This last post of my series looks at fluctuations that originate downstream from your location. In other words, how to reduce fluctuations originating from your customer. Granted, this often is the most difficult one, as you usually have not so much influence over your customers (unless you have a monopoly). Let’s have a look.
Fluctuation
Reducing Fluctuations on Your Shop Floor
Fluctuations can also originate within your area of responsibility. In my previous post, I looked at how to reduce fluctuations coming from upstream. In this post I look at your shop floor. Using the source-make-deliver structure, this post is about reducing fluctuations at “make.”
Reducing Fluctuations Upstream
This post will list a number of tools that can help to reduce fluctuations. They can reduce fluctuations in the material flow, including its inventories and the durations and lead times. Since reducing fluctuations (mura) is an underlying important idea throughout lean manufacturing, a lot of tools can help. And, depending on how you interpret tools, this list is not even complete.
Structure for Reducing Fluctuations
This post looks at how to reduce fluctuations (mura) in manufacturing. It is a continuation of the previous post that looked at why fluctuations are so bad. Be warned, tackling fluctuations is often a tedious task that never ends, but it one of the important fundamentals for lean manufacturing. After all, the more stable a system runs, the more efficient it is. Leveling is one major method to reduce fluctuations that focuses on the production schedule. Line balancing is another one that focuses on the work content.
Why Are Fluctuations So Bad?
Fluctuations are bad for manufacturing. In lean, unevenness is one of the three evils, besides waste and overburden. In this post I will give you an introduction to fluctuations. One option to handle fluctuations is decoupling, but this addresses only the symptoms and not the cure. In my next post I will show you how to actually reduce fluctuations.
When and How to Use Extra Kanban
Kanban (and pull systems in general) are a beautiful way to manage production. While the number of kanban cards should be verified periodically, for certain situations, however, it may be sensible to have additional kanban prepared. These extra kanban are added to the system on short notice to alleviate symptoms of other problems. However, please do not see this as a new and cool additional feature to your kanban system. Instead, if you have to use extra kanban, then something is going wrong. Such extra kanban are only an emergency fix and do not solve the underlying problem. Still, in some cases you do need an emergency fix. Let me explain:
A Small Dice Game for the Kingman Formula
In a previous post I wrote about the relation between utilization, fluctuation, and waiting time, and its approximation by the Kingman formula. Let me show you a quick and easy dice game where we simulate a supermarket checkout to let participants experience the effect of utilization, fluctuation, and the (worse) combined effect of both.