TL;DR
Weight deviations in a rotary packer usually come from aeration air pressure drift or a fouled fill head valve. Verify aeration pressure and clean the fill head before adjusting the dosing setpoint.
What you might see
- bag weights consistently above or below target
- high reject rate from the checkweigher
- fill spout air pressure fluctuating
- fill rate slower than rated throughput
Likely causes
Aeration air pressure below the specified value reducing fluidization of the cement
Fill head valve worn or contaminated with hardened cement restricting the dose
Weighing load cell contaminated with dust affecting tare and live weight accuracy
Bag seat not fully seating on the spout allowing air leakage during fill
Required tools
- Calibrated floor scale for verification
- Pressure gauge for aeration air
- Cleaning brush and compressed air
- LOTO kit
Safety first
- Cement dust is a respiratory hazard. Wear P100 respiratory protection when working near fill heads.
- Cement dust explosion risk in confined spaces. No hot work near the packing line without a permit.
Procedure
- 1
Lock out the packer drive and air supply before any maintenance on the fill head.
Warning: Cement dust is a respiratory hazard and in certain concentrations an explosion risk. Wear P100 respiratory protection when working near open fill heads. - 2
Check the aeration air pressure at the fill spout inlet. Compare to the specification on the machine nameplate.[1]
- 3
Remove the fill head and inspect the valve seat and body for hardened cement buildup. Clean with compressed air or a brush.[1]
- 4
Check each load cell mounting for dust buildup or mechanical interference. Clean the load cell surroundings and verify zero tare reads correctly.
- 5
Inspect the bag seat rubber spout seal for wear or cracking. Replace if worn.
- 6
Run a sample fill of 10 bags and weigh each on a calibrated floor scale. Compare results to the checkweigher.
- 7
Adjust the dosing setpoint only after confirming the aeration, fill head, and weighing system are all functioning correctly.
Sources
Haver & Boecker Haver Roto-Packer ROTO Cement Bagging Machine general technical documentation, Haver & Boecker
Haver & Boecker packing machine operation and maintenance documentation, fill head and weight adjustment procedures (general)
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