The new controls cover all the elements of a fully integrated Tweedy mixing system: ingredient handling and weighing, mixing, and tub hoist.
The unrivalled reliability and performance of the existing Tweedy have been retained by carrying over to the new system its well proven 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. Another new feature is process alarms, which alert operators to potential variations that can affect the dough and enables 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 programmes. All the stored data is easily accessible by higher level systems such as SCADA, ERP or PC networks.
Engineering improvements include the use of a modular software structure that conforms to the latest international standards. All the modules are fully pre-tested and are designed to enable systems to be readily configured for individual installations without bespoke code being required. This risk-free structure reduces installation and commissioning time and makes both maintenance and future upgrades extremely straightforward.
A further benefit of the modular approach is that automatic self-test routines, written by Baker Perkins to reduce commissioning times, can be used by customers to reduce downtime after maintenance work. Installation time is also significantly shortened by reducing wiring through the use of distributed I/O.
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 trouble shooting and maintenance.
High efficiency in terms of mixing performance and reliability, and low cost of ownership, are key reasons why the Tweedy is the mixer of choice for leading industrial bakers utilising the Chorleywood process, particularly in the UK and Ireland, South Africa, Australia and New Zealand.
