Showing posts with label flow. Show all posts
Showing posts with label flow. Show all posts

Taiichi Ohno's workplace management

is an excellent book by Taiichi Ohno (isbn 978-0-07-180801-9). As usual I'm going to quote from a few pages:
When I was a middle school student in the old system, we studied the Chinese classics, and during this class we learned from the Analects of Confucius. In these writings Confucious says, "The wise will mend their ways" and "The wise man should not hesitate to correct themselves."... Confucius was saying that we should change gracefully... I think his words mean that in the end it is not good if you hold onto your ideas too strongly and try stubbornly to justify them.
When we said we would set up a centralized grinding operation, one experienced worker said, "No, we tried that during the war, but it failed. That's why we do it the way we do now." [I said] "I did not see it fail during the war. Show me again how it fails. If I am persuaded by this, I will let you continue doing it the way you do it now."
If you asked me, "What is the most important part of production control?" I would say it is to limit overproduction.
The kanban was a slip that indicated how many pieces they were coming to get, so that if they were going to take ten parts this became a production instruction slip directing the production line to make ten pieces.
When lot sizes are small, you need to do changeovers more frequently.
Stopping the line causes a great loss, so this forces us to think, "How do we keep them from stopping the line?" and this results in more and more quality kaizen.
You can only really tell what is better based on results.
Accounting cannot do any cost reduction... The shop floor reduces inventory. This money goes to the bank... Instead, accounting thinks it just needs to allocate cost savings targets.
There is something called standard work, but standards should be changing constantly. Instead, if you think of the standard as the best you can do, it's all over. The standard is only a baseline for doing further kaizen. It is kaiaku if things get worse than now, and it is kaizen if things get better than now. Standards are set arbitrarily by humans so how can they not change?
You must create a standard for comparison.
Drop a nut once and pick it up. Working at the average time is like trying to catch the nut halfway because letting it drop all the way down takes too long... There is no such thing as average value in this world.
Do not seek to follow in the footsteps of the old masters, seek instead what these masters sought. [Matsu Basho 1644-1694]
Once he asked me how the terms kaizen and kairyo (reform) were differentiated in the West. I said that while kaizen means to make improvements by using brains, kairyo means to make improvements by using money, and that in the West, most managers only think of improvement in terms of money. [Massaki Imai]
Let the flow manage the processes, and not let management manage the flow.
The aim of kanban is to make troubles come to the surface and link them to kaizen activity. I tell people, "Let idle people play rather than do unnecessary work."
The production line that never stops is either excellent or terrible.
Costs exist to be reduced, not to be calculated.

smart swarm

is an excellent book by Peter Miller (isbn 978-0-00-738297-2). As usual I'm going to quote from a few pages:
As successful foragers return to the nest with seeds, they're met at the nest entrace by foragers waiting in reserve. This contact stimulates the inactive ants to go out. Foragers normally don't come back until they find something. So the faster the foragers return, the faster other ants go out, enabling the colony to tune its work force to the probability of finding food.
Instead of attempting to outsmart the desert environment, the ants, in a sense, were matching its complexity with their own.
Instead of trying to keep fine-tuning a system so it will work better and better, maybe what we really ought to be looking for is a rigourous way of saying, okay, that's good enough. [Deborah Gordon]
If a scout bee was impressed by another scout's dance, she might fly to the box being advertised and conduct her own inspection, which could last as long as an hour. But she would never blindly follow another scout's opinion by dancing for a site she hadn't visited.
J. Scott Turner considers the mound's function as a respiratory system so essential that the termites couldn't live without it. In a sense, he argues, the mound is almost a living part of the colony.
If individuals in a group are prompted to make small changes to a shared structure that inspires others to improve it even further, the structure becomes an active player in the creative process.
Unlike our systems, which are tuned for efficiency, the termites' systems have been tuned for robustness, which they demonstrate by building mounds that are constantly self-healing.
What really made the lights go on was the realization that termites don't pay attention to the environment itself but to changes in the environment.
Not only does this complicated structure represent an indirect collaboration among millions of individuals, it also embodies a kind of ongoing conversation between the colony and the world outside. The mound might look like a structure, but it's better thought of as a process.
We should think of it [the termite mound] as a dynamic system that balances forces both inside and outside its walls to create the right environment for the termites.
When you feel like you belong to something, it gives you so much more freedom and so much more energy that might otherwise be used up in anxiety, to do other things.
On January 12, 2006, several hundred thousand pilgrims had gathered in a dusty tent city at Mina, three miles east of Mecca...
By noon... about a half-million or more pilgrims filled the Jamarat plaza in front of the bridge... The pressure inside the crowd was crushing... More than an hour later, victims were piled up seven layers deep: 363 men and women were dead.
"Those in charge need to remember the root cause of the problem: too many people trying to get through too small a space. The ingress rate at the bridge was 135,000 per hour. The thoughput rate of the pillars was only 100,000 an hour. You can't put a pint into a half-pint jug." [Keith Still]

