The calculation of Overall Equipment Effectiveness (OEE) considers the three main factors that influence productivity losses: availability, performance and quality. Before the reasons for this loss in machine productivity are known, a sustainable OEE improvement cannot be achieved.
In our last newsletter issue pack insights, we showed how, for instance, the factor “availability” can have a negative impact on machine productivity. The Pareto Chart provided a first indication of possible causes. It shows the frequency of the machine downtime notifications which are responsible for the availability loss. In our example, the main reasons were attributed to the effects “no product” and “stop of conveyor belt”. Our goal is to reveal the root causes of those effects within our OEE Consulting program.
How fishbones help to visualize causes
In a first step, we form a project team consisting of your machinery and product experts, as well as an OEE consultant and machinery specialists from Bosch. Together we methodically identify the profound causes for all the detected effects. First of all, the project team collects possible reasons for the encountered effects in a brainstorming session, then bundles them into cause clusters such as “product” or “speed”. Subsequently, the actual interference factors, such as “wrong product size”, will be identified.
The causes of each effect are pictured in a fishbone diagram. This way of visualising the cause-and-effect relation is also known as Ishikawa method. Here, the head of the “fish” correlates with the respective effect, whereas the fishbones correspond to the potential reasons. This method facilitates the expert team’s next step: evaluating the causes in an impact analysis. Find out more about this topic in our upcoming newsletter!
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