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Small causes with large effect: the 80/20 rule of OEE Consulting

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Any loss in production is expensive for manufacturers. To achieve maximum effectiveness of your machine, it is essential to know the exact causes of performance losses. We can identify them by using OEE as a key performance indicator. OEE stands for Overall Equipment Effectiveness and states the ratio of the actual to the theoretical output. The calculation of OEE considers three of the most common reasons for productivity losses: availability, performance and quality. These factors are expressed in percentages as comparative values, which are the basis for our OEE Consulting.

 

Availability refers to machinery and workers that enable production according to a schedule. Its score is calculated by comparing planned with actual machine production times. To determine the Performance of the equipment, the actual machine run time is compared with the run time that is theoretically necessary to achieve the produced quantity. This shows if your machine is running at optimal speed. The factor Quality is used to specify how many products do not meet the required quality standards and are therefore rejected.

 

The three performance figures are collected either with an internal or external measuring system over a period of about four weeks. To visualize the measurements, they are documented in a chart, allowing us to clearly see which of the indicators has a negative impact on overall equipment effectiveness. In our example (graph 1) there is a clear analogy between the availability rate and the OEE curve, highlighting that it has the biggest impact.

 

Graph 1 Time series plot: influence of performance figures on overall equipment effectiveness

 

Within the scope of our OEE Consulting service we find out reasons for the low availability. The Pareto Chart gives us the starting point (figure 2). It shows the number of machine downtime notifications that result in availability losses.

 

Graph 2 Pareto Chart: downtime notifications, which resolve in availability losses

 

In this case, 78 percent of unplanned machine downtime is caused by a missing product and the stopping of the conveyor belt. The aim of OEE Consulting is to find out what the main reasons for these signals are and to minimize them through tailored action in order to improve your overall equipment effectiveness. According to graph 3, a raise of availability by 30 percent would mean, that we could achieve an increase of the overall plant effectiveness from 44.4 percent to 57.7 percent.

 

Graph 3 OEE control chart: enhanced OEE after availability increase of 30 percent


Contact:
Roland Pichler
Manager OEE Consulting
phone: +41 (0) 58 674 6357
email: roland.pichler@bosch.com

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