the use of an automation system and its generation of records and date should be used not only to just make feed, but also to make decisions regarding employee training, equipment efficiency, and to increase business profitability
By Wilmer Pacheco, Adam Fahrenholz and Charles Stark
Having the opportunity to attend another International Production and Processing Expo (IPPE) in Atlanta has made me think about how the feed industry has evolved in recent years. At IPPE, attendees have the opportunity to learn about new equipment, tools to generate data, and advances in equipment automation. Feed mills use automation to increase productivity, reduce labor costs, reduce errors, and generate records for regulatory compliance. Furthermore, an automation system can be used to collect inventory records of ingredients and finished feeds, handle lot number tracing, and track scale variations. These records can be used for compliance with the Food Safety Modernization Act (FSMA), Hazard Analysis Critical Control Point (HACCP), and other state or federal rules or voluntary programs.
The automation system uses personal computers (PCs) as clients, as well servers and programmable logic controllers (PLCs) to operate equipment and collect information from sensors throughout the feed mill. The client PCs are typically located in a control room or sealed cabinets if in the production area, while the PLCs and servers are typically located in communications closets or motor control centers. Operators use the client PCs to monitor each process and to input information and commands. The server collects the input information and sends instructions/commands to the PLC responsible for executing the task (e.g., start/stop equipment, open/close gates, activate vibrators, stop the source, etc.). The PLC also receives inputs from motors, thermocouples, load cells, and other devices throughout the facility. After the PLC receives inputs from the operator and/or sensors, signals (outputs) are sent to start a route, to increase or decrease feeder speed via a variable frequency drive (VFD), or shut a gate once a task is completed.
Automation can be present throughout an entire facility or may focus on a single process area subsequent to a renovation of an older mill. The first process that may be automated is also the first process in the production flow: receiving. Once the operator determines the destination of an ingredient (and potentially performs verification steps such as quality evaluation, purchase order verification, etc., depending on the level of system sophistication) the automated system will activate conveyance equipment (e.g., drag conveyors, augers, bucket elevators, etc.) to move the ingredient from the receiving pit to a storage bin.
Batching and mixing was one of the first processes to be automated due to the high volume of ingredients handled in a feed mill, the number of scales opening and closing, and the necessary routing control of mixed feeds. One of the main advantages of automation is the flexibility to make immediate changes in manufacturing processes. During a feed mill visit, I observed that the major and minor scales were opening at the same time, which poses a risk of minor ingredients entering the mixer first, accumulating in the bottom, and leading to poor mixer uniformity; however, this was easily corrected by implementing a 5 second delay in the minor scales’ discharge. This simple adjustment was easy to make and did not affect batching and mixing efficiency from the standpoint of cycle time. An automated batching process can also be valuable due to the ability to export formulas from a least cost formulation system. While formulas can also still be entered from a hard copy, the export/import feature can save time and reduce the chance of input error. An automation system also impacts efficiency by allowing batching operators to schedule the order of feed manufacturing, determine the number of batches, and set the destination of mixed feeds. From that point, the system can automatically route the feed to the correct bin and switch between multiple bins if one bin gets full. An automated system can also be used to sequence and restrict the manufacturing order based on medication types using a predefined order established by the feed mill manager or nutritionist. In the batching area, the automation process has helped to remove workers from dusty environments and has reduced the manual weighing of ingredients. Therefore, in addition to improving efficiencies, automation has also improved occupation safety and health and reduced work-related injuries.
The pelleting system requires a higher level of automation due to the number of inputs (e.g., thermocouples and motor loads) and outputs (e.g., VFD’s, steam valves, air cylinders on dump chutes) being monitored and controlled. The operator can define parameters such as the initial feeder speed, steam valve opening, motor load, target conditioning temperature, and tons/hour. This information is used by the automated system to execute and monitor the pelleting process. Under fully automatic operation, the pellet mill system can control steam addition to reach a target conditioning temperature and the feeder rate to achieve a desired production rate or pellet mill motor load. During cooling, VFD drives on the top and bottom decks of horizontal coolers can control deck speed and pellet bed depth. In counter-flow coolers, the duration of grid opening, pellet bed depth, and air flow can be controlled to reach desired moisture and temperature in pellets exiting the cooler.
The automation system can also be used to generate feed mill records at a pre-defined frequency. Some of these records can include: equipment motor loads, conditioning temperatures, batch reports, production rates, and inventory variances. These records can be used to evaluate the operator’s efficiency and find opportunities to improve various manufacturing processes.Some feed mills can use records and trends to estimate the root cause of a particular problem, prioritize tasks, and define action plans to correct issues. For instance, if a feed mill struggles to maintain good pellet quality, the records generated can help to track and evaluate the factors we know to be associated with poor pellet quality. Such factors might include: amount of mixer added fat, throughput, conditioning temperature and/or retention time in the conditioner, retention time in the cooler, etc. Feed mill managers and operators can utilize records to identify and trend which factors are having the highest negative effect on pellet quality and can focus on resolving the issue. Records can also be used to identify if a process is stable and predictable over time. For instance, a highly variable motor load in the pellet mill can lead to inferior pelleting efficiency. The root cause of this problem could be inadequate filling of the conditioner, which can lead to uneven addition of moisture and heat, poor hydration of feed particles, or inconsistent mash feeding into the pelleting chamber.
Taking all the above into consideration, it is also important to realize that an automation system requires employee training, just as any other part of the feed mill. Once again, taking the pelleting area as an example, sometimes operators feel more comfortable controlling the pelleting system manually by increasing/decreasing feed rate (feeder speed) or opening/closing the steam addition valve to accomplish a target conditioning temperature and motor load. However, the automation system has been designed to control these variables automatically, and thus operator training on how to properly utilize the system may needed.
Overall, the use of an automation system and its generation of records and date should be used not only to just make feed, but also to make decisions regarding employee training, equipment efficiency, and to increase business profitability.
