In the first part of How to Adopt OEE More Effectively, we reviewed OEE calculation (Overall Equipment Effectiveness) and how it can be used to improve a plant's performance. This week we are going to talk about how to use it properly.
Equations from Part I:
OEE% = Availability rate * Performance rate * Quality rate
This leads to three more equations for each rate:
- Availability Rate = Available Time (total working time - start up and shutdown time) / Scheduled Working Time
- Performance Rate = Actual Output (running speed) / Standard Expected Output (maximum effective speed)
- Quality Rate = Customer Usable Produce / Total Output Product
Based on the equations from last week, we have six main areas that can improve your OEE.
- Availability Time can be improved through:
- Reducing the frequency of breakdowns
- Reducing startup and shutdown times
- Performance has the opportunity to improve upon:
- Reducing break times and idle times not due to breakdowns (employee break times and scheduled maintenance)
- Possibly increasing speed as long as quality is not being reduced (Finding the optimal speed and running at it)
- Quality has the possibility to improve by:
- Reducing the amount of rejected final products
- Optimizing when the machine starts production
- This means looking to see if there are more rejects during startup time
- If so, it may be better to not try to produce during startup if possible
The improvements to availability stem from both the machine and employees. You can reduce the frequency of breakdowns through upgrading an old machine, making sure your employees have proper training, and performing preventative maintenance.
All of these can help prevent breakdowns during production and often tend to require less time than fixing the breakdown on the fly once it occurs. Reducing startup and shutdown times may not be an option to you, but it is worth looking into because it does take away time from production.
The improvements to performance and quality go hand in hand although they are evaluating different things. Performance can first be improved by reducing idle times. These are scheduled breaks including: employee breaks and maintenance breaks for the machine.
You can reduce idle time from employee breaks by offsetting breaks to make sure an employee can keep the machine running all day. Maintenance breaks are a loss you may have to endure no matter what, but looking into reducing this time even minimally can help your OEE improve greatly.
Quality affects the second way to improve performance. This is optimizing the speed that the machine is run at, as well as whether or not to produce during start up time. Optimizing means looking to see if your machine has less rejects at 80% vs. 100%. You may need to take a loss in either quality or performance, but there is no need to take a loss in both.
Ultimately, quality boils down to how many of your output products can go to the customer. Is it worth spending the time fixing rejects or worse wasting them by throwing them out? It may be if you have a minimal loss, but it may not be if you have a low quality. To improve this you have to look back at performance and see if it is better to run at a slower speed.
Achieving World Class OEE
The goal when looking at these issues is to improve, not to be perfect.
No production line will truly get a 100% efficiency rating; however, each improvement will save you money as well as help you to improve your revenue. OEE is a measurement tool. If a company sets low goals, they can achieve a score of 100% or even higher. This does not mean that they are perfect. They may need to revisit their goals to see improvement. Even if they don’t, looking at these areas for improvement will still help them to improve their score.
Looking at your OEE data may give you a shocking value upon your first review. Whether it is low or high, this value is only a benchmark. A 17% is not necessarily a worse score compared to a company that receives a 93%. The scale for evaluation may be completely different. The true use of OEE is for overall improvement. Taking a look at the six possible issues mentioned above can help to raise your OEE. As long as there are improvements you are using this tool correctly and helping to improve your company. Ultimately, you are putting more money in your pockets.
If you're still not sure where to start, considering partnering with an automation solutions company like Premier Automation. With a team of over 20 in-house engineers, we have experience in production data collection across a broad range of industries – we can help you identify useful OEE metrics and put in place a system for both collection and analysis. Contact us for a free consultation to get started: