The Water Spider: What's in a Name?



By Jon Miller | Post Date: November 22, 2006 9:46 AM | Comments: 15

One of the things that keeps Lean manufacturing from being boring to the amateur linguist is the many odd-sounding words that make up the Lean lexicon. Kamishibai. Heijunka. Pareto. Yamazumi. Takt. Andon. Jidoka. Kaizen. Pokayoke. Gemba. And don't even get me started on the acronyms.

Then there is this thing called the Water Spider. The Water Spider position is often confused with a simple material handler or an entry level "go fetch" person. Far from it, the Water Spider needs to be thoroughly familiar with the materials, tools and methods of the process they are supporting. My teachers used to say the Water Spider role was a "right of passage" to becoming a supervisor. The Water Spider is an honored and critical role in making continuous flow and a smoothly functioning Lean system a reality.

But what's in a name? Why Water Spider? People often think this word comes from the insect that skims the surface of the water (water strider) but technically this is not correct. The water spider is the beetle that moves about inside the water, not on the surface. What makes this confusing is that the word "mizusumashi" in Japanese at times refers to both.

A good way to remember this is that while the water beetle dives into the water (dives into the process, gets close the the cell, even goes into the cell to do occasional relief work for operators) the water strider skims across the surface and does not go under the water (close to the process). The Water Spider in Lean manufacturing must be intimate with the process or cell they support, not just a pick-up-and-drop-off material handler.

Who cares? Is this distinction important? Why are we talking about beetles?

The similarity between the Water Spider (the person who moves about the factory or assembly line) and water beetle (swims under the water) was explained to me as how they move in the water or move about the factory. This explanation by itself might lead to the misunderstanding that the Water Spider is a typical material handler.

But here's another theory. Water spider is “mizusumashi” in Japanese. This is written phonetically as みずすまし or in kanji script as 水澄まし. The word literally means "make water cleaner" or "purify water". I don't know if this little beetle actually cleans the water or not. You would have to ask an entomologist. The water beetle does have little broom-like fibers on its rear legs, so perhaps that's how it "cleans the water". Or perhaps it was noticed that water spiders only lived in the clear water so they were given credit for making it clean.

If we suppose that the water spider (beetle) makes the water clean or keeps it clean, the water spider (human) also keeps the flow in the factory or in the flow line clean and smooth by taking on the occasional tasks (tasks that do not happen every cycle, such as material replenishment or making shipping containers). A clear process flow and defined work sequence (clear flowing water) is also a requirement for designing the workload of the Water Spider position.

So let's have a look at these little clear water bugs. They look a bit like cockroaches so don't follow these links if you are squeamish. Here is a glossy black water spider swimming in the water. Here is a more colorful water spider posing for the camera. This water spider is resting (cockroach alert) on a piece of wood sticking out of the water.

Mike Wroblewski at the Got Boondoggle? blog wrote a great entry a while ago about his personal experience doing the work and doing kaizen of the Water Spider job. Check it out.

The Water Spider role is very important and there is a lot more that could be said about the Water Spider in Lean manufacturing, but perhaps another day.

You’re so about standard work but what is this terminology. It's not standard. I went to Google and entered water spider alert your sight is the only sight with info on this term. Since this word is not standard terminology, perhaps you should ensure that the people receiving standard work procedures containing this term know the definition. I thought our plant was infested. Is this term completely proprietary to KAISEN?

Poster: emanon | Post Date: January 25, 2007 11:50 AM

It is standard. Just not as well known as some other standard terms.

If you want to find other references to "water spider" as used in the Toyota Production Sytem, Lean and kaizen, enter water+spider+lean in the Google search field.

Do not use Google Alerts, this only gives you news or newly indexed pages.

Poster: Jon Miller | Post Date: January 25, 2007 5:01 PM

There is another native English-speaker that also speaks Japanese, whose name is Fred Harriman.
He has a site on Kaizen where says that "water SPIDER" should be more properly called "water STRIDER".
But it do resembles a spider, not a beetle.
http://www.fredharriman.com/resources/WaterSpider.htm
I love both, Jon and Fred, for bridging the language gap in these issues. Perhaps they are anecdotic, but doubtless interesting.

