Matt Hrivnak

Kaizen: There's always another future state


Although SMED was clearly developed during the 1900s, there are several cases from throughout history that can be referenced when trying to explain SMED.  The very basic idea of SMED, i.e. preparing and completing External setups while the machine/process is working on the current job, while streamlining Internal setups, etc. (if you are new to SMED, check out my article SMED…What is SMED?), can be seen in common processes that are around us.

The most common of these, which is more or less the cliche reference now because it seems every Lean trainer uses it, is the quick changeover of tires witnessed by Nascar and Indy racing fans at every race.  When you think about changing a tire, you think of several elements, like:

  1. Getting your tools
  2. Loosening 4/5/6 nuts
  3. Jacking up your car
  4. Pulling off the old wheel
  5. Putting on the new wheel
  6. Individually picking up the nuts and resetting them
  7. Tightening the nuts
  8. Putting the old tire in the trunk
  9. Putting your tools away

I assume it is something like that for most people.  Now, the quick connection they make here is that in an auto race, the pit crew is completely ready with their power tools, 1 guy jacks up the car, another takes the a) in cart racing, 1 (and only) nut off while maintaining it in the tooling head, b) in Nascar, the nuts are fixed to the wheel so only tightening is required, another guy removes and replaces the tire, and the nut(s) is tightened, etc.  You can see how that works.

Well, when thinking about SMED, there is a better example that I like to use.  So far, I’ve been a little on my own referencing this and some of my professors had a hard time grasping the concept of this being related to SMED.  Eventually, they saw my point and some of them use it in their classes to this day.  Unfortunately, this is not the most pleasant example of a SMED because of the nature of the resulting action, but it really gives a solid example of SMED.

Since the beginning of firearms, reloading has been a critical, essential, and frankly, a crucial aspect of warfare.  For any of you who are not that knowledgeable when it comes to the evolution of the gun, I’ll fill you in.  After the first couple hundred years of firearm development, the gun was stuck in a period of lackluster progression.  At the time of the American Revolution, muskets, a smooth bored muzzle loading rifle was the most widely used rifle in the world.  Due to the loading nature of the musket, a well trained infantryman could fire about 3 or 4 shots per minute.  Looking at this from a process standpoint, this gives us (assuming ~3 shots/minute):

  • Setup time:  20 seconds (includes aiming)
  • Cycle time:  ~1/10th of a second

The process for loading a musket, looks something like this:

  1. Stand the musket on its butt end, with the open barrel facing the sky
  2. Get out the gun powder (from a powder horn)
  3. Pour the required amount of powder down the barrel
  4. Put the powder horn away
  5. Get out the ball (i.e. bullet) (from a snap enclosed pouch)
  6. Put the bullet in the barrel
  7. Pull out the rifle’s ram rod from its casing on the side of the barrel
  8. Stick the ram rod in the barrel and push the bullet fully down
  9. Put the ram rod back in the side casing
  10. Pick up the musket
  11. Cock the hammer (which contains a piece of flint for creating a spark)
  12. Get out the powder
  13. Pour some more powder on the flash pan
  14. Put the powder horn away
  15. Aim the rifle
  16. Pull the trigger and hope the flint sparks and ignites the powder, firing the gun

That’s a lot to accomplish in 20 seconds. A small pictorial of an American Revolutionary War soldier is below (source:  http://www.americanrevolution.com/images/ContinentalArmy.jpg)

Like many processes, loading a rifle was held back because quicker changeovers were not possible due to technological issues and lack of progress in that area.  Slowly, the technology did improve and the flint-lock hammer was replaced with a preloaded percussion cap (like the kind you can buy in a toy store that makes a loud pop) that could easily be placed on a pin, before being struck by the hammer. 

 

This removed the clumsly action of pouring small amounts of gun powder into the flash pan while attempting to hold your composure.  Around the same time, ammunition companies began packaging the gun powder and the bullet in a paper encased packet that required the soldier to reach into only 1 compartment instead of 2.  The soldier would simply pull out the packet, bite off the end, and stick it in the front of the barrel.  So, after removing these small, but time consuming external elements, the process looked something like this:

  1. Stand the musket on its butt end, with the open barrel facing the sky
  2. Get out the paper packet
  3. Bite off the top and place the rest of it in the barrel
  4. Pull out the rifle’s ram rod from its casing on the side of the barrel
  5. Stick the ram rod in the barrel and push the bullet fully down
  6. Put the ram rod back in the side casing
  7. Pick up the musket
  8. Cock the hammer
  9. Get out the cap
  10. Place the cap on the pin
  11. Aim the rifle
  12. Pull the trigger

This type of rifle was used extensively around the time of the American Civil War.  At the same time, bullets were being improved through new packaging techniques that encased the bullets and powder in a metal shell that could be loaded into a moveable turret as you would expect to see on a revolver.  Much like the one pictured below:

 

It took another 25 years or so for this technology to be moved from pistols to rifles, but eventually, the rifle went from muzzle loaded to a pump action carbine to a bolt action rifle to the extremely fast firing machines guns used today.

With the development of the encased bullet, there was no longer a need for a percussion cap and the loading process looked something like this:

  1. Preload a small batch of bullets into a ‘clip’ (does not need to be done during battle)
  2. Attach the clip to the gun (again, the first clip can be done during down time)
  3. Aim the rifle
  4. Pull the trigger
  5. Repeat steps 3 & 4, as necessary

So, as they do, things progressed and eventually you end up with a mechanism like we see today.  Almost all of the external setup elements have been removed from the gun loading process, however, there is always room for continuous improvement. 

An Uzi (shown), can fire up to 1,200 rounds per minute (rpm)!  That’s 20 rounds per second or .05 seconds per bullet!!  Some machine guns are capable of firing at rates up to 3,000 rpm.

By advancements in technology that allowed external setup times to be reduced and internal setup times to be eliminated (and the streamlining of all other internal setup times), firearms have seen a throughput increase of 40,000% (using the musket and uzi as examples – (1,200 rpm / 3 rpm) x 100%)!  That kind of increase is unheard of in most manufacturing operations, but can be seen from time to time when dealing with automation.

 How about that for an example of how much improvement you can get from a SMED?!

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Comments (2) Posted by matt on Wednesday, May 14th, 2008


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