press_mechanical — temperature (rtd-motor-bearing)
Physics
Section titled “Physics”A mechanical press’s main drive motor bearing generates frictional heat continuously while running; a developing defect (loss of lubrication, race pitting, misalignment) increases friction and raises the bearing’s steady-state operating temperature above its healthy baseline, and a sudden lubrication failure causes a fast rate-of-rise rather than a slow drift, matching the press-floor maintenance-log pattern of “noise from the press motor bearing” preceding a bearing failure. A PT100 resistance temperature detector (RTD) bonded or strapped to the bearing housing tracks this via its resistance-temperature relationship, read through a transmitter that outputs a linearized 4-20 mA or digital signal. Bearing housing thermal mass gives the temperature a time constant on the order of minutes, not seconds: a step change in friction takes several minutes to show up fully at the housing surface, so there is no benefit to sampling faster than the thermal physics can move. Sampling the RTD/transmitter at 1 Hz resolves the fastest realistic rate-of-rise for a developing bearing failure (typically well under 1 degree C/second) with large margin, while keeping the data volume reaching the historian small; the edge node reports 1 Hz readings directly (no further reduction needed for a signal this slow).
Sensor
Section titled “Sensor”- Spec: PT100 RTD probe with 4-20 mA or digital transmitter, surface/bolt-on or threaded-well mount
- Signal: scalar (Cel), range n/a
Example parts
Section titled “Example parts”- Omega Engineering PR-13 series PT100 surface-mount RTD probe with bolt-on bearing clip
- ifm electronic TA2585 temperature sensor with integrated 4-20 mA transmitter (-25 to 125 degC)
- Pepperl+Fuchs KT-SR2-* temperature transmitter paired with a PT100 surface probe
Mounting
Section titled “Mounting”Bolt or strap the RTD probe’s bearing clip directly onto the motor’s outboard bearing cap/housing, on bare clean metal for good thermal contact, as close to the bearing race as the housing geometry allows. Insulate the exposed probe tip from ambient airflow with a small thermal-insulating boot if the housing is in a drafty location, to avoid a false low reading.
Wiring
Section titled “Wiring”3-wire or 4-wire RTD lead wire from the probe to the transmitter (minimize lead-wire resistance error by keeping runs short or using 4-wire), then the transmitter’s 4-20 mA or digital output to an analog/digital input on the edge box’s I/O module, routed away from the motor starter’s power conductors.
Validation
Section titled “Validation”run the press through a normal production shift and compare the detector’s logged bearing temperature trend against a handheld infrared thermometer reading taken at the same housing location at the start, middle, and end of the shift
Expected: detector reading within +/-3 degC of the handheld reference at each spot check, with no missed rise above high_c during the shift
Safety notes
Section titled “Safety notes”- de-energize and lock out the motor starter circuit (LOTO) before opening the motor terminal enclosure or drilling/tapping the bearing housing to fit the probe clip
- the bearing housing is a hot-surface burn hazard during and immediately after running; let it cool or wear heat-rated gloves before direct contact
- verify the transmitter’s supply voltage and signal wiring rating before connecting it near motor starter power conductors
60–250 USD, difficulty 2/5, ~25 min install downtime.