Hello everybody, it’s been far too long since my last blog, maybe this was because of having a very busy 2016? I think that’s probably the reason! Thank you to all my customers and partner organisations for another successful and challenging year.
So, it gives me great pleasure to be able to sign off 2016 – a strange and troubling year in many ways – with some positive learnings that I want to share with you all about Flow.
I’ve been working with a couple of clients this year who have production lines containing several fairly complex processes which are very closely coupled to each other. In other words, there is little conveyance or buffer between each step. Somebody, at some time, probably decided that these lines should be ‘super lean’, and that as waiting & inventory are muda (or waste) in the eyes or a lean practitioner (right?), buffer has been almost completely eliminated. Shouldn’t be a problem if the line runs as it was designed to do, you might think.
The reality of course is very different! In practice these lines run badly. Any minor stoppage (and there are many) can quickly stop the whole line. So, the people working on these lines spend most of their time at work running around trying their best to keep production moving in some form or another. It’s a frustrating and stressful environment for people to work in, and despite their best efforts the OEE numbers for these lines is flat-lining.
What is happening with these lines? Is it due to ‘over-zealous’ implementation of lean principles at the line design stage? Or could it be that there is a lack of understanding of line dynamics, and how best to balance the flow across multiple assets? Perhaps there’s an assumption that each asset will run at such a high level of availability, and without problems, that flow will never be impacted?
A ‘perfect’ production line would probably have the following characteristics:
– Capacity would be perfectly balanced
– 100% Asset availability (no breakdowns, no minor stoppages etc)
– All products would run at the same speed across all processes (or the line would be capable of flexing to new speeds across all assets equally)
– Changeovers would never be required, or if they were would be done instantly, with no time loss
– Inputted parts and materials would be made to tight tolerances with no discernible variations affecting machine performance
– If manned, then skills and knowledge of how to run the process would be at a high level across all shift teams
If all the above was in place, then there’s no reason why your ‘super lean’ line shouldn’t run extremely well. But, in the real-world things just aren’t like that! Breakdowns and stoppages occur (often frequently, where there’s no well-established process of problem-solving). Products and parts vary, even if they are ‘in spec’. Machines wear out, and settings are often adjusted to compensate, maintenance is often completely ‘reactive’. People’s skills, knowledge and motivation can vary enormously across teams. It only needs some of these factors to be in place for a multi-stage production line to start to under-perform.
So, what needs to be done to get control of the situation and ensure that these problematic lines start to generate better levels of performance? The answer lies in being able to ‘Balance the Flow’.
We need to accept that in the short-term, attempting to balance capacity across multiple processes is a ‘fool’s errand’. There will always be issues and problems which mean that you won’t get what you think you’ll get, in terms of output and line performance. ‘Balancing the Flow’ means accepting that there will be a ‘bottleneck’ process, and our line design should be configured in the form of a V-shaped curve (which often more resembles a tick). It also needs to build in some ‘buffers’ in terms of Time, Inventory & Capacity, especially around the ‘bottleneck’ process itself. This might be heresy to some lean practitioners, but ensuring that the ‘bottleneck’ is never starved of product by issues upstream, and never stopped because its outfeed is blocked due to issues downstream, is a vital part of ensuring the line as a whole performs well. Get this right, and see what an amazing impact it has on performance of the total line.
The 3 Basic Rules for better ‘Balancing the Flow’
• Maintain the Bottleneck in a running state, ideally at its optimum speed. Do whatever it takes to ‘protect’ this asset
• If the upstream or downstream equipment fails, maintain the Bottleneck process in a running state for as long as possible (this is where you might consider having some supporting inventory as a ‘buffer’)
• If the Bottleneck stops, try and restart it as quickly as possible
There’s a lot more to ‘Balancing the Flow’ and line dynamics, but the above gives a good start. If you want to know more about this subject, I’ve posted a couple of links to the bottom of this blog. One is to ‘The Goal’, Goldratt’s seminal work on optimising your bottleneck, and the other a Slideshare link to some slides from Optimum FX Consulting, that explain the principles I’ve described above in a very elegant way.
If you want to know more about how to ‘Balance the Flow’ in your lines, and how inter-dependencies between your assets cause big losses to the whole system, please get in touch. I have a great training tool that shows the impact of this, that I can take you and your teams through, as a starter to improving your line performance through better Flow.
It just remains for me to wish everyone a Merry Christmas & a Happy New Year! Let’s hope for an outbreak of ‘Peace on Earth and Goodwill to All Men’.