Recently Copper Glow Technologies has had the pleasure of working with a variety of customers across different sectors that have no modern forms of automation in their facilities, and it’s been quite the challenge. As a highly technical controls-based company the struggle has been to understand how a company operating in the “modern” manufacturing space could operate without knowing what a PLC is. After journeying down the automation rabbit hole, the fundamental questions such as “what is a PLC?” becomes incredibly difficult to answer. Exploring the idea of what a PLC is required a reframing of the way we looked at the question. To do this, we explored a childhood concept of determining the “who, what, when, why, and where” of PLCs. The question of “what is a PLC?” is incredibly broad so this article will explore some of the most basic ideas without diving too deeply into the rabbit hole.
1. What is a PLC?
In its simplest form, a PLC is an industrial rated computer capable of receiving inputs and producing outputs through a set of programmed instruction. A PLC differs from a “consumer grade” computer as it can operate without intervention 24 hours a day for years at a time. It can perform a wide range of tasks from simply turning lights in your facility on and off to controlling complex machinery. PLCs are simple to make changes to and can be programmed in a simplistic programming structure called ladder logic. PLCs can connect to any variety of sensors to take real world data, perform a logical action inside of the PLC, and create a real-world result. By utilizing modern communication media such as ethernet or Wi-Fi, PLCs can provide real world sensor data or calculated results to anywhere in your facility or even then world. This connected network of a PLC to sensors can be referred to as an automated system or simply automation.
2. When were PLCs first created?
The first production PLC was built in 1968 – 1969 by a company called Modicon. Before the invention of the PLC, machines and systems were run using relays. These banks of relays could be small for simple processes or have hundreds of relays for larger systems. The wiring and commissioning of these large relays systems was incredibly complex and prone to mistakes. Troubleshooting or making changes to these complex systems could be incredibly difficult.
3. Who uses PLCs?
About every industry utilizes PLCs in one form or another. Nearly every aspect of your life is made possible using PLCs. The breakfast you eat in the morning was probably produced in some sort of process that utilizes a PLC. The traffic lights you encounter on your drive to work are PLC driven. The heating and cooling systems at your office could be controlled by a PLC. The package that gets delivered to your front door from another part of the country travelled through a highly technical PLC controlled system to make it to your house. PLCs play a fundamental role in our everyday lives whether you know it or not.
4. Where can a PLC help my facility?
A PLC can be a Swiss army knife for your facility, which can be overwhelming when you begin the process of incorporating PLCs into different processes in your facility. There are four major gains that a PLC can offer to your facility: Safety, Maintenance, Efficiency, and Quality.
Safety Gains – A PLC allows for complex safety systems while keeping them maintenance friendly. By utilizing a PLC, safety systems can achieve PLe / SIL4 levels of safety without the extreme complexity that would be present in a hardwired solution.
For example, a standards safety door entry to a moving system with high kinetic energy requires multiple safety requirements to be met. One of those requirements is for the motion to be completely stopped before allowing the safety door to open. In a hardwired solution, safety rated timing relays and miscellaneous other hardware is required to provide the correct timing. With a PLC controlled safety system, the PLC can monitor the kinetic energy and once it reaches zero, allow the door to open. Because the safety system is being controlled by a PLC, changes can be made rapidly and with greater ease to allow your safety systems to be flexible while still maintaining their overall safety requirements.
Maintenance Gains – Information is one of maintenance’s most important tools. Using automated monitoring systems, all the information maintenance needs to keep your facility running becomes readily available. By utilizing relevant devices to the process, the system’s PLC can capture and trend data for review.
For example, a motor can provide data such as amp draw, winding temperatures, vibration, etc. By capturing that data, a PLC could be set with setpoints to prevent the motor from catastrophic failure. It could also be set to alert maintenance when a parameter is out of typical range and indicate that a problem is occurring.
Efficiency Gains – Whenever a facility is looking to increase efficiency in a process, the discussion always starts with how to eliminate a human interaction with the process. If a process can operate at 50 items per minute but has an operator station with an operator capable of operating at 30 items per minute, the operator is limiting the process. By applying a PLC to control a process that eliminates the operator station, the bottleneck could be reduced or eliminated which will increase the overall efficiency of the process.
For example, a filling process has five different product manipulations: filling, process adders, sealing, and capping. The process adders, in this example will be a package of desiccant, is an operator hand filling station. The filler, sealing, and capping can fill at 50 containers per minute while the operator hand filling station can fill at 20 containers per minute. By replacing the operator hand filling station with a PLC controlled addition machine capable of operating at 50 or more containers per minute, the line efficiency has been dramatically increased.
Quality Gains – By using an operator to conduct quality assurance functions, the quality of your product is only as good as your worst operator on their worst day. Automated systems are commonly used in facilities to conduct in-process quality inspection. For example, by applying a PLC controlled machine vision system, a process can be implemented to inspect every product that passes through it for a variety of manufacturing defects. By adding different PLC controlled inspections in-process, manufacturing defects can be rapidly identified and corrected that might have been missed by a manual inspection.
Additionally, by identifying defects in process, defective product can be removed from the system. In a process where the raw material is manipulated multiple times, the additional manipulations will not happen on a defective product. For example, in a process of filling a container there could be four different product manipulations that occur to each container: filling, capping, labeling, and coding. If a container fails to get filled and is removed from the system, the subsequent manipulations do not occur. This means that the container will not be capped, labelled, or coded.
5. Why is a PLC an investment in your facility’s future?
A PLC can operate 24/7/365 improving the safety, maintenance capabilities, efficiency, and quality of your facility by providing the core to your automated systems.
Business is constantly being influenced by factors such as supply chains and product demand. This can create hurdles that facilities with automated systems can navigate with relative ease when compared to their non-automated counterparts.
Imagine a manufacturing facility that has operated in the same way for the past 20 years. This facility has received their raw materials from the same manufacturer in the same form. This has allowed their sensors to be hardwired directly to devices such as air cylinders and product manipulators. The simple nature of the automation at the facility has been sufficient.
“Why fix what isn’t broken?”
Then a disruption in the supply chain causes their raw materials to change. What used to be a 50lb tote is now a 10lb case. The process must change, and that change takes the form of making physical changes to the process. In many cases this means that entire parts of the process need to be reworked and, in some cases, additional processes need to be created. To accommodate the changes in the process, non-automated facilities will bring on additional labor. In the short term, this strategy has worked in the past.
Manufacturing labor has been in dramatic decline for years leading to the available pool of manufacturing labor to be lower than the number of available jobs. On the opposite side, demand for manufactured goods has increased. For this imagined facility to maintain levels of production to match the rising demand with less labor, something must change, and that change is the addition of PLC controlled processes.
In contrast to the non-automated facility, the automated facility typically can make changes in their automated system to accommodate the process changes. Recipes can be created to allow the process to switch between the 50lb tote and the 10lb case with ease. Sensors can be reprogrammed inside of the PLC to change their operation in relation to the same cylinders and product manipulators. These facilities can respond quicker to process changes which in turn allows them to continue to operate with the same available labor as before.
What is a PLC?
- It is a force multiplying tool for your facility.
- It is the core of an automated system.
- It is how your facility increases its safety, maintenance capabilities, efficiency, and quality.
- It is how you ensure your facility is ready for whatever comes next.