Final Inspections - Does 100% inspection really work

[Jason I]

My company is a custom fabricator (plastics), we perform a 100% final inpection, yet we still deliver defects to our customers.

Do 100% inspection really work if not what suggestions can you offer?

[JRKH]

Jason,

There is a pretty good thread on this very subject at:

http://Elsmar.com/Forums/showthread.php?t=3835

There are so many factors it is hard to know where to start.

Have you analyzed the returned parts for possible trends?
How many inspectors are assigned to final inspection? (single or double inspection)
Are more bad parts missed on a certain day? (TGIF syndrome)
Is your measurement system up to par? (Maybe run an MSA)
How complex are the parts?
How many breaks do the inspectors get? (fatique)

These questions are off the top of my head. I am sure others here will have more.

Maybe you could let us know what you have done so far to find the cause.

James

[Michael T]

Originally posted by Jason I
My company is a custom fabricator (plastics), we perform a 100% final inpection, yet we still deliver defects to our customers.

Do 100% inspection really work if not what suggestions can you offer?

Hi Jason - welcome to the Cove.

I think you may have answered your own question... if you are conducting 100% inspections and still deliverying defects - the answer is "No". Not with your current process.

There is a great discussion under the following that talks about inspections and probabilities of catching defects:

General Quality Topics > Quality Gurus, Philosophy and Evolution > 100% Inspection - 80% Accurate - Quote from Juran (?)

Can 100% inspection catch 100% of the defects of a process? Nope - not with humans doing the inspection. With machines? Nope - not with machines either... it gets better (depending on the item being inspected) but it is still fallable.

My suggestion is pretty simplistic. Conduct an analysis on the types of defects you are getting. Once you've figured those out, do a root cause analysis on your most significant 20% (80/20 rule). Once you've done the root cause analysis that defines the subprocess(s) that are causing the defect(s) - fix them. Then check your results. If you are still getting defects, do it again. PDCA cycle in action.

Good luck!!!

[gpainter]

Not sure what industry you make plastic parts for. I know from past experience that many automotive customers require 100% final inspection. Some of it was not what I would call a final inspection. Remember this adds cost to the customer and to your company in more ways than one. You can 100% inspect 5 times and still send bad parts. Concentrate on building quality into the product and process capability to reduce all inspections to add value to the customer and improve your competitive advantage.

[M Greenaway]

As stated in other posts.

Dont accept the fact that your process makes defective items and expect your inspection to weed out the bad parts.

Use the data gleaned from your inspection activity to eliminate the causes of your problems.

As you have realised for yourself 100% inspection does not assure defect free products are delivered to your customers.

Its notable that some aerospace component manufacturers perform 8 times 100% inspection, which clearly indicates the effectiveness of a single 100% inspection.

[Marc]

I received this from Jason I -- I think the 'wrong' link was pressed on the notification e-mail and he sent it to me instead of replying to the thread:
*********************
I was maybe a little vague in the description of our business (customs displays), we are very, very labour intensive, our production runs are short (never repeated), and product appearance is paramount. Finally up to 25 projects can be on the shop floor at the same time and each carries it's own inspector.

Our quality program is very young, however based on data collected (inpections, CAR, Customer complaints) to-date workmanship appears to be the #1 cause of rejects. We have started some OTJ training for all supervisors, to follow later with training for all workers.

My concern still, workmanship is a human factor and all my resources and readings have indicated that I should be checking my processes not looking at the human factor, does this then mean that our processes are flawed. The company has been around for over two decades.