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Adventures In TPS Learning, Decreasing Muri

Aug 25, 2014 | Posted by Ben Thompson


It seems more often then not that seemingly ‘simple’ problems in a process hold us back rather significantly. Many times I have found that these ‘simple’ problems are muri, the waste of overburden, related. For example last week I did a small kaizen with my production team with fastening floors in our truck bodies at Durabody . It was known for a little while that our floor chalk wasn’t the easiest to see but it was put on the back burner for a while. Big mistake! Probably one of the simplest and least expensive kaizens you could have and with some pretty good results.

You see it was a morning like any other, coffee in hand sat down at the computer, checked my email accounts and wham, one fateful email from our fearless leader here at Durabody Trevor Thompson, no relation to myself, with three words and a picture; high visibility chalk. This prompted a road trip to the local Home depot where I acquired these little guys.


So what will this high visibility chalk really do for us? Sally Silveo a Continuous Improvement Team Lead at Barry Callebaut in Europe said it the best in a recent LinkedIn discussion,

“ as your process involves locating floor fastening screws, it surely requires visual travel and visual control […] visual travel ( moving the eyes towards the location of the object ) and visual control ( fixing the eyes on the object ) […] Having a high visibility chalk will lessen the elapsed time for visual travel to locate the screw. This can be just a few TMUs ( time measurement units), but if you consider the number of times the cycle is repeated during the entire process, then this decrease in work element time will deliver a considerable decrease in the cycle time of the process.” Sally is scientifically saying that the high visibility chalk should reduce eye strain and free up the mind to work faster better and safer because it is experiencing less burden when using the high visibility chalk versus the blue chalk. Sounds like a reduction in muri may occur with this simple chalk swap.

Well Sally knows her stuff she hit the screw, right on the head. My team and I tested both chalks in both well lit and and poorly lit conditions and the results positively correlated toward the high visibility chalk. Firstly, in well lit conditions the blue chalk  had a lowest repeatable time of 12 seconds per screw and a fluctuation of 9 seconds. This is a pretty good cycle time per screw, until you put it up against the 7 second lowest repeatable with 8 seconds of fluctuation.

Try this on for size, can you see both lines?


I first posted this question on twitter with this picture last Friday, the first comment received was “There are two lines??” rather priceless. The blue line believe it or not is about two inches left of my right foot, not very visible as you can see.

All of that was in well lit conditions, so this is where it gets fun. In a poorly lit truck body, wiring still to be done for the lights etc., the blue chalk performed poorly with lowest repeatable achieving only 13 seconds per screw and a staggering fluctuation of 25 seconds. The lowest repeatable for the high visibility chalk jumped to 9 seconds per screw but with a fluctuation of only 6 seconds, a very similar result to our well lit results showing us that this high visibility chalk has some merit to it. Sally mentioned that even though it may just be a few time measurement units the vast number of cycles completed would make those few unit cause a significant impact. Well, Sally was right again; though we are only shaving ~5 seconds off each floor screw, the average body has 300+ floor screws. That factors out to 1500 seconds or 25 minutes per body, which in turn equals a kaizen victory.

I’d like to take these last few lines to thank firstly my team at Durabody and secondly  everyone from the Linked In groups Lean Six Sigma and TPS Principles and Practice for all of your questions, comments, ideas and support; all of you guys made this little kaizen a lot more fun and successful then it would have been. Lastly, I’d like to thank my mentor, boss and friend Matt Elson for teaching me to trust the process of TPS and how to,






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