Aaron J. Crowley

Crowley’s Granite Concepts

Some years ago, our guys were unloading slabs from a delivery truck out in the parking lot when the forklift ran out of propane. It happened from time to time, but this time it was a bit different… and a bit embarrassing. 

The usual flurry of activity swapping tanks was strangely absent so I inquired of the driver the status of the replacement tank and he informed me with the “you’re not going to believe this” look on his face that ALL the spare tanks in the shop were empty.

So, there they were: forklift stalled in the parking lot, slab dangling from the clamp, and a sheepish looking driver twiddling his thumbs while someone raced to the nearby gas station to get a tank filled. 

I’d like to say that was an isolated case of oversight, but the truth is that before we started implementing a key Toyota manufacturing principle, it happened all the time. One day we’d be overnighting finger bits for the CNC.  The next day we’d be desperately calling Braxton-Bragg to have some 30 grit polishing pads delivered, ASAP.  The day after that we’d be racing out for propane.

It was the very definition of waste. 

The key Toyota principle that greatly reduced this chronic problem in our company is Kanban, which means signal.

Toyota’s version of Kanban is a system of storing and re-ordering critical supplies making it possible to always have enough supplies on hand without the excessive waste of last minute purchases and delays or the cost of over stocking (and loosing) excess inventory.

Step 1 is dedicating space for storage.  Whether it’s open storage racks or locking cabinets with shelves, each supply must have a “place” that is clearly labeled so that costly supplies aren’t misplaced or hidden. It’s a shame to spend $30 to overnight a $100 finger bit when you are out of finger bits. It’s a crime to spend that money because you can’t find the finger bits you’ve already bought (not that your tooling supplier is going to complain).

Step 2 of the system is to decide the minimum quantity that triggers re-ordering. This is a function of how frequently the supply is consumed and the time between re-order and standard delivery. If you use five 30 grit Viper pads per week and it takes 2-3 days to ship, the minimum acceptable quantity of 30 grit pads on the rack is three before re-ordering is triggered.

Step 3 is to create a signal that will trigger the re-order of the supply. This is communicating through visual cues that the minimum quantity acceptable has been reached and that re-ordering is necessary.  For example, empty propane tanks could be placed outside the production manager’s door, instead of along the wall where they are indistinguishable from the full tanks.  When the minimum number of full tanks is visible along the wall, the empty tanks are refilled before the remaining full tanks are consumed.

On the surface, Toyota’s Kanban might appear to be an overly simplistic system of managing the supplies that keep a stone shop running efficiently.  But that’s the beauty of it: it is simple enough to work in small stone shops, and large multinational corporations alike.

And the fact that Toyota’s profits regularly exceed the combined profits of Detroit’s big three year after year is yet another reason to consider Kanban for your countertop shop!

Aaron Crowley is a stone shop owner, author, speaker, and inventor of stone safety products. Contact Aaron by email at