SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in place?

Jim Wynne

Staff member
Admin
#31
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

Yes, mostly American manufacturers imho. If you have to "get use" to 100% inspection as a norm, again, imho, you should not be in that particular commodity in the first place. I am 100% American, born and raised in Michigan actually. "Getting use to"...100% inspection tells me about an organization's top management support. A cop out imho. Also, "vs" imho does mean one or the other. Of course all of us Quality professionals would never dream (or would hope not) only utilizing only one or the other Quality problem solving tool for any given scenario. My extensive travels have showed me one thing, among many, I would never hear such a thing in some other countries, meaning SPC vs. 100% inspection...all catching up with us now.
Once again, the OP said he's already doing 100% inspection, and wanted to know if it would be useful to do SPC in addition to it, not in place of it. Unfortunately I'm not in a position of omniscience and can't see the OP's process and can't offer an opinion as to whether the 100% inspection he's doing is needed or not. There are times--all over the world and in many types of businesses--when 100% inspection is necessary and can't be responsibly done away with and this is despite mindless platitudes about 100% inspection being evil in every case.
 
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bobdoering

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#32
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

Yes, mostly American manufacturers imho. If you have to "get use" to 100% inspection as a norm, again, imho, you should not be in that particular commodity in the first place. I am 100% American, born and raised in Michigan actually. "Getting use to"...100% inspection tells me about an organization's top management support. A cop out imho... I would never hear such a thing in some other countries, meaning SPC vs. 100% inspection...all catching up with us now.
I guess you missed the point about SPC not capable of ensuring 100% good product, didn't you? I guess "other countries" must be able to tolerate a quality level worse than 0 defects to never perform 100% inspection, or your experience is still too limited to have come across those industries that demand 0 defects elsewhere in the world. I know our suppliers from elsewhere in the world do 100% inspection, so I think your sampling holds some error...as sampling tends to do.

"Getting use to"...100% inspection has no relationship to lack of an organization's top management support. It has to do with the recognition that any sampling methodology can not assure 0 defects, and the organization is willing to protect their customer from defects. It can also be a fail-safe redundancy. With international shipments, it is generally cheaper to ensure with absolute certainty that parts leaving the firm are good before starting their journey on a boat. In that respect, it shows a significant top management support, willing to spend the time and effort to ensure quality product to their customer.

There may be things that are "catching up with us now", but 100% inspection is not it.
 
B

brahmaiah

#33
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

I guess you missed the point about SPC not capable of ensuring 100% good product, didn't you? I guess "other countries" must be able to tolerate a quality level worse than 0 defects to never perform 100% inspection, or your experience is still too limited to have come across those industries that demand 0 defects elsewhere in the world. I know our suppliers from elsewhere in the world do 100% inspection, so I think your sampling holds some error...as sampling tends to do.

"Getting use to"...100% inspection has no relationship to lack of an organization's top management support. It has to do with the recognition that any sampling methodology can not assure 0 defects, and the organization is willing to protect their customer from defects. It can also be a fail-safe redundancy. With international shipments, it is generally cheaper to ensure with absolute certainty that parts leaving the firm are good before starting their journey on a boat. In that respect, it shows a significant top management support, willing to spend the time and effort to ensure quality product to their customer.

There may be things that are "catching up with us now", but 100% inspection is not it.
Yes, SPC doesnot guarantee 0-defect.But 100% inspection also doesnot guaratee 0-defect unless it is a computer controlled 100% inspection.But when we say 100% inspection we generally mean manual 100% inspection.
The emphasis should be on a perfect process rather than on a perfect inspection.
V.J.Brahmaiah
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#34
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

Yes, SPC does not guarantee 0-defect.But 100% inspection also does not guarantee 0-defect unless it is a computer controlled 100% inspection. But when we say 100% inspection we generally mean manual 100% inspection.
The emphasis should be on a perfect process rather than on a perfect inspection.
We do not know whether the OP meant 100% visual or mechanical inspection. As far as his original question was concerned, it was irrelevant which it may be. Even this discussion is beyond the original question, which was already conclusively answered. We are really discussing the converse of the OP's question at this point, for its own academic merit, I suppose.

