FIRST PIECE PASSED WHEN IT SHOULDNT HAVE

[Mike S.]

Yes, root cause has to address why you made the screw wrong in the first place.

Detection failure is a contributing cause.

 

[Randy]

Here we go again Rube-Goldberg-Solutions to simple problem being presented (using a napkin)

 

[greatwhitebuffalo]

We are a high mix job shop and as such we do two FAI's per setup. The operator runs the first piece and performs the inspection, then submits it to the QC inspector and they perform an inspection, if the 2 jive then production starts. Has saved us from silly mistakes more than once.

 

[Bev D]

You have been given some really good advice:
First ask your inspectors how they missed the ’defect’: in my experience, using the words ‘how did this happen’ or ’what happened’ creates a less hostile environment to get the inspectors to provide useful information. Don’t just assume that they are lazy or incompetent or stupid or whatever…there may be a very good reason…there might not but your job is to determine the truth not confirm anyone’s bias about what happened.
Second you need to understand how the wrong part was made in the first place.
BOTH of these things are important…

 

[Johnny Quality]

This isn't too swift either.... Answer "Because we want some half threaded and some full threaded" (DUH)

What if after reviewing the designs they are not needed?

 

[ChrisM]

The issue arose because of a mistake (accidental or deliberate) at manufacturing and then at first article inspection. How did it happen? Review the inspection practice - does the inspector mark the drawing for each feature that is checked? Does he/she use a different drawing to inspect to, compared to the drawing the machinist used or was inspection passed the same drawing to use? Did the inspector verify he/she checked using the correct drawing and revision/issue level as required by the Work Order? Once you know the answers to these questions, you can start to investigate (with a team) and put appropriate steps in place (which may be as simple as just reminding inspectors to take nothing for granted and measure from scratch each time, checking drawing/work requirements align)

 

[Sebastian]

INSPECTION aspect is not important for me.
I am always interested in HOW IT WAS MADE?

First piece has to be OK with probability of 99,99%
There was something wrong with definition of setup activities and following it verification.
It should be OK at this stage.
As it wasn't, so first piece was made wrongly and inspection has potential to be ineffective.

Don't make NOK parts, you won't worry about inspection efficiency.

 

[Bev D]

Because you don't need dimensional anything to tell threaded from non-threaded to start with.

I do think that this is a valid question for us to ask as the OP provides little information for us to work with. Certainly we’ve seen many posts where the OP comes here looking for permission to discipline an operator or inspector for ‘screwing’ up (pun intended) and they withhold (deliberately or not) critical information that would get us and them at the true cause…and most of us have experienced this very thing in our own work.

It would be a valid question for the Quality Manager to ask if they haven’t yet done so. The missed visuals could be just the tip of the iceberg of what is wrong here. The OP has stated that they are a new QM and they don’t even know where to start to fix the issue…The OP really does need to understand the system they are working in. If the machinist and the inspectors all missed the visual then it makes sense to ask about the other dimensions. There should be several dimensions to check in a first article for a screw. If not, why not? If so, are they correct? If the obvious visual was missed were the dimensions requiring measurement also missed? (That would be a BIG hole in the system) And usually the threaded part would be a dimension on the print…not simply a visual check that some undefined area is not threaded.

Too frequently a seemingly simple event of missing a visual criteria is just a symptom of a greater problem. An important part of a Quality manager or engineer’s job is to be able to think critically and deeply about the system. As a profession we suffer from shallow ‘cut and paste’ thinking and mere compliance to some standard that isn’t even read, let alone understood. If it is unacceptable for the inspectors to have "don't give a "S"-itis", then it is doubly unacceptable for the the QM to have "don't give a "S"-itis"…