JKE Update: One Million Spark Plugs per Day

By Ron Pereira Updated on September 25th, 2020

Today, on day 4 of my Japanese Kaikaku Experience, we visited the NGK spark plug factory where they produce approximately 1.1 million spark plugs per day.

On our first day Brad, our guide, told us to focus on the good.  He challenged us to think and not judge.  Unfortunately, my arrogant American ways got the best of me for part of the tour today.

Where are the kanban?

You see, I was asking questions like where are your kanban?  What is the water spider schedule?  You know, basic lean stuff.  Well, for the most part, the NGK guys responded with comments like, “We don’t work like that, etc.”

This began to frustrate me as I thought, “How can one of Toyota’s top suppliers not use basic lean principles like kanban?”  Then it hit me like a ton of bricks.

Mean, Lean, Flowing Machine

These guys don’t use kanban because they don’t have too!  One of the basic tenets of lean is to flow, flow, flow.  Then, when you can’t flow – pull.

Well, NGK may very well win the award for best flow of all time.  Initially, I labeled these guys as kings of push.  You know, they pushed material from process to process.

Then I got off my high horse for a few moments and realized one thing.  If they are really pushing… where was all the WIP?  When mass producers push inventory one thing is consistent – you will find mounds of work in process all over the place.  Well, this wasn’t the case today at NGK.

You see, they have things so balanced and flowing so well according to what the customer wants they just turn things on and let it roll.  Don’t get me wrong they have a tremendously difficult task.  The process to make a spark plug is not exactly simple.  But near perfect flow is how I would describe what I witnessed today.

It was also a humbling experience as I realized I have so much more to learn about lean.

Equipment Makers

NGK builds most of its own equipment.  We weren’t allowed to take pictures but let me just say they have some awesome machines.

For example, the last step of the entire process is to put the spark plugs into little boxes.  This home grown boxing machine was a thing of beauty.  It was simple, yet complex.  It was like nothing I have ever seen and I have seen lots of very expensive boxing machines that jammed more than they boxed!


If you build a million of anything one thing is certain.  You better have reliable equipment.  After a few minutes in the plant I noticed a theme.  The little letters “TPM” appeared again and again on bullentin boards and kaizen newspapers – which were everywhere!

Brad, our guide, also helped me identify numerous examples of autonomous maintenance (daily checks) sheets.  Since they were in Japanese I couldn’t read them but it was clear they were being used as things were hand written on them.

Interestingly enough, it didn’t seem like they were using a maintenance management system.  They did things the old fashioned way – with pencil and paper.

During our Q&A one person asked if they would apply for the Japanese TPM award.  The NGK manager firmly answered no.  He went on to say that they are not interested in awards like this… instead they only want to use these methods to take out waste and reduce costs (a means to an end was his exact words).  How refreshing is that?

Where are the safety glasses?

If you walk around a plant similar to NGK in America without safety glasses you will likely be pounced on within minutes.  Well, if there was one theme I noticed this week in Japan it’s that safety glasses are out!  No one, and I mean no one, wears safety glasses, hard hats, etc.

One may think this is nuts.  I mean it’s just not safe.  One may then ask the question… well how is their lost time accident rate at NGK?

NGK explained they have 4 levels of injuries.  The first level is reached when someone gets something like a scratch.  The second level is when someone gets injured but doesn’t need to take any time off work.  The third level is when someone gets hurt and must take time off from work.  The fourth level is when someone is injured in a permanent manner.

NGK told us they had 1 reported injury in 2006 (the latest data they shared).  Naturally, we asked which level this was – 1, 2, 3, or 4?  I figured they would say 2 or maybe 3.  They responded 1.  So they had one scratch like injury in 2006!

I am not proposing we do away with safety glasses and hard hats in America.  But it does cause me to ponder if we are really on the right course.  What can we learn from Japan?

Other Tidbits

There are so many other things to share.  Like how excellent these guys are at creating a visual factory.  And the 5S level in this plant was just spectatular.  The floors shined.  Lastly, the manager we talked to continued to stress how important it was for them to continue to improve productivity and quality.

Speaking of quality, I asked a NGK engineer what their defect rate was on one of their complicated processes during the tour.  He explained that on the smaller sizes they have no defects – ever.

He then got this very serious face as he explained that on the larger sizes they do have problems.  How big of a problem I asked?  Try 10 PPM.  In other words, for every million spark plugs produced 10 are defective.  I felt so sorry for them!

What a day.  What a week.  More to come on my amazing experience here in Japan.

  1. Brian Buck

    March 25, 2008 - 2:10 pm

    What is the water spider schedule?

  2. Ron Pereira

    March 25, 2008 - 3:18 pm

    Hi Brian,

    I am not sure if your question is what is NGL’s water spider schedule… or what is a water spider schedule? I will answer both.

    A water spider schedule is a schedule of how the water spider (sort of like a lean materials handler) moves about the shop. When things are paced to takt time the delivery of parts and pickup of finished goods normally operates like clock work.

    NGK didn’t seem to operate in this manner. However, they did have a material handler moving about as needed.

    Hope this answered your question?

  3. Brian Buck

    March 25, 2008 - 4:59 pm

    It did Ron, thanks.

    Great site by the way. All of your Japan articles have been inspiring.

    I have also found a tremendous value in your e-book.

  4. Ron Pereira

    March 25, 2008 - 7:49 pm

    Thanks for the kind words Brian. I really appreciate them. Please feel free to share the ebook with as many people as you’d like. All the best.

  5. Stephen Edwards

    March 29, 2008 - 10:59 pm

    Brian – Just returned from my first visit to Japan. While I was there I toured several Toyota manufacturing plants and experienced the same response as you relate. Every moment I was in a factory filled me with awe and respect for TPS. Not even being a practioner of TPS (I’m with Toyota Industrial Equipment Mfg) prepared me for the total immersion into the Toyota Way I encountered while there. Very difficult to articulate and I’m finding it continues to benefit me in ways I never expect, even after being home for a month!

  6. Srikanth K Reddy

    October 28, 2008 - 12:14 pm

    Ron, i am really amazed by all the facts from your Japan visit. Reading them i had one doubt in my mind, who is the best manufacturer in the world ? is it Toyota?

  7. Ron Pereira

    October 28, 2008 - 2:42 pm

    Thanks Srikanth. I am not sure who is the best as it would depend on what criteria you were using. With that said, I am not sure there are many better than Toyota! But they have had their own issues related to quality and recalls… so they aren’t infallible by any means.

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