Dear Gemba Coach,
I’m a six sigma black belt and have now been ask to do lean. I’m reading the literature and there’s a lot to absorb. I’m not sure where to start with my team. Any advice?
The analytical tools you’ve used as a six sigma black belt will serve you well, but one of the main differences I can see between the two approaches is that where six sigma aims to solve a problem, lean aims to develop the spirit of continuous improvement. You need to get your mind around this rather big change for much of the literature to make sense, and the best illustrations can be found in Masaaki Imai’s Gemba Kaizen and in Jon Miller’s Creating a Kaizen Culture.
There are three broad aspects specific to lean to establishing continuous improvement habits in your team:
- Continuous improvement of visual control
- Continuous improvement of individual skills
- Continuous improvement of the flow of work (the process)
Visual control is very specific to lean and needs to be learned – often from scratch. Unfortunately the literature is not much help there because although it mentions it frequently, it doesn’t quite say how. The old time senseis use to badger us incessantly on whether we could, at a glance, distinguish normal situations from abnormal situations.
Visual control can be as simple as tape on the floor to highlight an area, say for buffer stock, which shows immediately that one extra box is overflowing. Visual control can be a kanban that visualizes the flow of jobs through your team. Visual control’s goal is that we see together, we discuss together, so we act together.
But the lean point is that visual control should be constantly improved, in order to improve the detail of problems we look for. For instance, if we paint lines on the floor to identify a buffer zone, the sensei would ask us to draw spaces for each individual container. If we’d set up a red bin to highlight defective parts, the sensei would ask us to draw levels so that we could tell whether the number of defectives right now was normal or abnormal. If we set up a team kanban in an engineering office, the sensei would ask us to make it individual kanban boards and so on. The essence here is that the work environment continuously evolves until work is perfectly intuitive and can be understood by all at a glance.
As visual control improves, so does our understanding of problems. Problems are the principal training tool in lean as people’s expertise is developed by solving problems, and their ability to work with others is developed by solving problems across organizational boundaries. The difference I can see with six sigma is that you’re not expected to solve the problems yourself (with the help of your team). You’re expected to help your team members to solve their problems in order to develop their competences.
Your six sigma training should help you to understand problems in detail and do all the measurement and clarification necessary to frame it correctly. But then, rather than “solving it” in lean, we’ll ask “why?” and “why?” until we’ve figured out which exact part of the technical process we handle poorly, or which special cases we’re not so familiar with and so on. Once you’re figured this out the “problem” becomes a straightforward issue of training. Whether by codifying work standards better or continuing to solve similar problems, the aim of lean is to develop capability by growing the team’s expertise in handling their process in unusual or difficult cases.
By example, think of the damage vendors can do to overall process efficiency. Dealing better with difficult suppliers is a complex problem because there is not one cause, but many, probably a specific case for each supplier. Teaching project leaders or procurement officers to improve the regularity of supply is a core capability, which requires them to understand how their system adds to the vendor’s internal problems and how to help vendors deliver good parts on time rather than blame them for poor delivery. You will grow this capability as you train every one of your procurement people to better understand vendor specificities – never an easy job.
Biggest Barrier Going from Six Sigma to Lean
Finally, “process improvement” in lean tends to mean something different than in six sigma. As I understand it, six sigma is focused on reducing variation… to six sigma levels. Nothing wrong with that. However, in lean our obsession is to improve the flow of work by reducing batches through reducing set-up times. Getting closer and closer to takt time is what “leans” the process and what reveals more detailed problems (and back to the first point).
I can’t emphasize enough the importance of set-up reduction in lean thinking, to understand process issues such as:
- Lack of understanding of sales pace and production pace
- Large batches
- Broken up, complex interlocking steps
- Poor inter-process logistics (batching up the transport)
Mastering variation in technical processes is a huge part of solving overall process performance issues, but not an aim in itself (other, than, of course inasmuch as it affects quality). Leaning a process is essentially about making work flow at the customer’s rhythm.
The upshot of the shift from solving discrete problems to developing a spirit of continuous improvement is that, in my experience, six sigma instincts tend to be to freeze the process once we’ve got it to work as we want it to – to seek static efficiency. Lean looks for dynamic gains, a very different source of performance. Lean tools are about teaching people to change:
- Change their work environment for ease of work and better visual control.
- Change how they do technical steps to better adapt to specific cases.
- Change tools and stations more often to have greater flexibility in both product mix and volume.
I remember a Toyota document detailing how they implemented lean in one of their plants decade after decade, and their explicit aim was: reform manager’s mind. The biggest difficulty you’ll probably face in switching from six sigma to lean is not the understanding of the tools, but the change of heart and mind about the kind of progress we’re after. Lean performance comes from the dynamic improvement, not static efficiency.