Automated Bag-Filling Weighing Solution Using Load Cell Technology

A manufacturer approached BONNER for support with a weighing challenge on a new automated bag-filling machine. The machine dispensed a viscous material, but the output was not consistent enough to reliably determine the final weight of each bag.

Manual weighing was also awkward and difficult to carry out cleanly within the production process. The manufacturer needed a solution that could measure the actual weight of the bag during filling and use that measurement to trigger the machine to stop once the required target weight had been reached.The application needed to accommodate product weights ranging from approximately 0.6 kg to 4.5 kg gross, with potential future requirements of up to 6–7 kg. It also had to integrate with the existing machine controls, including a 24 V signal requirement.

BONNER worked closely with the client’s engineering and maintenance teams to assess the application and identify a suitable weighing arrangement.

Following an initial remote assessment, BONNER arranged a site visit to inspect the machine, take measurements and evaluate the available mounting options.

This assessment identified a critical consideration: the dispensing pipe could make contact with the weighing arrangement, introducing additional forces that could affect measurement accuracy. An initial concept explored using two S-beam load cells to accommodate the physical arrangement. Following modifications to the dispensing nozzle, the team refined the design towards a single calibrated S-beam load cell, simplifying the weighing system and avoiding the need to synchronise two sensors.

The recommended solution incorporated:

BONNER also advised on the mechanical mounting arrangement, highlighting the importance of applying the load vertically to help maintain measurement accuracy. The amplifier could be configured and calibrated before shipment, with provision for a zero adjustment after installation.

Selecting a suitable load cell was only one part of the challenge. The physical arrangement of the dispensing nozzle, bag support and weighing equipment had to be considered alongside the electrical and control requirements. By assessing the machine in its actual operating environment, BONNER helped identify potential sources of measurement error before finalising the recommended arrangement. The revised approach was developed around the client’s equipment and requirements, rather than relying on a standard component selection alone. This application-led process brought together weighing technology, calibration, mechanical considerations and control-system integration to support a practical solution for automated filling.

• Improved fill-weight control

Measuring the bag directly allows the machine to use actual measured weight as the stopping point, rather than relying solely on the dispensing system’s existing counter.

• A more practical weighing process

Integrating weighing into the machine can reduce reliance on separate manual weighing and help streamline the filling operation.

• Flexibility for different product weights

The selected arrangement considered current product weights and potential future requirements, providing flexibility as the application develops.

• Simplified system design

Moving to a single calibrated S-beam load cell reduced the complexity of the proposed arrangement and avoided concerns about synchronising multiple sensors.

• Support for material efficiency

More controlled filling has the potential to reduce overfilling and unnecessary product giveaway, helping minimise material waste.

• Technical support beyond product supply

BONNER’s involvement included application assessment, product selection, calibration planning and consideration of the interface with the existing machine controls.