Poster: Ernesto Jorge | Post Date: May 18, 2007 11:09 AM

I've met Fred. He's a good guy.

I still hold that the water spider is a beetle that swims in the water, rather than on the water like the strider.

If there are any entomologists reading, they can resolve this debate.

Poster: Jon Miller | Post Date: May 18, 2007 12:39 PM

Can you explain how Pitch is calculated and used for water spider function?

Poster: Frank M Stroscio | Post Date: June 14, 2007 7:33 PM

Hi Frank,

The short answer is that pitch is a multiple of takt time, often tied to the pack out quantity, but basically any round number multiple that allows for a set interval of work to be performed by the water spider in synch with the paced production line.

For example, if a product is produced every 90 seconds (takt time) and the container holds twenty units, the pitch increment would be 1,800 seconds or 30 minutes minutes.

The water spider would make their round to that point every 30 minutes to pick up finished parts and move them to the next process. They would also drop off materials needed or perform other tasks to fulfill needs of that process, based on consumption of parts over the 30 minute pitch.

It gets more complex when you are delivery materials to the line that come in non-standard packaging (returnable plastic containers from local suppliers with one quantity standard, cardboard boxes from overseas suppliers with a different quantity) since these will generally not have the same common denominator. I have been a situation where there is not enough space on the line to store large parts and the water spider needed to adjust the pitch to deliver parts every 2/3rd full pack out quantity, and we ended up having 2 water spiders for 3 lines.

Also, when you combine material pick up and drop off into one cycle, you have to determine pitch based on what the standard work of the operator will be based on desired storage quantity and space on the line, and so forth.

Jon

Poster: Jon | Post Date: June 15, 2007 7:30 AM

Cummins also uses the term water spider in their lean manufacturing.

Poster: Ricardo Petra Abba | Post Date: December 6, 2007 5:49 PM

i am a water-spider, my jobs not easy.

Poster: graeme houston | Post Date: August 17, 2009 10:50 PM

Hello,
I am a little confused. What kind of task the waterspider should do in addition to the material handling? Some examples ?

Poster: Onni | Post Date: December 21, 2009 3:23 AM

Hi Onni

Thanks for your question. The job of the water spider is typically focused on material replenishment but can include other brief bits of occasional work. Mainly this includes filling in for workers who need to leave the line for short periods and assisting during changeovers that require several people to coordinate their work on different areas of the machine. They key is to keep the main line running smoothly.

The team leader or line leader should have enough time to address more time-intensive support actions such as training or andon response.

Poster: Jon Miller | Post Date: December 21, 2009 5:22 PM

Thanks Mr. miller

I am trying to focus our waterspiders to do only the material replenishment and to cut out everything else. Of course there is also the evacuation and other things like that. In our case the water spider is really busy doing the replenishment and there is no time to do any filling for the operators. I can't see the point in any filling for the operators. What I mean is that the really important material providing work interrupts too much if the WS does stuff like that. So it doesn't fit my picture where I try to kill all the red time. Don't get me wrong I am just trying to understand the idea in this thing and possibly get a new points of view.

Poster: Onni | Post Date: February 26, 2010 12:08 AM

Hi Onni

Thanks for your comment. It's a good question. I've tried to clarify here

http://bit.ly/ajKlaj

Poster: Jon Miller | Post Date: March 15, 2010 12:45 AM

Hi,

what is the water spiders defense mechanism???

Poster: emily | Post Date: May 16, 2010 9:32 AM

What I learned about ws is that they also keep an eye on the processes & report on any delays or disruptions if the material has not been used up that way bringing in attention to clearing the blockages & keeping the flow going. Any addition to this ?

Poster: Rajan Bhagwat | Post Date: February 4, 2011 1:52 AM

Hello it's WS part of waste? if we add more operators our product price go higher so the WS it's necessary?

Poster: Joe | Post Date: February 7, 2011 2:24 PM
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