Visual Inspection Not 100% Effective - How to Improve Visual Inspection

J

jkittle

Does anyone have any ideas on how to improve visual inspection sorts?

I have a customer who expects zero defects (like us all I'm sure) especially when comes to sorting. We have had times when we have had to do a 100% visual sort for a defect that has not been 100% effective and still sent defects to the customer. I don't know what else we can do. We take the product to an offline location and have a very detailed process flow, visual identification, rework instructions, signed acknowledgement that the full time employee understands the sort and QA does a final sample inspection (random sampling) to see if any defects are found.

I contend that visual inspection can never be 100% effective 100% of the time. My customer does not accept that. I have tried disqualifying people to sort if the customer finds defects in their material, that didn't work now I have a plant full of people who can't sort. I have had QA go back through the material 100% and they have made mistakes.

What else can I do? The customer says, what are you going to do different next time? I don't know!!!!!
 

Jim Wynne

Leader
Admin
Re: Visual Inspection Not 100% Effective

Does anyone have any ideas on how to improve visual inspection sorts?

I have a customer who expects zero defects (like us all I'm sure) especially when comes to sorting. We have had times when we have had to do a 100% visual sort for a defect that has not been 100% effective and still sent defects to the customer. I don't know what else we can do. We take the product to an offline location and have a very detailed process flow, visual identification, rework instructions, signed acknowledgement that the full time employee understands the sort and QA does a final sample inspection (random sampling) to see if any defects are found.

I contend that visual inspection can never be 100% effective 100% of the time. My customer does not accept that. I have tried disqualifying people to sort if the customer finds defects in their material, that didn't work now I have a plant full of people who can't sort. I have had QA go back through the material 100% and they have made mistakes.

What else can I do? The customer says, what are you going to do different next time? I don't know!!!!!

It's very possible that you are doing everything you can with regard to the sorting, and anything else you might try will be futile. It looks to me like what you need to do is make a conscientious effort to eliminate the need for sorting by preventing the defects from occurring in the first place. Your customer might be placated by telling them that you're doing the best you can with the sorting, but you want to expend the extra effort on prevention.
 

Marc

Fully vaccinated are you?
Leader
Re: Visual Inspection Not 100% Effective

I think the key here is to let us know what the defect is you're trying to identify.
 

BradM

Leader
Admin
Re: Visual Inspection Not 100% Effective

In my opinion, your contention is correct. I would have to do some research, but I think the best you could probably expect is around 90%. If you add inspectors, your accuracy decreases due to Social Loafing issues (the other guy will catch it mentality).

It's possible to make process improvements, operator inspections, SPC, etc. to decrease defects.
 

ScottK

Not out of the crisis
Leader
Super Moderator
Oh boy have I walked in those shoes and it's been the most frustrating thing in my whole career.

It's probably no help right now but this has to go back to the contract review.
Whoever accepted a contract for zero defects obviously didn't review it with anyone who knows the process.

I suggest you put all of this on paper, submit the expense of the sorting and re-sorting and re-re-sorting to people up the financial chain and tell them that they should either renegotiate the contract or start spending some money on prevention.

...unless this job is marked up so much that 500% inspection is worth it.
 
J

jkittle

The most recent was caused by our customer. They did not send us our returnable packaging and sent us a substitute in lieu. The packaging caused damage to a small amount of the parts because it was the incorrect packaging (this was also brought to the customer’s attention before shipment). So we had to place remaining product on hold and sort and repack (when they finally sent the correct packaging).

So the root cause of this particular defect is my customer, but they insist that the two are separate incidents. The first 16 defects caused by the packaging and the next 8 by an ineffective sort which is our fault.
 

atitheya

Quite Involved in Discussions
Try using a detailed specification cum checklist for visual inspection for each item/product. (If you are not already using one)

This will give in detail what needs to be checked and also wether everything was specifically checked, and, a record of each item being checked in case you need to refer who checked what and when while tracing backward for a defective piece identified later.

There could be seperate checklist for each product or even a matrix checklist for multiple products in one checklist.
 
D

D.Scott

:2cents:

Sorry, but I don't agree with the 100% premise. If you were sent into a room with 10 refrigerators and told to pick out the red ones, I'm betting you would be at 100% or you are possibly blind.

The point is, Jim has pointed out you may need to prevent the defect in the process so you won't have to sort. Great idea and a firm winner. Marc has asked what you are sorting for which gets back to the refrigerators. To know how to help we need to know the problem.

If you do have a product defect where you can only be 85% effective on 100% inspections, sort them 3 times and the defects you miss should be so small the customer might be satisfied.

I go along with Jim. Work on eliminating the cause of the defect. Continue your 100% sort (3 times if needed), collect the data on what the defect is, Pareto the results and determine where in the process the defect could occur. Use 5-ups to come up with some ideas on how to eliminate the possible defect makers. I would involve the customer as much as possible for two reasons. First, to show you are working for a solution. Second to head off any process change problems you may encounter.

If all else fails, go into the red refrigerator business. Good luck :)

Dave
 
R

ralphsulser

There are some electronic vision inspection systems now available that will 100% parts, and automatically kick out those that do not conform to the master standard. I do not have detail knowledge of the systems and cost, but have seen them in action at an automotive assembly plant.
If you can't go back upstream to prevent the defect, then this may be a method to sort without the inspector fatigue.
Also, we were taught by ASQ(C) a long time ago that 100% inspection is only "75% effective at best".
 
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