairable system, calculated by dividing total operating time by the number of failures. Higher MTBF indicates greater reliability.
What is the purpose of ultrasonic detection in predictive maintenance?
Answer: To detect high-frequency sounds from air leaks, electrical arcing, and bearing defects that are inaudible to the human ear
Ultrasonic detectors translate high-frequency sound (20-100 kHz) into the audible range, enabling detection of compressed air leaks, electrical corona/arcing, and early-stage bearing faults that produce ultrasonic emissions.