By Tom Hechtman
By Tom Hechtman
Improving the efficiency of manufacturing facilities is on every manufacturer’s mind, especially in today’s economy. The difficult part is knowing how to improve efficiencies, and determining the areas to concentrate on and the best time to implement such improvements.
That is where overall equipment effectiveness (OEE) comes in. OEE is about learning where and how to improve operations, so that a company can increase profits and gain a competitive edge in the market. OEE is a hierarchy of metrics used to monitor the effectiveness of manufacturing sites. Software is typically used to simplify the ongoing process of collecting and analysing the results, but it takes much more than using OEE and OEE software to improve efficiencies. Both technical and human factors play a role in making an OEE implementation successful.
Technical OEE factors
Think about the technology generally available today. We can go up to any ATM in the world and withdraw cash, provided that the cash is in the account. We can watch streaming video programs on our televisions in high definition. With our mobile devices, we can do nearly everything we do on our computers.
The technology is available today to implement an OEE system that doesn’t require paper and spreadsheets. Even with this technology, however, companies are still stubbing their toes on the technical aspects of OEE. Below are just a few technical points to help prevent a sore toe:
• Use the OEE calculations. Don’t reinvent the wheel. Use the standard OEE calculations already available. OEE was developed to measure plant performance across manufacturing facilities of varied sizes and types. It includes three isolated factors – availability, performance and quality. Each can stand on its own, but combined they provide an accurate picture of a production line’s effectiveness. OEE availability represents the uptime, excluding scheduled downtime periods such as breaks. OEE performance is represented by the production rate while the production line is running compared to the ideal production rate. OEE quality represents the good units produced compared to the total units that started being produced on the production line.
• Track downtime. OEE is used to track the effectiveness of production lines, but it is just a metric. It doesn’t tell how to make a production line more effective. More information is needed, and tracking downtime will help to identify what areas to focus on to improve effectiveness.
• Include scheduling. Every facility has some form of scheduling, but often the excuse is given that a scheduling system cannot be used because schedules are too complicated. The complication usually is a result of frequent and, sometimes, last-minute schedule changes. The scheduling system must be flexible and easy enough to use so that it is not a hindrance for scheduling staff. Low efficiencies result from ineffective procedures or a lack of communication between departments. This is where scheduling helps by providing current schedule information and change notification to all associated departments.
• Test. Inaccurate data leads to a loss of confidence and a lack of commitment of the staff. This is why it is important to fully test an OEE system before going live. It also makes a good argument to use a proven OEE and downtime software solution instead of diving into a custom program. Garbage in equals garbage out, no matter how you present it. Testing should start with the data being entered into the OEE system. This usually starts with the PLCs or other plant floor controllers, but also may include data from other software systems, such as an enterprise resource planning (ERP) system.
• Use standard technologies. IT departments are familiar with standard computer technologies. They are familiar with, and probably have training on, industry standard SQL servers. They know how to maintain them and keep them running smoothly. Using proprietary or locked down databases will create data islands, which will prevent the sharing of data between software systems. In many facilities, the IT department is also responsible for keeping the office and plant floor computers running without problems. By using standard technologies, their job will be simplified and they will be more willing to support the OEE effort.
Human OEE factors
Everyone is responsible for reliability and productivity. It is a team effort, but it starts with leadership. If left to individuals to do their part, projects will fail because sometimes employees are just not willing or are resistant to change. Leadership will have to set the stage and motivate the whole team to do whatever they can to contribute.
Below are just some of the steps on the human side to help make your OEE implementation a success:
• Education and training. A source of resistance by some individuals is the unknown. They wonder: “Are they tracking me?” “Will I use the system incorrectly?” “Will it make my job harder?” Educating employees on why OEE is important for the company, how to use the system and how the results are going to be used will ease the resistance. Designate a trainer to teach all users involved. Otherwise, each person will handle the same situation differently, which will create inconsistencies in the OEE results. If everyone handles the situation in the same manner, the OEE results will be consistent. The trainer should also make up standard procedures that are available online or in printed form.
• Include production staff in the design. An OEE system should be more than a management tool. The best phrase that comes to mind that represents this concept perfectly is, “getting the right data to the right person at the right time.” Just getting real-time data to the production line operators will make an improvement in efficiencies. Operators don’t like to see their numbers dropping. Ask efficiency-related questions, listen to the challenges of the different departments, and look for ways the OEE system can help minimize their challenges.
• Keep it simple. It is fairly common to find production management and their support staff feeling overwhelmed with keeping up with daily production issues. Adding OEE to their plate can increase this feeling of overload, even though it will make their jobs easier in the long run. Don’t overburden staff with too much data to analyse. Only provide the data that employees can take action on. Initially, it is best to keep it simple – have a smaller set of downtime reasons and determine which work cells are the top sources of downtime. Then, if needed, add more downtime reasons to only those work cells to zero in on the inefficiencies.
• Close the loop – It’s a circular process. Once you obtain your OEE values, the next step is obvious, but is often neglected. Take action! First, determine the low hanging fruit. These are sources of inefficiencies that will be easier to resolve and will yield the greatest improvements in OEE. Next, analyse the data, identify the top causes of inefficiencies and, if practical, resolve them. If it is not practical because of cost or other technical issues, move on to the next item on the list. If it is not clear what the source of an inefficiency is, collect more data. This may include adding more downtime reasons, analysing the quality of data or even placing a person at the problem area just to make observations.
Implementing OEE is not the answer to end all inefficiencies, but it will help. Just think about what could happen if your operating efficiency improved by just one percent.
Tom Hechtman has been implementing manufacturing execution system (MES) projects for more than 20 years. He is the MES channel sales engineer at Inductive Automation. He has been instrumentally involved in the OEE Downtime Module, which is part of Ignition by Inductive Automation’s MES software suite.