The use of a new recipe management system from a single source and the addition of hopper scales for batching extend process control functions and reduce production downtimes in a large bakery.
Albany Bakery, a large consumer goods company in South Africa, requested an upgrade of its process automation equipment for its baking operations in Germiston, South Africa. In the dispensing and dough-mixing area, additional Sartorius weighing hoppers – hopper scales – were installed, and a new Sartorius recipe management and control system was set up. Besides PR6246 tension load cells, ProBatch+ recipe management software linked to Combics Pro controllers was installed. This solution ensures added process reliability and ease of operation. Remote diagnostics and support are provided via an Internet connection.
The customer’s operators appreciate the user-friendly display of the Combics Pro.
The Germiston bakery manufactures sliced bread on three fully automatic production lines (two lines producing 6,000 loaves per hour and one 5,000 loaves per hour). Currently, raw materials, such as flour, water, ice cubes and yeast, from seven bulk flour storage silos and one on-site cream yeast plant are fed into the production lines. These ingredients are weighed in according to the recipes using 13 hopper scales total, and the typical batch size is 330 kg. From there, five dough mixers are fed. All of these dough-mixing stations are controlled by batch controllers linked to programmable logic control units (PLCs). The batch controllers evaluate the weighing signals transmitted by the hoppers and execute the recipes. Physical control of the valves and pumps in the process is handled by the PLCs.
The batch management system already available at the bakery plant needed a hardware upgrade to ensure reliable dough-mixing process operations. Moreover, additional bulk raw materials (ice cubes and cream yeast), which had been added manually until now were to be included in the automatic batching process. This required an extension of the process weighing equipment and software facilities. For Albany Bakery, ease of operation and after-sales support for this installation were essential requirements.
Plant 1 and plant 2 with their weighing hoppers connected to the storage silos.
To implement the new concept, most of the obsolete control equipment was removed and replaced by PCs, PLCs and weighing controllers. A combined solution of five PLCs and three Probatch+ recipe management systems networked to eight Combics Pro series controllers was chosen for control of raw material storage, feeding and mixing. For weighing, the existing 13 hopper scales already equipped with PR6246 tension load cells were integrated into the new process environment. This solution features a modular design that is easy to tailor to meet the customer’s specific requirements.
The Combics Pro controllers transmit weighing signals to the PLCs and execute sequential recipe lines sent by the Probatch+ software system. The equipment selected included Sartorius weighing controllers as field control terminals because they are capable of monitoring two real weighing points, plus flow meters for dispensing yeast. These flow meters were taken over from the old control equipment setup and are now connected to the PLCs so that yeast dispensing is included in the automatic batching process.
Control and interlocking of the field devices are executed by the PLCs, which communicate with the Combics Pro controllers via a Profibus network. The Probatch+ software was selected based on its design and capacity to manage several production lines for this large bakery plant. The software is ideal for editing recipes and production plans and for running production operations from personal computers linked to the plant network.
The production systems are operated using touch-screen monitors that are each mounted locally per mixer station. On the local monitor, the operator just enters commands he or she is authorized to use, such as component set points and batch sequence requirements. Production can also be started or stopped from the touchscreen terminals. Plant managers have access to other control functions only from the Pro Batch+ or Combics Pro terminals. Redundancy is designed into the automation solution so that production for a given bakery plant can be moved from each Probatch+ installation to another in the event of a computer failure.
The Sartorius load cells for batching had already been in service for nearly 20 years on the flour and water hopper scales and still have been delivering the same high performance ever since. These PR6246 tension load cells provide excellent resolution and accuracy in a process environment. As a result of their special S-shaped design, they feature high signal sensitivity and therefore accurately respond to slight load changes. Thus, these load cells were retained along with the available hopper scales, and five additional automatic scales with new load cells were installed and connected to the new Combics Pro controllers.
The most important benefit for the customer is increased process reliability provided by the upgraded recipe management system. This new installation provides Albany Bakery with a state-of-the-art, fit- for-purpose batching solution designed to provide years of reliable service. In addition, this new technology solution enables convenient remote technical support via an Internet connection. Beyond these advantages, the new equipment solution integrates all bulk raw materials into one control and reporting environment, which was not possible before with the former equipment.
Moreover, Sartorius was able to offer exceptionally fast installation schedules where only one bread production line had to be shut down during installation and commissioning of the new equipment. In the interim, both old and new systems remained up and running.
"The new process management system is an outstanding achievement! Our colleagues can now manage and control all batching processes using one recipe software program in the control room.”
Pieter Broodryk – National Engineering Manager
The Germiston bakery plant receives its essential bread ingredients by truck.
About the Customer
Albany Bakery is a branch of the Tiger Brands Group, which is a fast-moving consumer goods giant in the South African market.
Headquartered in Germiston, South Africa, the company was founded in 1983 and today is considered the largest bakery in the Group.
This bakery produces an extensive range of high-quality bread products, which have gained a strong brand presence and customer loyalty through the company’s use of innovative products and manufacturing technologies.