Six Sigma Case Study
Root Cause Analysis at a Direct Mail House
Mail houses take a customer's printed mailing piece and get it into the mail at the best price possible. The pieces vary in size and complexity from postcards and letters to magazines and boxes. This may involve:
- Folding the piece
- Inserting the piece into an envelope or tabbing the piece
- Preparing and de-duping one or more mailing lists
- Printing a label on each piece
- Putting postage or a bulk mail indicia on each piece
- Organizing the mail into trays for the post office
- Creating the paperwork required by the USPS
- Delivering the mail to the bulk mail post office
- And a host of related activities
Case Study Problem
One mail house encountered a disastrous error. An incorrect file was used to prepare half of a mailing. The error wasn't discovered until after the piece had been mailed.
To correct the mistake, the mail house had to pay for reprinting and all associated costs of mailing the piece with the correct file. And they had to buy another copy of the list they had mistakenly used.
The total cost of was over $5,000, which may not sound like much until you realize that they need about 15 jobs of equal size to pay for this one.
Case Study Analysis
It's not always necessary to use all of the Six Sigma Tools to resolve a problem. Whenever there's an event like this one, you can jump right into cause-effect analysis.
Most mail houses receive files electronically via email. In this case, thousands of files had built up in the attachments folder. It often took several minutes to open the folder because it was so full.
There were two with almost identical names, so the list manager picked up the wrong file. (S20021 was used instead of S20012)
Root Cause #1: Picked wrong file because of similar file names in crowded folder.
Root Cause #2: Hand written instructions on work orders
Root Cause #3: Ignoring intuition. The list manager noticed that the file only contained half the expected number of names, but didn't investigate. The production people also noticed that there were only half the names, brought it up with the supervisor, but didn't investigate. There were several opportunities to prevent the error, but no one followed up.
Case Study Solution
The goal of any solution is to prevent the problem from ever happening again. I kept asking the team members: "How can we make this fool proof, mistake proof?"
The solution was simple and elegant. Since every job is assigned a work order number. The improved process involved inserting the work order number in front of the emailed list name.
(S20012 became "WO12345 S20012"). This way all files associated with a work order would automatically be sorted together.
These files were then saved in folders labeled Jan03, Feb03, etc. so that they could be easily retrieved when the mailing was scheduled.
The mail house also realized that labeling everything with the work order number would be a good idea. So boxes and pallets of printed mail pieces began to be labeled with florescent labels showing the work order number, date received, and an expiration date (for recycling).
Root Cause #2: Instructions for each work order were typed and emailed to the list manager and production manager. Although initially considered to be slower, this process became faster and more accurate than hand written notes.
Short Term Pain for Long Term Gain
As a result of this analysis, which took about two hours and the implementation which took another couple of hours, no additional disastrous errors have occurred.
And errors overall are down. Errors in the paperwork required by the USPS are almost non-existent.
Productivity has climbed to over one million pieces per day for the first time ever.
When asked about the process, everyone agreed that the analysis was painful, but short lived. The benefits, however, are extensive and long lasting.
Sustaining the Improvement
To insure the success continues, the mail house has implemented measures of:
- Productivity (pieces/day)
- Errors (by work order)
- Rework costs (time and materials/work order)
Other Charts Included in QI Macros for Excel