When I first learnt the basics of lean thinking and lean practice, one of the base building blocks to help build better quality and faster flow in processes was the lean cell. And, the way I was taught was, to build your new future state value stream you put together new cells as each value-added section and then link them together with storage areas (supermarkets) and pull systems (eg kanban) and where needed. I like to think of it rather like a cell in your body, it is an essential part, but you need lots of them for your full body system to work effectively, and sometimes they can go a bit dodgy.
Lots of people keep asking me what a lean cell is, and why they are important and relevant, and why the word ‘cell’?
This is my understanding. As production grew and the knowledge of how production functioned during the early part of the twentieth century, a concept known as ‘Group Technology’ started to emerge (according to my very old notes this was in 1925). This is a manufacturing technique where instead of many different parts being moved from one machine process function to another, e.g. welding to soldering to pressing to cutting, instead the machines were grouped by the technology needed to make a family of parts. Grouping the technology to make the part family together. This meant that part families now could be made in a localised area, with a smaller number of machines without travelling far and wide around a manufactory, going through each process one by one, even just to be passed over. Group technology was based on the idea that by grouping similar parts together, into a ‘part family’, similar manufacturing problems would also be grouped together helping to make them visible and thus solvable. The main advantage of such an approach being the reduced transportation waste, as parts no longer need to traverse huge areas of a factory, improving on the previously quite innovative moving production line or conveyor system. Other benefits including the flexibility to change processes quickly grew and the ability to make smaller batches was a result of this flexibility in design.
The group of machines (technology) needed to make a part family became known as a ‘machine cell’, and ‘cellular manufacturing’ – the basis of ‘lean cells’. The goal of the implementation of lean cells being to improve flow whilst making as little waste as possible by connecting multiple cells together across a value steam. Each ‘cell’ therefore needs a clear product family purpose and logic for grouping a number of processes together within it. This idea was taken further by Ohno and Shingo in Toyota, whilst developing the Toyota Production System and Just in Time manufacturing processes.
Typically, a lean cell is ‘u’ shaped (there are other shapes like S too). I believe this to be because the flow in a cell is anti-clockwise, making it easier for a right handed person to work in the cell. There are 5 important elements of a lean cell. The foundational element is that of standard work. This details the description of the specific processes that take place in the cell, who does them, and how and how long each task should take, and how that rate of completion compares with demand or the ‘takt’ time for the process. The other four elements are: 5S, Visual Management, Flow and Pull.
5S and visual management help to make it clear when the cell is not fit for purpose, and therefore may not meet its goals due to problems. These two elements make problems visible, such as using shadow boards, so if equipment is missing it can be seen at a glance or if tasks are taking longer than expected, the visual management can trigger a call for help. This then help to ensure that waste is minimised as much as currently possible to ensure flow, ideally as close to one by one as possible (one piece flow), and pull triggers such as kanban cards, empty containers, or even lights can be used to visually call for the next part to move into production at the rate of demand, and when that area is ready. All these elements are designed to ensure that problems and defects in the process will show as soon as possible so that they can be amended before causing defects and harm. Thus improving reliability whilst reducing the wastes of inventory, poor communication, overproduction, defects, and waiting. The focus on swift, even, one by one flow without obstruction also leads to reduced overall flow time (end to end cycle time).
So, why am I telling you all this? Well this all came from manufacturing, I’m a manufacturing engineer, I find it fascinating. But how would/can we apply the theory, learning and concepts from this to health and care and should we? I have been able to apply these ideas with some amazing teams in health and care, (who did most of the work and thinking, not me btw) quite successfully in health and care settings (see here, here and here for example). And we got some pretty amazing results, reduced length of stay, reduced mortality, reduced defects, reduced costs, happier staff and happier patients and service users. So there is some value. But it does need adapting for health and care. Quite a bit. Not least because some basic principles of dignity and privacy of patients and infection control practices mean u-shaped cells are perhaps not so practical.
My learning so far can be summed up into 9 (non-exhaustive) areas:
1. Remember we are not redesigning a manufacturing process for parts. Real people are involved. (I’m sure this is obvious but it doesn’t hurt to restate this).
2. Pull systems work on the basis of ‘yes’ we have the capacity to accept the next one. Not arm twisting to accept another patient or add to a case-load; that is still push. Even if we use the word ‘pull’.
3. It is quite counter intuitive in health and care to implement visual management and 5S – hiding problems seems to be more culturally normal than seeking to reveal them. In addition the temptation to use these approaches for accountability purposes and blame rather than improvement can be higher than anticipated with some teams. Think carefully about the human and relational aspects of the changes incurred when trying to implement a ‘cell’.
4. Cells arguably need multi-skilled staff for them to work ‘well’, this I have found much harder in health and care where there are many professions to make important decisions together and often rota gaps. It might be more helpful to think about one (clinical) decision flow, rather than one piece flow, to help here.
5. If the main goal is to increase utilisation of something (say diagnostic capacity), then cells may not be a great solution approach, as they can increase downtime and ‘waste’ capacity (ie they need slack) despite improving flow (is the goal really utilisation tho’, or flow?)
6. How can you right-size a cell in a ward? How do you ‘group’ the technology into the families, and in what size of group’? What about in a reception cell, grouping the admin tasks together? What about a bay in a ward? How do you do it in a human resources department? In a payroll office? In a screening programme? In a district nursing team or a long term therapy unit? In a commissioning function? Trying to work this out is not always straight forward in health and care imho.
7. It is ok to use just elements of a cell as improvement tools, say such as 5S (or 6S if you prefer), that’s fine. In many ways, this how some of these elements were introduced in both western manufacturing, health and care. It’s kind of why lean practitioners got their ‘tool head’ derogatory nickname. The ‘well organised workplace’ module of ‘Productive Ward’ (for those of you who can remember that), for example is 5S repackaged; similarly, the ‘knowing how we are doing’ module is visual management. However, the strength, ‘magic’ and real benefit of each cell element only really ‘arrives’ when all 5 elements of a cell, are in in place together, and with leadership standard work to hold them there and further develop them. Rather like the pieces of a jigsaw, each has a picture on their own, but only together can you see benefit of the whole scene, and imho realise that these five elements of a cell are not really improvement tools at all, but leadership artefacts to help you to keep improving.
8. If cells are the answer, what was the question? Cells are designed to solve problems of waste for product/part/service families, if the goal doesn’t have an obstacle that cells might help you to remove or get around, perhaps they aren’t the answer. Other solution approaches are ok, cells are not a blanket ‘one size fits all’ answer.
9. The manufacturing technical language (jargon) of ‘cells’ is a bit off-putting. Yet, what else can we use care and health, and how can people find out more about cells if we don’t use the terminology?
What’s your learning?