Mixing control for bakers

Baker Perkins has developed a new control system for Tweedy mixing systems - now renamed Tweedy2. Plant bakers using this definitive system for the Chorleywood process will benefit from improved consistency and quality of the baked product, plus enhanced efficiency and ease of use.

The new controls cover all the elements of a fully integrated Tweedy mixing system: ingredient handling and weighing, mixing and tub hoist. The reliability and performance of the existing Tweedy have been retained by carrying over to the new system its process, mechanical and electrical attributes. This will also allow the new controls to be retrofitted to existing Tweedy installations.

The operator interface is a touch-screen HMI that provides clear, at-a-glance visualisation of the process with easy and intuitive operation, using graphical button labels wherever possible.

Fault finding is enhanced by filtering of alarms to display the primary cause of a stoppage but not the consequential alarms, which significantly reduces the time needed for operators to identify and rectify a problem. Process alarms alert operators to potential variations that can affect the dough and enable them to prevent stoppages downstream.

Operationally, a major gain is more immediate updating of all recipe and process settings. Changes can be made up to the moment mixing starts: conventionally there may be up to a two-mix delay while settings are amended. The benefits of any changes needed to improve product quality or plant efficiency are thus seen immediately.

Plants with multiple mixers now share a common schedule and act as an integrated system in order to complete it. Schedules are dynamically optimised to maximise plant output while ensuring that there are no delays in using dough, which might cause quality or downstream operational problems. Centralised uploading of recipes saves time and reduces errors.

Improved reporting includes aggregated ingredient usage data; real-time and historical trending of key parameters such as mix time, energy, temperature and pressure/vacuum; and a comprehensive alarm database. This information is useful for both real-time operation of the mixer and for long-term process improvement programs. All the stored data is easily accessible by higher-level systems such as SCADA, ERP or PC networks.

Software has been developed for three major hardware platforms - Rockwell Compact Logix, Mitsubishi Q Series and Siemens S7 - but can be supplied for other platforms if necessary. All software is structured to the latest international standards to enable it to be readily understood by any software engineer and reduce the time needed for troubleshooting and maintenance.