OEE (Overall Equipment Efficiency) and Downtime

[phil1234]

I would like to know how to account for a machine that is broken and unable to produce for an extended period of time.
We have 5 machines and one is going to take a week or more to repair: does this mean that my "Availability" is straight away reduced by 20%, or do I ignore it completely?
I want to ignore the machine and take it out of the system - my bosses say there are financial considerations (depreciation etc.) to take into account. Further, if the machine is not recording a downtime, how do we justify (show) decreased production further up the management ladder?

 

[harry]

Re: OEE (Overall Equipment Effectiveness) and Downtime

Welcome Phil,

After you had titled your thread and posted, the forum software will automatically searched and come up with some similar discussions/topic found in the 'similar discussions' box - just scroll down the page. The first thread: OEE (Overall Equipment Effectiveness) Downtimes Calculation may be relevant for you.

Next, you can do a search. I use 'tag' search and found 'oee' - with a number of recent threads (note: we started tagging only recently and what you get from this search are limited to some recent threads - with 7 threads, should be good enough). One good thread is: Overall equipment effectiveness - Computing OEE taking all machines taken together

 

[phil1234]

Re: OEE (Overall Equipment Effectiveness) and Downtime

Hi Harry
I looked at the other posts but they were mostly old (one going back to 2005!)
I think most people would scan latest posts first (last 24 hours)and take it from there............
I appreciate your advice, thanks.

 

[wmarhel]

Re: OEE (Overall Equipment Effectiveness) and Downtime

I would like to know how to account for a machine that is broken and unable to produce for an extended period of time.
We have 5 machines and one is going to take a week or more to repair: does this mean that my "Availability" is straight away reduced by 20%, or do I ignore it completely?

Two factors to contend with. First, when the machine broke down and "halted" production then that would be a factor that affects your OEE. Once it is decided that the machine needs to be removed due to extensive issues such as total failure or a safety risk; then it could be considered as scheduled maintenance. The reality though is that you shouldn't be trying to game OEE because a number drops signficantly. The real purpose of OEE is to benchmark a current state, highlight the issues that reoccur, and monitor the effectiveness of the programs you put in place.

I want to ignore the machine and take it out of the system - my bosses say there are financial considerations (depreciation etc.) to take into account. Further, if the machine is not recording a downtime, how do we justify (show) decreased production further up the management ladder?

First off, the machine depreciates whether it runs or not so that shouldn't be a factor. What would be more likely is that the machines doesn't run, so your controller it can't absorb overhead. Still silly, but hey; creating bad habits for operations is what accounting does best. The only financial consideration is that you may not be able to meet customer demand; or that the repairs may more costly than the justifiable.

There are anumber of posts here on OEE and aspects related to it, I would recommend you a do search here on The Cove as already mentioned.

Wayne

 

[phil1234]

Re: OEE (Overall Equipment Effectiveness) and Downtime

Hi wayne
Thanks for your prompt reply:
What you suggest is what I did: The machine incurred downtime for 2 days or so until it was established that the breakdown was severe; at that stage I put out an email stating that the machine was "officially out of service" until further notice and removed it from my calculations. Management are questioning why my figures aren't reflecting a huge increase in downtime (which I am now showing as 12%, across the other 4 machines). They have to justify spending $25000 to repair this machine and WANT the downtime to reflect this.
I feel that I am correct in my calculations, but find it difficult to answer their argument.
Previous posts about downtime have only mentioned short periods, not an extended period such as mine.

 

[harry]

Re: OEE (Overall Equipment Effectiveness) and Downtime

Hi Harry
I looked at the other posts but they were mostly old (one going back to 2005!)
I think most people would scan latest posts first (last 24 hours)and take it from there............
I appreciate your advice, thanks.

Actually you should be looking for discussions that are relevant to your situation instead of whether a thread is new or old.

Not sure about you but I did come across a post where Wayne was essentially talking about the same thing ie: A machine which is down but not scheduled for production (or taken out from the schedule) cannot be included in your calculations.

On the other hand, if you are taliking to accountants, why use OEE? How many of them really understand? Why not talk about opportunity cost?

 

[Ajit Basrur]

Re: OEE (Overall Equipment Effectiveness) and Downtime

I would like to know how to account for a machine that is broken and unable to produce for an extended period of time.
We have 5 machines and one is going to take a week or more to repair: does this mean that my "Availability" is straight away reduced by 20%, or do I ignore it completely?
I want to ignore the machine and take it out of the system - my bosses say there are financial considerations (depreciation etc.) to take into account. Further, if the machine is not recording a downtime, how do we justify (show) decreased production further up the management ladder?

Overall Equipment Efficiency (OEE) is a formula that shows the overall performance of a single piece of equipment, or even an entire factory, and is governed by the cumulative effect of three factors: the equipment’s availability (percentage of scheduled production time available), performance rate (percentage of parts produced compared to standard), and quality (percentage of saleable parts produced compared to parts started).

Putting in equation, it would be = Availability (%) x Quality (%) x Performance Rate (%) - for more info, you could have a look at Overall Equipment Effectiveness - Common Interest Workgroup

One of the major shortcoming of OEE is that it doesnot relate labor with equipment and should not be used as a stand alone metric. Also, OEE does not have a comparable cost metric and doesnot take figures such as depreciation and scheduled maintenance.

If you want to consider the financial aspects, consider some other metric.

 

[phil1234]

Thanks Harry and Ajit
It's 11pm Sunday night in Perth, I'm off to bed but will be back soon!
zzzzzzzzzzzzzzzzzzzzzzzzz
Ajit, I know how to calculate run of the mill events regarding OEE, my problem, as stated in the beginning, is how to handle a major machine breakdown, an exceptional event for me - this is the longest outage that I have had to account for, hence my "panic"

 

[adrianpask - 2011]

If i may throw my thoughts in as well:

What is the intention behind collecting OEE data?

- For me it's to identify the losses to the manufacturing facility - the reasons why you're not producing.

Therefore i would like to offer 3 thoughts:
1. If the machine is down one argument may be that it's limiting the total output of your facility and in the short term whilst it skews your numbers, a reduced OEE is an accurate representation of why your output is reduced. When you look back in 12-24 months time the reduced output is accurate.

2. What is the reason for the machine breaking. If the cause is related to a lack of maintenance/lack of lubrication. Then in my opinion these are losses that should hurt your team as they are responsible. If the reason it's broken is down to what one of customers calls "an act of god" then they believe it's right to remove from the numbers.

3. People like numbers that they can hit. What's your intention for measuring OEE - if it's to motivate people and they can't effect the output then that can be a tricky message. One of my sites needs to invest capital to repair a machine part that causes slow running. They say their oee should be weighted whilst they're waiting for approval and in the meantime why should they be penalised for the poor performance? Again - this is a choice and i encourage them to think long term - in 24 months time they are doing no favours by hiding the loss.

With any number my belief is that it should be honest, consistent, transparent, and representative. As soon as you start weighting or changing due to environmental reasons you've lost it!

 

[adrianpask - 2011]

Woop - i can post links!

Check out this article - it's got some suggestions on a whole range of measures for you so i hope it adds value:

http://www.worksmanagement.co.uk/articles/17995/So_you_think_youre_good_enough.pdf