Damaged Dies 1

[jamtilimpact]

Here's one for you: We have an injection process where we have 600+ part numbers with 1000+ dies running on 50+ presses. We had a die get damaged and we let some bad parts escape to the customer. We have instructions in place for the dies to be inspected for damage/wear at the beginning of every shift (these are very intricate parts). Still, we missed this one. The customr is demanding a preventive action- and rightfully so- but we will have to implement this plant wide and not just on this one part. Revising instructions and retraining employees has been deemed "not good enough." We have an already overtasked technician running a 3-D scanner but if we had him scan every running die every day or every few days we would a)never see the dies again and b)probably never see the 3D guy again.
Suggestions on how to satisfy the customer? We are at our wit's end.

 

[gerhardl]

Move the control to the finished parts? Sampel testing? Some modern automated photo-scanning at critical measures? In which way did the damage occur? Accidentally, wearing or what. Preventing action for cause, or deem it a one-time occurence?

 

[tygerdawg]

This works only if there is enough real estate on the part:

Permanently laser made with barcode or whatever-code to permanently identify the die. Set up a simple hierachal computer (PLC?) system at each machine that requires (1) machine recipe & (2) matching proper die number and (3) production schedule number. Dies are inspected and if damaged, then (4) are coded "BAD" for the entire plant and therefore not allowed to run at any machine until repaired and (5) coded "GOOD". Approaching the problem in this manner would require some administrative work, perhaps can somehow tie it into MRP and/or PLM systems.

Just a thought.

TygerDawg

 

[MikeHalloran]

Would this appease your customer?

{ Loudly and publicly fire the operator who ran the bad parts, and everyone who touched them on the way to the customer, and their supervisors, and _their_ supervisors. }

Probably not.

Like your customer, I'm having a hard time believing that _no_one_ noticed the screwed up parts somewhere along the way, unless the aberrant features require microscopy to detect.

Like your customer, I suspect that someone _did_ notice, and chose to say nothing about it, because of your culture. With your 600+ part numbers, 1000+ molds, 50+ machines, you're clearly a production house, and your culture is oriented toward getting _anything_ out the door.

Production workers don't choose to ship scrap. Someone at a higher station clearly does, and has been deciding to do so for long enough that the issue is no longer presented to him or her as a question, because the answer is known.

To change your culture, you have to _at_least_ identify and publicly fire that person, even if it's the President ... especially if it's the President.

Don't know who it is? Your documented malcontents do.





Mike Halloran
Pembroke Pines, FL, USA

 

[jamtilimpact]

MikeHalloran is correct in stating that the culture here is oriented toward getting parts out the door. I've been working at this plant for about a year to try and change that culture. I have to deal with a LOT of "we've been doing it this way for 20 years why change now?" Just when I think I'm making headway something like this happens. A loud and public firing has not been ruled out. It is known that someone knew of the defect because they tried to repair some of the parts but chose to keep it to themselves. To get the wolves away from the door though I am having the quality engineer begin a series of cascading A3's today beginning with 1) A quality tech will have to review the part at the beginning of each production run and approve or disapprove for running. Currently the press tech checks for defects on the initial part and a dimensional tech checks for dimensional conformance. So, basically, we're adding another layer of inspection which is really only a temporary measure. 2) A vision system will be investigated to detect gross defects on the dies. I saw these things do wonders when I worked in the automotive industry. And 3) Tygerdawg's barcode idea.
This incident has reminded me of why I got out of quality engineering: No matter whose fault it really is, it's your fault.

 

[MikeHalloran]

You're still facing in the wrong direction.




Mike Halloran
Pembroke Pines, FL, USA

 

[ajack1]

Have you considered a roving inspector?

Basically someone who just walks around and randomly inspects parts either visually or with the aid of simple fixtures, go/ nogo gauges for critical features for example.

You could also consider training operators to do this say every one hundred parts. However as has been said if someone over rules them and sends the parts out anyway you are back to square one.

 

[jamtilimpact]

Update: Customer is satisfied with the cascade of A3's that came from this. A3's are a handy little tool. Mfg is rewriting the die/part inspection process/method, training techs and operators, and are improving conditions for inspections, e.g. better lighting, magnifying mirrors to inspect while on the press, and so on. Someday we'll arrive at the point where inspections are a novelty. Now, if I only had about 5 more IE's...
Thanks to all who replied.

 

[charlie2go2ubet]

random/percentage based human inspection only works to limit the amount of mistakes that get through. To elliminate errors entirely, 100% inspection is required.

You can do this by automating the inspection process. They do this with injection molded medical parts all the time. Barcoding each part, Cognex type Visual Inspection, Air go/no-go gauges, limit switch touch gauges, laser point inspections, etc.

Elliminate the human component from the inspection as much as possible...it prevents bordom, repetitive stress, personality conflicts and man power costs. You can have the PLC do real time process control. You track number of errors, type of errors, and what parts (barcodes) are coming from which dies to watch for wear patterns, etc. automatically printing out an inspection report for each part is not much more trouble either.

Ingenious automation is the only way the US is going to stay competitive in manufacturing world wide. Work smart, not hard.