kanban

is an excellent book by David Anderson (isbn 978-0-9845214-0-1). As usual I'm going to quote from a few pages:
The essence of starting with Kanban is to change as little as possible.
Failure to make a delivery on a promised date gets noticed much more than the specific content of a given delivery does.
Counter-intuitively, most bottleneck management happens away from the bottleneck.
Speed is most useful if it is in the right direction… If your priority is to find and reduce the constraint you are often solving the wrong problem... The dramatic success of the Toyota Production System (TPS) had nothing to do with finding and eliminating bottlenecks. Toyota's performance gains came from using batch-size reduction and variability reduction to reduce work-in-progress inventory [Don Reinersten]
Kan-ban is a Japanese word that literally means "signal card" in English. In a manufacturing environment, this card is used as a signal to tell an upstream step in a process to produce more work. The workers at each step in the process are not allowed to do work unless they are signalled with a kanban from a downstream step.
Trust is a hard thing to define. Sociologists call it social capital. What they've learned is that trust is event driven and that small, frequent gestures or events enhance trust more than large gestures made only occasionally.
High-trust cultures tend to have flatter structures than lower-trust cultures.
The traditional approach to forming a commitment around scope, schedule, and budget is indicative of a one-off transaction. It implies that there is no ongoing relationship; it implies a low level of trust.
The more groups involved, the longer the meeting is likely to take. The longer the meeting, the less frequently you are likely to hold it…
Buffers and queues add WIP to your system and their effect is to lengthen lead time. However, buffers and queues smooth flow and improve predictability of that lead time. By smoothing flow, they increase throughput, so more work is delivered through the kanban system. Buffers also ensure that people are kept working and provide for greater utilisation. There needs to be a balance, and buffers help maintain it. In many instances you are seeking business agility through shorter lead times, and higher quality partly through lower work-in-progress. However, do not sacrifice predictability in order to achieve agility or quality. If your queue and buffer sizes are too small and your system suffers from a lot of stop-go behaviour due to variability, your lead times will be unpredictable, with a wide spread of variability. The key to choosing a WIP limit for a buffer is that it must be large enough to ensure smooth flow in the system and avoid idle time in the bottleneck.
The first principles of Kanban are to limit work-in-progress and to pull work using a visual signalling system.
You need slack to enable continuous improvement… In order to have slack, you must have an unbalanced value stream with a bottleneck resource.
The width of a bottle's neck controls the flow of liquid into and out of the bottle. We can pour quickly from a wide neck, but often with a greater risk of spillage. With a narrow neck, the flow is slower but it can be more precise… In general, a bottleneck in a process flow is anywhere that a backlog of work builds up waiting to be processed.
As we all know, there really is no such thing are multi-tasking in the office; what we do is frequent task switching.

The principles of product development flow

is an excellent book by Donald Reinersten (isbn 978-1-935401-00-1). As usual I'm going to quote from a few pages:
Operating a product development process near full utilisation is an economic disaster.
When we emphasise flow, we focus on queues rather than timelines.
Almost any specialist can become a queue.
We grow queues much faster than we can shrink them.
When queues are large, it is very hard to create urgency.
Queues amplify variability. Moving from 75 to 95% utilisation increases variability by 25 times.
Sequential phase-gate processes have inherently large batch transfers.
Large batches encourage even larger batches.
Reducing batch size is usually the single most effective way to reduce queues.
Companies inevitably feel they can computerise this whiteboard, however, they almost always create a more elegant but less useful system.
The speed of feedback is at least two orders of magnitude more important to product developers than manufacturers.
The human effect of fast feedback loops are regenerative. Fast feedback gives people a sense of control; they use it, see results, and this further reinforces their sense of control.
Homeostasis is the tendency of a system to maintain its current state.
In product development, our problem is virtually never motionless engineers. It is almost always motionless work products.
Opportunities get smaller with time, and obstacles get larger.
The scarcest resource is always time.
To align behaviours reward people for the work of others.
It has been said that one barbarian could defeat one Roman soldier in combat, but that 1,000 Roman soldiers could always defeat 1,000 barbarians.
The Marines, and all other elite organisations, maintain continuity in their organisational units.


my kanban 1's board game

Here's a slide deck explaining the essence of my kanban 1s board game. Jon Jaggers Kanban 1s Board Game[フレーム]
  • You can play an early session with no clips so the players can see how inventory builds up (you can also push done story-cards to the next edge's corner, rather than waiting for them to be pulled).
  • The clips that hold the story-cards are a crucial part of the game. They make it a kanban game.
  • You can limit the number of clips per edge to create a natural work-in-progress (wip) limit.
  • You can add a new rule: players can also spend a 1 to split a story-card in two, eg a 4 into a 3 and a 1 (assuming they have a spare clip).
  • You can record the day a story-card comes off the backlog, and also the day it gets to done and thus measure the cycle time.
  • You can simulate scrum-style discrete sprints.
  • You can vary the number of dice at different edges.


