The Time of Day When Errors Happen

What time of day do mistakes most often occur?  That was a question we put to ourselves recently in an effort to see if we could find a pattern.

Everyone makes mistakes.  But what I would like to offer here is some research we did into finding the time, frequency and cause of mistakes in our press room.  True, they are not avoidable.  But as Bram Stoker said in Dracula, "We learn from failure, not from success!"  So I would like to share with you something insightful and practical that you can learn from and apply in your press room.  I don't present the solution, but a way of learning from it.

First of all, I would like to draw your attention to the chart below.  It shows the frequency of mistakes and press downtime associated with all mistakes made on our presses and auxiliary equipment.  We record and make a log of every mistake that takes place and this is the result of all the data compiled for two years.  I must add that we have a unique culture in our press room to honestly admit and record our mistakes.  But that's the subject for a future article...

Time of Day and Number of Mistakes and Downtime
The green line above shows the number of occurrences while the blue bar represents how much press downtime resulted.  Do you see a pattern?  Remember it is the culmination of 2 years data and it shows definite patterns.

Our press crews generally work an 8-5 shift and the occasional double shift.  What we see in the graph is a spike in errors first thing in the morning.  Then another spike between 11:00am and 12:00pm.  That one hour represents the highest number of  errors of any time of day and then tapers off the rest of the day until 5pm.  So the natural question we asked ourselves was - why?

We do not have any patterns in our printing schedule.  In other words, there is no print job that comes along on a daily basis at that time. In fact, none of the work we do starts or finishes at that particular time.  There was only one thing we found.


At 11:30 our press crews start a lunch rotation.  They go eat for 20 minutes and then return to the press.  This process starts in earnest at 11:30 and tapers off until finished at about 12:30.  During this time a little dosey doe takes place.  The crew members "cover" for one another while the press runs.  When we discovered this link, the cause was obvious.  The lesson?

  • Mistakes Occur When Crews Change
  • Running Short-Handed is Not Effective

It's hard to prove those conclusions without a wealth of data to back it up.  A short sighted viewpoint would conclude that there is little effect on press production.  And that running short handed may even save an employer some money.  But as the data shows, the employer pays in other ways.

So how do you avoid it?  Here I offer no solution as I said at the outset.  Everyone has to eat. People have to go the bathroom.  Inevitably, pressmen will have to cover for one another. Perhaps a better question would be "How do you minimize these factors?"

What We Did

We have since taken steps to ensure that the crew is never short handed.  Management comes out if need be to help relieve those going for lunch.  We also try to avoid lunch rotations when doing complex make readies.  Beyond that, it's hard to come up with a solution.  But hey, solving print problems was never easy anyway.

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