Another benefit a DCS brings to the table is that it allows the plant to use cascade loops to control entire production systems. The loops use the data to produce live trend charts of different portions of a system or the whole process. This allows an operator to predict where the system is going and make adjustments early. During my manufacturing days we would say this was the best situation because the operator is running the process and not the process running the operator. Typically, in this situation operations groups are looking forward at least 12 hours, allowing them to make small changes and causing minimal impact on the system.
Another consideration is that programming remote PLCs is logistically more challenging in the plant atmosphere versus programming and updating a DCS. The DCS providers have advanced to a point where programming a system, tuning an instrument, or building a human machine interface (HMI) faceplate is all Windows-based, efficient and can be done remotely. This allows a company to centralize their controls group to one location or even utilize a third party to handle those tasks. When a plant is located in potentially remote or inhospitable areas of the country it can be challenging to find staff for these types of positions.
FE: If you start out new with a single vendor’s equipment in a line, the integration process becomes easier, right? What are the benefits/tradeoffs of this approach?
MB: When working with a single vendor for a production line, it often simplifies the installation and coordination between the equipment in the line. Now one of the challenges can be if the vendor can provide you with instruments, programmable logic controls (PLCs) and controls hardware that matches or can communicate with the existing plant equipment and/or DCS. Special attention needs to be taken to ensure that their equipment provided can communicate to the existing systems and to what degree you have control with that existing DCS.
Further some vendors have proprietary programming and software that is completely locked down. If you need to make changes to the system you have to use that vendor’s instrument and controls group even in emergency failure situations. It is also very important to understand what equipment they do not manufacture and are buying out in the process. Down the road, it can get complicated if there are issues with that third party equipment service and possible warranty work.
Another consideration would be that in dealing with only one vendor for a whole line of equipment, there is only one group responsible. Your communication channels can be very efficient with only one point of contact. It should be noted that you should always request a single project manager from the vendor since large equipment vendors have multiple manufacturing sites and as an owner you do not want to have to deal with each site for the equipment they make.
One final thought is that your plant or company may not have a large procurement department. Purchasing many different pieces of equipment from multiple vendors, and each with its own terms and communication channels, can easily bog down a small procurement department.
FE: I once visited a yogurt facility where it seemed the only remaining step in an otherwise totally automated plant was to automate removing the cups out of the cartons they came in and placing them in the filler. How do you help clients integrate/automate that one last step?
MB: For the example you described, the approach is not any different than most other design projects. You need to first agree on a charter that defines exactly the goal of the project, in this case, automating container delivery. The charter should also define the budget, any client-required design aspect, project completion date and capacity requirements.
Next, the group will need to identify the current control system type and the proper protocols and software that allow for communications and control of the new equipment. Vendors will need to be identified that can provide the equipment needed to perform the task and meet required build specifications.
The design engineers will work with controls experts to identify the proper specifications with the vendors design team to ensure the unit specified can be integrated properly with the current system. Quite often the reason a piece of equipment or task has not been automated is due to the cost or lack of available technology at the time of original installation. Then after a few years, technology advances and reduces the cost of the device, or a device is invented to perform the task. Things are constantly evolving and improving in automation.
FE: Most food companies will have some sort of ERP/business software in place. But, we haven’t said much about software. What should be in place beyond local machine control(s)? HMI? Historian? Process/batch control, MES? What would be the bare minimums required for integration?
MB: A successful fully automated facility has an overarching DCS from one of the many capable companies in place. You should always have a historian installed as it gives you several important capabilities. Such capabilities include allowing plant personnel to trend back hours, days, weeks or even years on each specific instrument that is being historicized. Another important aspect is that it allows a more automated system for product traceability and, if needed, identifies product recall needs. Without a historian, a food plant depends on paper records for tracking and tracing products. Paper takes a lot of time and room to store, protect, label and file. If there is a potential recall event, time is of utmost importance, so a historian allows very quick data retrieval.
HMI’s are integral to field monitoring equipment and it is common for most major equipment, like palletizers, check weighers, container fillers, packaging, etc., to come with their own vendor supplied unit. It is important that the vendor unit can communicate via Ethernet to the plant’s overall system and if possible, having the same look and feel of the graphics. With a DCS you typically have centralized control rooms where there is a large bank of control monitors. When cascading systems together, it is important to have both control screens showing the actual process running with control points, but also a screen available to display charts and trends of the process. These trend monitors allow the operations group to analyze and identify changes needed that will keep the process running within specifications hours in advance. The old mantra in plants was that you only cared about how the process ran for your shift, but that’s all changed. With automation and big data trending, plants are leveling out and running in a proactive mode.
This data also lets plants and operators look back at times the plant experience issues, determine the cause and how to better approach it the next time those same circumstances arise again. Learning from these issues will make processors more efficient, and potentially more profitable, in the future.
FE: What key takeaways should processors have after this Q&A?
MB: The journey to automate single machines, multiple machines, entire production lines or even the entire plant should not be feared. There are many challenges in the process of making these changes: don’t be hesitant to bring in groups that specialize in this type of project. Often companies have that normal “we can figure it out” attitude that made the business successful, but this is not one of those times when that works. Manufacturers all too often underestimate the money, time and resources needed to perform these tasks. Do not follow that path. There are a multitude of technological advancements that can make a facility cost competitive, efficient and profitable if implemented properly. Let this world be opened to you but do not start the journey alone. Rely on the many very qualified resources in industry that can help make it a more seamless transition. Use those experts, knowledge and experiences to your advantage. FE