When It Can Be a Good Idea to Use Several OEE Key Figures with Diverging Target Times
By Matthias Kohlbrand In Alongside the sum of recorded downtimes, the target value for a cycle time has the greatest influence on the value of an OEE (Overall Equipment Effectiveness).Among others, in Cosmino MES Plus, this target value can be correspondingly defined differently depending on the tool, the operation, the product, the machine used and the level of the operator count.
The target time for a cycle, however, is not only used for the determination of the key figures, but also for the calculation of offers and the planning of orders. It could therefore be assumed that the quality of the default value is completely valid and up-to-date and that therefore, there is no need to adapt it or even apply it to different versions..
The reality is often different, however. Maybe you are also among the majority of those who correct the cycle times upwards or downwards due to new knowledge, through cycle measurements via a Cosmino machine data recording, for example. If the default values are longer than the actual cycle, many users could also accept them and avoid completing a correction of the default times. It should be possible for an adjustment to be made nevertheless, however, as with incorrect cycle defaults, the calculation will also be wrong.
It becomes interesting when the performance of departments or entire plants is compared using the OEE key figure. Comparisons of this kind are generally questionable, however, unless processes are absolutely identical, and the production takes place in series only. This is because the OEE “punishes” small lot sizes and therefore frequent setup work. From the OEE perspective, this is therefore a problem if that is exactly what your customers want.
As described above, both the machine, which is used, the tool and even the personnel can influence the cycle time. It is idealistic to assume that all of these factors are always identical across all of the areas for comparison and are therefore comparable.
The problem: The more valid your target times for a cycle are, the more valid your OEE – but the value will not be in the place where you or others would like to see it. And whenever you have to correct the target times downwards – because the processing time of a part is shorter than expected after all, or because you have brought about improvement measures – the OEE value deteriorates.
Therefore, the last major release in May 2021 now includes the interesting feature that different cycle data defaults can be evaluated per combination of machine-product and, if necessary, also tool or operator count.
In the Cosmino cycle Master Data, the types are as follows:
- Current: The tried-and-tested cycle default for your OEE calculation
- Group definition: Possible deviating default of the group with which the comparison is to be made.
- Baseline: The original default time before the cycle data were adjusted in the first place. Only according to this can you see the actual improvement since the introduction of the OEE recording.
It is now possible to create default times for each of these types as Master Data with Cosmino. To provide appropriate OEE reports for the different cycle types, we will be very happy to analyze your requirements and then implement the evaluations for you. We look forward to hearing from you.
Regardless of the cycle you use to calculate your OEE: The most important thing about the OEE key figure is not the value, but the knowledge of the causes of the delta of this value and the 100%. Cosmino MES Plus also supports you with this task.
Abb.: Illustration: Example for Master Data from cycle data