Q: What is Overall Batch Effectiveness?
Dennis McCarthy • The logic of batch OEE is to measure the flow of material through the end to end process stages rather than each asset individually. Collate the data by asset and you can identify the losses at each asset. You don’t need it where you have continuous flow but where there are assets that are not used all the time, you can quantify what impact that asset had on the value stream. I hope that this helps
Arno Koch • Ok, so I understand you ‘sit’ on the batch and see what is happening to it, right? Might be called “overall Batch effectiveness” or even better “Overall Valuestream Effectiveness”.
I see the charm in this approach; it gives a ‘number’ to the performance of a value stream (however it is quite far from the concept of OEE).
Now how do you determine the theoretical maximum speed for the batch, considering it moves over equipment with different maximum speeds?
And how do I see in this approach how a 60 Mio € machine has to wait all the time because it is in a non-balanced line?
Dennis McCarthy • Effectiveness is a measure of how well you did what you planned to do. So overall batch effectiveness (great idea) is about how well the batch went through the system as designed. We apply this OBE approach to systems such as logistics or stores operation by considering Availability losses as things which stop you from doing what you plan to do. Performance as things that take longer than expected and quality losses as non optimum output quality. If you look at OEE the six hidden losses can be categorised as 1. planned or inbuilt losses such as (set up, reduced speed and start up losses) and unplanned losses (breakdowns, idling and minor stops and rework). These are 6 different types of problems with 5 different focussed improvement tactics. These tactics can be applied to any system. The question of line balance is not something that OEE is designed to measure but because OBE records time the batch spends waiting for processing it also highlights the out of balance condition because there is no waiting time at assets with capacity and lots of waiting time at bottleneck assets. The approach works fine. Its not right for every cirumstance but I hope that you can see how Batch OEE or OBE doesn’t create blind spots, it was designed to shine a light on losses that would otherwise remain hidden. Again I hope that this helps
Dennis McCarthy • Sorry one more thing. In terms of maximum throughput calculate the maximum output at each stage of the process then you can see how the batch performed against it. An alternative is to treat the system as a black box which as with any line OEE will be determined by the pacemaker unit.
Arno Koch • Dennis, it’s an interesting discussion that shows how different perspectives give different views! I fully agree that your ‘OBE’ approach is absolutely a valuable measure to identify losses in a value stream. I would encourage measuring this in ANY process, since it might reveal many obstacles that are taken granted for.
OEE however, as you also mentioned, has a different focus. It looks at one point, at one machine in the value stream. While looking there you usually get tons of hints about problems in the value stream or in the organization around the machine (assuming you defined the parameters smart), but still it looks at one fixed point. This has its advantages and disadvantages.
If we look at OEE in its purest form, it defines 100% OEE as what the machine could do at its THEORETICAL maximum. Of course there is a grey zone that might be discussed. However if the goal is to reveal ALL POTENTIAL losses, it has to be taken literally. So OEE does not measure against what you planned to do but against what you could have done in the theoretical/hypothetical maximum (even if at this point you see no way how to get there; that is the challenge for many SGA’s); this is a fundamental distinction from OEE and most other measures!
At this point one might call me an extremist… If I measure OEE of a machine in a chain of machines, most people take the maximum speed of the slowest machine as the maximum of the whole chain; thus “hiding” the capacity of all other -faster- machines. I would do the opposite: I take the maximum speed of the fastest machine in the chain as the maximum of the line. Now everybody is being challenged to find out what could be done to get there, knowing that maybe we will never achieve it… Hey, what the heck; it was and is never the goal to reach 100% OEE (and even 85% OEE might be complete nonsense in many situations, despite the persistent idea this would be World Class…)
Yet I know out there due to this approach now there are many lines that run faster than the original slowest machine ever did at its maximum! This is a phenomenon seen in every factory: look at the elder machines: even without TPM/LEAN or whatever; many of them already run far over the original design speed. Point is: Maximum speed is not written in stone, but you need to challenge it to stretch it!
So hip hip hurray for the new measure: OBE