Would you know it if some of your mill rolls were out of specification? Specifically, would you know that your paper basis weight is higher than stated? What I call a “heavy roll.” Most web printers do not know this until it is too late. You’ve allocated five rolls for a job and your lead pressman assumes good count has been made at the end of the five rolls. Later in the day the bindery manager comes back to the pressroom complaining of being shorted.
“I used all of my issued stock and my waste was within plan,” said the lead pressman. “You must have gone over your planned waste at the binder.”
“My waste was just fine, but my good copies are 200 short,” replied the bindery manager.
Is this full and frank conversation common in your shop? Who’s right and who’s wrong? If the mill is stealing your copies, they may both be correct.
Counting on a web press without a dedicated counting system is generally a pressman’s gut combination of many data points; gross count, assumed yield per roll, perceived make ready and run waste, etc. Yield per roll is dependent on a fixed caliper and roll weight. The standard measurement for yield is the paper basis weight (PBW) assuming the weight and width of the roll are fixed. This is where it gets interesting.
Web rolls are purchased by the pound but you sell it to your customers by the copy which is ultimately tied to the length of paper on that roll. You also purchase a specific PBW from the mill which extrapolates to a certain length or yield per roll. This is what your lead pressman has in his head. However, if the actual PBW is higher than stated, 53# versus the stated PBW of 50#, then assuming roll width and roll weight are constant, the only other variable is paper length – it’s shorter!
Less linear feet = less yield
And this is how mills inadvertently steel copies from your press runs. If your actual PBW is not at or below the agreed upon PBW that you purchased, you will run short.
What does this have to do with Lean Manufacturing you may wonder? A major portion of lean is mistake-proofing the process, or Poke-Yoke if you remember an earlier edition of Lean on Print. The basis of mistake-proofing is identifying errors before they become defects. The defect in this case is a short run. The error is a high paper basis weight in one or more of your rolls. The trick is to identify this error. QTMS iQ Paper will track PBW roll by roll, letting the press operators know exactly what the actual PBW is versus the PBW stated by the mill. Used in combination with iQ Web, the lead pressman will always produce the run to required count. And purchasing can use the data to work with the mills to ensure dead-on PBW on future deliveries.
