Belt Weigher Troubleshooting: Causes & Fixes

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Problems on this page:

Totals do not match the stockpile or ticket weights Zero drifting Speed signal faults Reading affected by belt tracking Load cell or electronics fault Errors at low or high belt loading Material spillage at the weigh area Calibration not holding

Totals do not match the stockpile or ticket weights

Hits OEE: Quality

Symptoms: The belt weigher total disagrees with truck or batch weights.

Weigher not calibrated

Calibrate with test weights or a test chain and check with a material test.

Belt tension changed

Keep the take-up tension constant.

Weigh idlers out of alignment

Align the idlers in the weigh area precisely.

Zero not set on an empty belt

Run the automatic zero on the empty belt.

Prevention: Zero and span checks on a fixed schedule with the results logged.

Zero drifting

Hits OEE: Quality

Symptoms: The reading on an empty belt changes over the day.

Material build-up on the weigh frame

Clean the weigh frame and idlers.

Belt with uneven weight

Use a belt profile zero where the belt varies.

Temperature changes

Re-zero after warm-up.

Load cell damage

Check the load cell.

Prevention: Zero checked at the start of each shift.

Speed signal faults

Hits OEE: Quality

Symptoms: Rate or total reads wrong because the speed sensor is not reading.

Speed wheel slipping on the belt

Check the wheel contact and position.

Sensor wiring damaged

Repair the wiring.

Speed sensor on a slipping pulley

Mount the sensor on a non-driven pulley.

Sensor dirty

Clean the sensor.

Prevention: Speed reading compared with a measured belt speed monthly.

Reading affected by belt tracking

Hits OEE: Quality

Symptoms: Accuracy changes when the belt runs off centre.

Belt mistracking through the weigh area

Track the belt so it runs centred.

Training idlers in the weigh area

Keep training idlers away from the weigh area.

Skirting touching the belt

Adjust the skirting.

Load off centre

Centre the load at the loading point.

Prevention: Tracking checked at the weigh area weekly.

Load cell or electronics fault

Hits OEE: Availability

Symptoms: The weigher shows an error or no reading.

Water in the junction box

Seal and dry the junction box.

Load cell overloaded

Check for impact loads and fit overload stops.

Cable damaged

Repair the cable.

Integrator fault

Check the integrator.

Prevention: Junction boxes inspected after washdowns.

Errors at low or high belt loading

Hits OEE: Quality

Symptoms: Accuracy is good at normal rates but poor when the belt is lightly or heavily loaded.

Weigher outside its working range

Check the design range against the actual rates.

Linearity not set

Calibrate at more than one load.

Belt too stiff for light loads

Check the belt and the idler spacing.

Surges at the loading point

Even out the feed.

Prevention: Material tests at different rates.

Material spillage at the weigh area

Hits OEE: Quality

Symptoms: Product falls on the weigh frame and affects the reading.

Loading point too close to the weigher

Move the weigher away from the loading point.

Skirting worn

Replace skirting.

Belt overloaded

Reduce the feed rate.

Scrapers worn causing carryback

Fix the scrapers.

Prevention: Weigh area cleaned on the daily round.

Calibration not holding

Hits OEE: Quality

Symptoms: Accuracy drifts soon after each calibration.

Mechanical cause not fixed

Find and fix the build-up, misalignment or tension change first.

Test weights or chain not certified

Use certified test equipment.

Calibration done with a dirty belt

Clean before calibrating.

Weigh frame moving

Check the frame mounting.

Prevention: A calibration record showing results before and after adjustment.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: conveyor · checkweigher · screw conveyor · bucket elevator · crusher · load cell · concrete batching plant

Stop the same fault coming back

Recurring belt weigher stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover