Bakery batching systems are considerably more simple than their Feed Mill batching system counter parts. In this application we implemented multiple batching stations. Usually there would be a single batching station. This customer application was provided with three batching stations using a single Allen Bradley PLC controller. They have two areas, entitled the “Frozen” and “Par” lines.
The “Frozen” area as they call it only has one batching station but it is expandable to add a second batching station. The “Par” line has two batching stations which share flour, oil, and water as their bulk ingredients. Multiple batching stations for the total system to provide convenience and operator flexibility. Typically, with the exception of water, when each batching station makes a call for flour or oil, the PLC service each request as first come first serve (FIFO). Flour is conveyed pneumatically and oil is pumped to either mixer available. Water, however, can be tempered or chilled. Water going to each mixer can be called at any time without waiting for the other to finish because each mixer has a dedicated flow meter for each type of water that is monitored to meter how much water goes into the mixer.
The Batching screen shows a flour scale mixer, and liquid meters. When the equipment or vessel is on or active the graphic will go from dark gray to bright white. If an alarm exists on any equipment, a red square surrounds the device with a pulsating red triangle. Each batching vessel has a batch block as described earlier but includes ingredient and bin information. The text that shows status are color coded indicating any abnormal condition as red, normal operation as green, waiting condition as orange, or idle condition as black. Each ingredient bin above each scale shows calculated level as a narrow bar graph and they are color coded as well. The color coding is determined by the level set points and bin inventory in the bin assignment table . The bar graph will be blue if above the warning set point, yellow if between the warning and low set point, and red if below the low set point. Each scale has a scale gauge that shows the target set point and net amount underneath. A green band on the gauge is the graphical representation of the target weight set point. The needle will move closer to the green band as the scale hopper fills. The modern touchscreen graphic display conforms to ISO 11064, ISA101, ANSI, and ASM standards and practices.
The second part to the batching system is mixer controls. Our batching stations do not directly control the mixer operators but we send mixer speed references and flour slide gate open/close commands to a separate controller. The mixer controllers and their programming were supplied by a different vendor. This other vendor has Allen-Bradley PLC mixer controllers at each of the multiple batching stations and the batching stations communicate with the mixer controllers over the Ethernet/IP network. They also send us status and alarm conditions that we display and notify on our HMI. Once we finish each batch cycle, the mixer operator takes control to tilt the bowl down and “kick” the dough out into a trough. Pizza crust and flat bread is the end product made at the customer plant.
Hand adds were also a part of the overall batching system. Hand Adds and Premix’s are prompted and can be acknowledged from the batching stations. Hand adds and Premix’s shown on the main screen will look like that shown to the left.
One unique aspect of this project, compared to others we’ve done, is that commissioning of both the “frozen” and “par” lines were done remotely due to COVID19 restrictions imposed by the customer and Sterling Systems to protect all employees. Sterling Systems, two electricians, the customer, other contractors, and customer IT people worked together on various occasions from installation questions, IO checkout involvement, equipment configurations and setup, to training. The “frozen” line system was commissioned in April and May of 2020 and has been in production ever since. The “par” line system was commissioned in August 2020.