Getting Rid of Part Marking Errors

John Broomfield · Mar 22, 2020

Thank you optomist.

I’m always ready to learn the basis for the latest thinking on the effectiveness of humans inspecting outputs. Just in case someone discovers that an inspector can catch all of the nonconformities.

Juran’s handbook in 1999 gave me my stated rule of thumb.

...only he reported that Bud’s experiments showed that 100% inspection by a human was 87% effective.

The main point to our OP though is not to rely on sorting good product from bad. Get the process (and the system within which it operates) right instead.

* Measure of Inspector and Test Accuracy by Dr. Elmer F. "Bud" Gookins, Juran Quality Handbook (page 23.51) McGraw Hill, 1999. (5th Edition).

Updated to attribute Dr Gookins instead of Dr Juran

Jim Wynne · Mar 22, 2020

John Broomfield said:
Thank you optomist.

I’m always ready to learn the basis for the latest thinking on the effectiveness of humans inspecting outputs. Just in case someone discovers that an inspector can catch all of the nonconformities.

Juran in 1999 gave me my stated rule of thumb.

...only he reported that his experiments showed that 100% inspection by a human was 87% effective.

The main point to our OP though is not to rely on sorting good product from bad. Get the process (and the system within which it operates) right instead.

- Juran. 1999. Measure of Inspector and Test Accuracy - Joseph M Juran. Juran’s Quality Handbook. s.l. : McGraw Hill, 1999. (Fifth Edition).

Good, John. Now tell us about "his experiments." Details, please. Are there circumstances under which 100% inspection is not going to be effective? Of course. I think most of us know that. Are there circumstances under which 100% inspection is likely to be effective? Yes. We can't be making broad, blanket statements on a subject like this?

NDesouza · Mar 23, 2020

Mike S. said:
Yep, sounds to me like they have a system problem not a human error problem.

Is the label complex? Sometimes the labels are long and complex and having a human catch that a label is actually ASSY7762234672A-2 and not ASSY77622234672A-2 is something humans are not well suited to doing. In such cases work to eliminate human involvement as much as possible.

Than you Mike. Can you share some ideas on how to eliminate human involvement in label printing? There is only one guy keying in the label but a few others read it for accuracy and they are missing the inaccuracies on a regular basis. Which tools do you suggest?

NDesouza · Mar 23, 2020

Ron Rompen said:
Is this a barcode (2D or 1D) or is it strictly a human-readable label?

Hi Ron,
They do not make any barcode labels. They are strictly human readable labels.

John Broomfield · Mar 23, 2020

Jim Wynne said:
Good, John. Now tell us about "his experiments." Details, please. Are there circumstances under which 100% inspection is not going to be effective? Of course. I think most of us know that. Are there circumstances under which 100% inspection is likely to be effective? Yes. We can't be making broad, blanket statements on a subject like this?

Yes, it depends. And I’ve corrected my misattribution from Dr Juran to Dr Gookins.

Here is further discussion on the fallibility of a human trying to detect all the nonconformities.:

100% Visual Inspection – Being Human

John Broomfield · Mar 23, 2020

NDesouza said:
Hi Ron,
They do not make any barcode labels. They are strictly human readable labels.

Should your company specify use of a system?

Or do you have a better way of nudging your supplier to invest in reducing the costs of mislabeling?

Your supplier may find this interesting:

(broken link removed)

Miner · Mar 23, 2020

I agree with Jim. Defects that are difficult to assess and/or occur at a low PPM rate will have an effectiveness much lower than 85% while defects that are relatively easy to detect could have an effectiveness higher that 85%.

Saying 100% inspection is 85% effective all the time is like saying the river is 3 feet deep (all the time).

Ninja · Mar 23, 2020

NDesouza said:
There is only one guy keying in the label but a few others read it for accuracy and they are missing the inaccuracies on a regular basis. Which tools do you suggest?

Can you give an example of the part code we're talking about?
Is it like Mike Suggests? Other? Simpler? More complex?

We had a 4-6 digit product code and a 6-9 digit lot number for our labels.
One main person who printed the labels, with two backups in case he was out.
We made it clear to the person requesting the label that it was their responsibility that the label was right.
We made it clear to the guy printing the labels that he was to reprint labels as many times as needed to get it right.
Any complaints he had about reprints were complaints against himself.
He hated making labels, so he was very careful to not have to do it again and again.
We ran between 100-300 labels per day (many were duplicates)...often had reprints (2/week or so), rarely had any escape.

When we moved to GHS labels and needed new label software anyway...we tied it into the inventory system and avoided 99.9% of the errors (unless it was incorrect in inventory track as well).

Johnnymo62 · Mar 23, 2020

I think that spacing long callouts into a group of short segments is helpful.
ASSY7762234672A-2
ASSY 7762 2346 72A-2

NDesouza · Mar 25, 2020

Ninja said:
Can you give an example of the part code we're talking about?
Is it like Mike Suggests? Other? Simpler? More complex?

We had a 4-6 digit product code and a 6-9 digit lot number for our labels.
One main person who printed the labels, with two backups in case he was out.
We made it clear to the person requesting the label that it was their responsibility that the label was right.
We made it clear to the guy printing the labels that he was to reprint labels as many times as needed to get it right.
Any complaints he had about reprints were complaints against himself.
He hated making labels, so he was very careful to not have to do it again and again.
We ran between 100-300 labels per day (many were duplicates)...often had reprints (2/week or so), rarely had any escape.

When we moved to GHS labels and needed new label software anyway...we tied it into the inventory system and avoided 99.9% of the errors (unless it was incorrect in inventory track as well).

Hi Ninja,
the labels are looking something like this. They fit on cables both large and small. They make the labels to the customer drawing specifications and the parts vary greatly in any given day. So they guys changeover a lot and just make a new label every time they switch over.
ASSY7762234672A-2
ASSY 7762 2346 72A-2

Getting Rid of Part Marking Errors

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NDesouza

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John Broomfield

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Miner

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Ninja

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Johnnymo62

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NDesouza

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