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MAINTENANCE | Essential Steps for Melt Pressure Transducer Calibration

Representative calibration image


Quick Guide: Melt Pressure Transducer Calibration


Audience: Maintenance Leadership

Goal: Get the extruder back up fast with accurate pressure readings

Time Required: ~5 minutes (if no issues)


BEFORE YOU START – Quick Checks

  1. Is the transducer installed and wired properly?

    • Mounting torque correct (usually 100–200 in-lbs)?

    • Connector tight?

    • Wiring verified? (No shorts/opens)

  2. Is the extruder barrel at operating temperature?

    • Cold barrel = bad readings

    • Never calibrate a cold transducer


CALIBRATION PROCESS


STEP 1: ZERO CALIBRATION (No Pressure in the System)

You MUST do this before material flow starts.

  1. Power up system – wait 2–3 minutes for sensor to stabilize.

  2. Ensure there is no pressure in the barrel (vent open, no backpressure).

  3. Zero the transducer:

    • On the amplifier, PLC, or HMI: hit “ZERO” or “TARE”.

    • If using a digital readout, it should now display 0 psi / 0 bar.

✅ If zero won’t hold, check wiring or sensor damage.


STEP 2: SPAN (OPTIONAL – ONLY IF REQUIRED)

Usually factory-set. Skip unless you’ve replaced the transducer or readings seem off.

  1. Use a simulator or pressure calibrator (if available).

  2. Apply known pressure (e.g., 1000 psi).

  3. Adjust span on the display/controller to match applied value.

✅ If span is off and can’t be adjusted, sensor may be faulty.


STEP 3: VERIFY UNDER LOAD

  1. Start material flow.

  2. Monitor pressure readings under typical extrusion load.

  3. Compare with expected range – if it looks wrong:

    • Double-check zero

    • Compare to backup gauge (if installed)


TROUBLESHOOTING – FAST FIXES

Symptom

Possible Cause

Quick Fix

Stuck at max or min value

Broken sensor or wiring issue

Swap with known good sensor

Won’t zero

Pressure still in system / damage

Vent barrel / replace sensor

Fluctuating signal

Ground loop / EMI / loose wires

Check shield, reroute cables

Reads zero under pressure

Span off or wrong range sensor

Check calibration / specs

 TIPS TO KEEP MOVING

  • Keep a spare transducer on hand.

  • Use quick-disconnect cabling if possible.

  • Don’t calibrate until system is at temp and pressure-free.

  • Document calibration date & operator for traceability.

 

Always consult your process management team for FORMAL process steps / these tips are for consideration and to start the conversation!


 
 
 

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