TL;DR
Temperature control faults cause under- or over-mixed compound and scorch risk. Verify the temperature controller setpoint, rotor coolant flow, and thermocouple continuity before adjusting mixing time.
What you might see
- batch dump temperature above specification
- temperature controller alarm active
- rotor or chamber thermocouple reading erratic
- cooling water temperature differential across the rotor lower than expected
Likely causes
Thermocouple failed or drifted causing incorrect temperature feedback
Rotor coolant flow insufficient from a blocked water circuit or pump fault
Temperature controller setpoint incorrect for the compound being mixed
Scale buildup in the rotor cooling channels reducing heat transfer
Required tools
- Multimeter for thermocouple resistance check
- Replacement thermocouple (matching type)
- Cooling water flow meter
- LOTO kit
Safety first
- Lock out the mixer drive and hydraulics before removing the thermocouple from the chamber. The ram can drop without warning.
- Hot compound in the chamber can scorch or ignite if temperature control is lost. Do not run a batch with a known faulty thermocouple.
Procedure
- 1
Check the actual batch temperature on the controller against the thermocouple reading. If they diverge, suspect a thermocouple or extension wire issue.[1]
- 2
Lock out the mixer and remove the thermocouple from the mixing chamber. Check the thermocouple resistance and compare to the known-good resistance range for the thermocouple type.[1]
- 3
Measure the coolant flow rate in the rotor cooling circuit using the flow indicator or rotameter. Compare to the specification.
- 4
Inspect the cooling water supply temperature at the cooling system heat exchanger outlet. The supply temperature must be below the required cooling capacity limit.
- 5
If coolant flow is low, check for scale buildup in the rotor cooling channels by pressure-testing the circuit. Descale per the Farrel-Pomini descaling procedure if needed.
- 6
After repairs, monitor the batch temperature on the next three mixing cycles and compare to the specification.
Sources
Farrel-Pomini Farrel BR / F-Series Rubber Banbury Mixer general technical documentation, Farrel-Pomini
Farrel-Pomini Banbury mixer temperature control and cooling system maintenance documentation (general)
More guides for Farrel-Pomini Farrel BR / F-Series
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Drop door hydraulic faults prevent batch discharge and can cause compound to degrade in the chamber. Check hydraulic pressure, door seal, and door latch solenoid before forcing the door open.
How to fix rotor seal leakage on a Farrel-Pomini BR / F-Series Banbury mixer
Rotor end seal leakage contaminates the batch and allows compound to escape the mixing chamber. Replace the rotor seals before leakage reaches the drive side bearing, which is much more expensive to repair.
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