Butter sighted at Olve's house

This is a photo of a pack of butter belonging to my good friend Olve Maudal. Olve has exactly 157 packs of butter in his house right now. All safely housed in his new super-sized fridge. Many of his 157 packs have been flown in specially by relatives visiting from abroad. Olve would only allow one pack out of the fridge for the photo. Even then he insisted it be taken out under the watchful eyes of the two security guards he's specially hired to guard the fridge - Lars by day and the other Lars by night. Well, you can't be too careful right now. Butter is selling for crazy money on the black (or should that be yellow) market.

Yes, it's just one small example of the butter shortage here in Norway at the moment. Apparently the cause is a new fat-rich fad-diet sweeping the population combined with the seasonal tradition of making butter-rich Xmas cookies.

Shortages like this are, as Stephen Fry might put it, quite interesting. At one point there was probably a very mild shortage. Word of the mild shortage started to spread (sorry) and anyone buying butter bought a few extra packets just to be safe. The shortage got a bit worse. Word of the worsening shortage spread further and faster. People bought even more. A self-fulfilling dynamic was thus set in place. Soon the shelves were stripped of all butter.

The shortage the customers are experiencing is, no doubt, fractally mirrored by the shops selling (or rather not selling) butter. Butter wholesalers just don't have enough butter to meet the orders from shops. Shops that get any butter get less than they ordered. Any butter the shops do get is bought in a flash (but only by relatively few people because of the bulk butter buying behaviour) and they're out of stock again. You can imagine the shop keepers pulling their hair out in exasperation. If only they could get more butter they could make a small fortune. But right when there's the most demand they have none on their shelves! They increase the size of their wholesale reorder hoping to cash in.

What will happen in a few weeks time? One possible (perhaps even likely) outcome, is that the wholesalers will finally get enough butter to meet their over-inflated orders. The shop keepers pile the butter onto their shelves and wait for the Krona to roll in... Some of the butter is sold. But not very much. After all, Xmas is now over. The fat-rich fad-diet has gone the way of all fads and the glossy magazines are now preaching a low-fat diet. And lets not forget that a fair percentage of the population has, like Olve, over 100 packets of butter in their new fridges. They're certainly not going to be buying butter any time soon.

The shop keepers then face the daunting prospect of vast butter-walls sitting unsold on their shelves, fast approaching its sell-by date. Lowering the price doesn't help. It all has to be thrown away. Again the same thing will be fractally mirrored at the smaller scale. Lots of people, such as Olve, will have more butter than they can possibly use in time. They too will have to throw out loads of butter as it goes past its use-by date.

The same lurching from one extreme to another can happen when the number of people trying to make phone calls starts to approach network capacity. People can't get through. So they try again. And when they do get through the line gets dropped. So when they do get through they stay on a bit longer. It happens on roads too.

It's dangerous to run systems at full capacity. They reach a tipping point and topple into a death spiral. Busy work and inventory pile up. That causes even more busy work and even more inventory. But almost no butter is being bought or sold. There is no flow.

flow = speed x density

I attended the ALE conference in Berlin last week. It was excellent in many many ways. Lots of participants have written blog entries and I thought I would write a short one about just one of the many things I thought was really great. It was the above graph which Karl Scotland drew in his talk, The Science of Kanban.

Karl used this graph in the context of traffic.
  • The green line is traffic Speed and it rises (to the right) from zero at the bottom left.
  • The red line is traffic Density and it rises (to the left) from zero at the bottom right.
  • The black line is traffic Flow and equals Speed x Density.
Speaking to Karl afterwards we discussed the analogy:
  • Speed = cycle time. The time it takes from the moment a piece of work enters the system to the time it gets to Done.
  • Density = work in progress. The amount of work that has entered the system but hasn't yet got to Done.
Karl also pointed out two feedback loops.
  • Start on the density line (red) at zero (bottom right) and increase the density (move up and to the left). For a while increasing the density increases the flow. Increasing the flow causes the density to reduce. Thus you have a stabilizing feedback loop helping to increase the flow.
  • As you continue to increase the density you drop over the top of the flow-curve.
  • Now as the density increases the flow decreases. And decreasing the flow causes the density to further increase. Thus you have a different destabilizing feedback loop helping to decrease the flow.
Simple and effective. Thank you Karl.

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