6.3 Predictive Maintenance (PdM)

Predictive Maintenance (PdM)is transitionsnot facilityabout managementfixing frommachines; fixed-scheduleit replacementis toabout condition-basedbuying intervention.time. While Preventive Maintenance relies on statistical averagesguesses (replacing aparts bearing"just everyin 5,000 hours)case"), PdM utilizesinterrogates real-timethe dataasset for physical signatures of distress—heat, vibration, and noise. This shifts the operational reality from "Run-to-Failure" to "Run-to-Managed-Intervention." We do not wait for the bearing to seize at 2:00 AM; we detect the precursor10-micron signaturesdefect ofthree failureweeks (vibration, heat, ultrasonic noise). This methodology eliminates unnecessary part replacementsprior and prevents catastrophic machine failures that occur beforeschedule the scheduledchangeover maintenanceduring window.lunch.

Vibration Analysis (The Heartbeat)

Rotating assets,assets specifically(Reflow reflowblowers, ovenWave convectionimpellers) blowersspeak andbefore wavethey solderfail. impellers,By mustthe betime monitoredyou forhear mechanicala imbalance,noise, misalignment,the ordamage bearingis fatigue.already catastrophic.

• MetricMetric:: Velocity (mm/s RMS).
• If Vibration is the standard metric for machines operating between 600 and 12,000 RPM.
• Measurement Points: Sensors must be placed on the bearing housing in the horizontal, vertical, and axial planes.
• Thresholds (ISO 10816-3 Class I):
  • < 2.8 mm/s: Good-> /Then Acceptable.Asset is Healthy.
  • If Vibration is 2.8 – 4.5 mm/s: -> Then Flag as Warning.
    • Action: Increase monitoring frequency to daily.Daily. Order spare parts immediately.
  • If Vibration is > 4.5 mm/s: -> Then Asset is Critical.
    • Action: MachineSchedule mustdowntime bewithin scheduled24 forhours. immediateFailure bearingis replacement.
    imminent.
  • MandateDiagnostic:: All1x Reflow Oven convection motors must be measured monthly. A rise in vibrationRPM amplitude atspike 1x= RPM indicates imbalanceImbalance (fanDirty build-up);Fan). a rise at non-Non-synchronous frequenciesspike indicates= bearingBearing defects.Defect.

Infrared Thermography (IR)The Fever)

ThermalResistance imagingcreates heat. In electrical systems, heat is mandatorythe forprecursor detectingto high-resistancefire. connections in electrical panels andIn mechanical frictionsystems, inheat driveis systems.the signature of friction.

• Electrical Panels & Busbars:

  loose connections generate heat due to increased resistance ($P = I^2R$).
  • Delta-If Delta T Limit: Any connection showing a temperature rise ofis >5 C over a reference phase or ambient baseline requires retorquing. A rise of >20 C requires immediate shutdown and component replacement.
• Mechanical Systems:
  • Motors: Housing temperatures exceeding 80 5˚C (orvs. manufacturerReference rating)Phase) indicate-> Then Re-torque connection.
  • If Delta T is > 20˚C -> Then Immediate Shutdown. The component is failing.

  Mechanical Drive Systems

  • If Motor Housing > 80˚C -> Then Inspect winding insulation breakdownand or ventilation failure.ventilation.
  • Gearboxes:Physics: LocalizedFor hotevery spots10˚C indicaterise lubricationabove failurerated ortemperature, misalignment.
  insulation life is cut by 50%.

Ultrasonic Leak Detection (The Hiss)

Compressed air and Nitrogen (N2) leaks are oftenexpensive inaudibleand toinvisible. theA human"quiet" earfacility butcan generatestill high-frequencybe turbulencebleeding identifiablethousands byof ultrasonicdollars detectors.in gas costs.

• Compressed Air Lines:

  Leaks cause pressure drops that trigger pick-and-place vacuum errors.
  • MandateTarget:: Scan all overheadOverhead distribution lines and regulator dropsdrops.
  • Frequency: semi-annually.Semi-Annual scan.

• Nitrogen (N2) Reflow Plumbing:

  • Target: N2 is a significantdirect operationalcost cost.of goods sold (COGS). Leaks inhere compromise the reflow oven plumbing compromise inert atmosphere integrity.
    and increase solder defects.
    • MandateIf: ScanUltrasonic reflowSignal oven N2 plumbing quarterly. Any leak generatingis > 10 dB overabove background noise-> mustThen be taggedTag and sealed.Seal.

  Motor Current Analysis (The Load)

  Monitoring the currentCurrent draw ofis a direct proxy for mechanical load. A conveyor motorsmotor andpulling pick-and-placehigh headsamps providesis earlyfighting warninga ofjam mechanicalor binding.a seized bearing.

  • BaselineBaseline:: Establish a "Golden Trace" offor currentnormal draw during a standard cycle.operation.
  • DeviationIf:
    • Elevated Baseline shifts Upward: Indicates-> frictionThen (lack of lubrication,Check belt tension tooand high).lubrication.
    • Spikes: Indicate jamming or physical obstruction.
  • MandateIf: ConveyorCurrent systemsSpikes must> have120% -> Then Trigger PLC "Over-Torque" limitsShutdown.
    • Logic: setCut inpower before the PLCmotor toburns cutout poweror immediately if current exceeds 120% of nominal load, preventingthe PCBA crashis damage.crushed.

  Final Checklist

  TechnologyParameter	AssetMetric Class/ Rule	MonitoringCritical Freq.	Action ThresholdState
  Vibration Limit	ReflowISO Blowers	Monthly10816-3	> 4.5 mm/s RMS
  VibrationReflow Fans	WaveCheck ImpellersFrequency	Monthly
  Electrical Heat	MonthlyDelta T (Phase-to-Phase)	> 4.520˚C mm/s= Shutdown RMS
  ThermographyMotor Heat	ElectricalHousing Panels	AnnuallyTemp	> 5 80˚C Delta-T
  ThermographyN2 Leaks	Motors/Gearboxes	Quarterly	>Ultrasonic 80 C Housing
  Ultrasonic	N2/Air Lines	Semi-AnnuallyThreshold	> 10 dB Signal
  CurrentConveyor Protection	Conveyors	ContinuousCurrent Limit	> 120% Nominal
  Scan Schedule	Electrical IR	Annual