I agree, the holy grail is the perfect process, with the perfect raw materials, and the perfectly timed preventive maintenance, and so forth. But, until such time that one achieves this, one is compelled to employ necessary means to protect the customer. And, for all of the tools needed to reach the holy grail of perfect process, SPC alone is not enough. It has its place, when properly implemented (emphasized on purpose!) - and even that is a rarity.
 

mbehmazia

Involved In Discussions
#35
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

I guess you missed the point about SPC not capable of ensuring 100% good product, didn't you? I guess "other countries" must be able to tolerate a quality level worse than 0 defects to never perform 100% inspection, or your experience is still too limited to have come across those industries that demand 0 defects elsewhere in the world. I know our suppliers from elsewhere in the world do 100% inspection, so I think your sampling holds some error...as sampling tends to do.

"Getting use to"...100% inspection has no relationship to lack of an organization's top management support. It has to do with the recognition that any sampling methodology can not assure 0 defects, and the organization is willing to protect their customer from defects. It can also be a fail-safe redundancy. With international shipments, it is generally cheaper to ensure with absolute certainty that parts leaving the firm are good before starting their journey on a boat. In that respect, it shows a significant top management support, willing to spend the time and effort to ensure quality product to their customer.

There may be things that are "catching up with us now", but 100% inspection is not it.
If you ever want to find out the level of top management commitment, just observe what's being sent out the door. 100% inspection does not guarantee 100% good product either. I have seen this scenario play itself out far too many times. Regarding "fail-safe redundancy", hmmmm, fail safe? Redundancy? Couldn't have said it better myself. Let's keep investing in non-value added processes. Hip-hip- hoorah!
 
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bobdoering

Stop X-bar/R Madness!!
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#36
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

Regarding "fail-safe redundancy", hmmmm, fail safe? Redundancy? Couldn't have said it better myself. Let's keep investing in non-value added processes. Hip-hip- hoorah!
If your preference is providing work for overseas sorting companies rather than catching issues closer to the process, then cheers to you! :rolleyes:
 

mbehmazia

Involved In Discussions
#37
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

Imho, it is impossible to 100% inspect Quality into a part or process-'nuff said.
 

Jen Kirley

Quality and Auditing Expert
Staff member
Admin
#38
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

Let's summarize.

SPC and inspection are not the same, even if the sample for SPC is getting the same exact examination/testing as the parts being 100% inspected. That's because SPC is about reducing defects in a process and inspection is about reducing (hopefully eliminating) defects going out the door.

For that reason, SPC can be worthwhile even if 100% inspection is performed, since SPC is supposed to be done for the purpose of reducing defects that result in scrap, or may get to the customer in any case; for various reasons even computer aided inspection isn't infallible.

Risk, regulation and economics are factors to determine what processes (SPC, full inspection or both) are to be used, toward what goal(s), and so on.
 

Jim Wynne

Staff member
Admin
#39
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

Imho, it is impossible to 100% inspect Quality into a part or process-'nuff said.
I don't think that anyone believes that 100% inspection is a panacea, or that it will always detect 100% of the defectives. To that extent, you're arguing against a strawman. Sampling is always better when sampling obviates 100% inspection. We know this. But saying that sampling is always better is like saying that it's better for everyone to walk to work rather than driving. A rational decision to do 100% inspection in no way indicates that responsibility for efficacious process design has been abdicated. It means that after all possibilities, risks and costs have been considered, 100% inspection is the responsible thing to do.
 
V

Vicman

#40
Re: SPC vs. 100% Inspection - Is SPC still value-added when 100% inspection is in pla

Here are my 2 cents contribution.Please take a look at my attachment that shows an example I put together.




Vicman

“Quality is a matter of mentality, not nationality”
 

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