Greetings all,
I have a problem relating to the manufacture of a very KEY part in a tank assembly we are putting together for a customer.
I ask your pardon in advance for this long winded explanation of the problem:
( Manufacturer names omitted to protect the guilty)

Manufacturer A puts out a product (supplied by manufacturer C) touted in sales literature as having an accuracy of 0.05%. We order this product and on receipt of said product test it. Results are a staggering full 2%. While this may seem to some a small difference, I assure you 200Lb per 10,000 can be quite detrimental to some processes.
We call Manufacturer A to express our dismay. They have us send the product back to their supplier (C) for evaluation. Well, C says its OK-All good-NO Problem Found by their view, and send items back to us without any calibration or testing data at all. :mad:

Now by this point we have custom hardware made to fit the specifications of Manufacturer A product which we feel we can not use as it doesn’t come near specifications.

We now have to go to Manufacturer B for a similar product (at an increased cost to us) touting similar accuracy.
We also have to scrap custom made parts and have them reworked to accommodate the engineering by customer to Manufacturer A product specifications. (we absorb the cost of this as our word is good)

Parts come in from B and are tested. You guessed it. SAME PROBLEM FOUND.
This is no wonder as they are supplied :jawdrop:by manufacturer C. The problem is not as pronounced as C uses a different set up process for A and for B. No sense sending it back to C given the results of product A’s evaluation.:mad: :mad:
( we believe we have found the cause of the defect in both products but no one is willing to accept and fix the cause as it would take serious money to do)

Now here is the kicker---- I send items out directly to C on a regular basis for remanufacture. Makes me want to question that facet of their business too.

It gets better: A has a history of ignoring any request for corrective action. I have issued several this year alone, all to no avail. (unfortunately, they have other products that serve a purpose in our market and we can not find a reasonable alternative even though I have had trouble with them too.)

B is 9001 registered and is always cooperative with any request I make. One of the items from this order had to be sent back because it was not assembled properly. They replaced it overnight with relatively no questions asked.

Now, before I open this huge can of worms, involving 3 of my suppliers, ( lets face it, there are only so many people that do what they do and I don’t want them to cut ME off for being a pain in the A**) I thought I would ask the wealth of sage advice contained in the cove.

I believe I have already decided on a course of action but I would so appreciate your suggestions on how to get all 3 to cooperate in correcting the problem.

As an aside: If we did not have the ability to test up to 60,000Lb we would never have found this fundamental defect. It also shows us as a company you can never just trust what walks in the door. Examination is the key to our business. The system works.

Oh….and the whole system was scraped and reengineered using another method.
We lost a lot of money but we keep our reputation for honesty and quality.

Thank you for any advice you have

Greetings all,
I have a problem relating to the manufacture of a very KEY part in a tank assembly we are putting together for a customer.
I ask your pardon in advance for this long winded explanation of the problem:
( Manufacturer names omitted to protect the guilty)

Manufacturer A puts out a product (supplied by manufacturer C) touted in sales literature as having an accuracy of 0.05%. We order this product and on receipt of said product test it. Results are a staggering full 2%. While this may seem to some a small difference, I assure you 200Lb per 10,000 can be quite detrimental to some processes.
We call Manufacturer A to express our dismay. They have us send the product back to their supplier (C) for evaluation. Well, C says its OK-All good-NO Problem Found by their view, and send items back to us without any calibration or testing data at all. :mad:

Now by this point we have custom hardware made to fit the specifications of Manufacturer A product which we feel we can not use as it doesn’t come near specifications.

We now have to go to Manufacturer B for a similar product (at an increased cost to us) touting similar accuracy.
We also have to scrap custom made parts and have them reworked to accommodate the engineering by customer to Manufacturer A product specifications. (we absorb the cost of this as our word is good)

Parts come in from B and are tested. You guessed it. SAME PROBLEM FOUND.
This is no wonder as they are supplied :jawdrop:by manufacturer C. The problem is not as pronounced as C uses a different set up process for A and for B. No sense sending it back to C given the results of product A’s evaluation.:mad: :mad:
( we believe we have found the cause of the defect in both products but no one is willing to accept and fix the cause as it would take serious money to do)

Now here is the kicker---- I send items out directly to C on a regular basis for remanufacture. Makes me want to question that facet of their business too.

It gets better: A has a history of ignoring any request for corrective action. I have issued several this year alone, all to no avail. (unfortunately, they have other products that serve a purpose in our market and we can not find a reasonable alternative even though I have had trouble with them too.)

B is 9001 registered and is always cooperative with any request I make. One of the items from this order had to be sent back because it was not assembled properly. They replaced it overnight with relatively no questions asked.

Now, before I open this huge can of worms, involving 3 of my suppliers, ( lets face it, there are only so many people that do what they do and I don’t want them to cut ME off for being a pain in the A**) I thought I would ask the wealth of sage advice contained in the cove.

I believe I have already decided on a course of action but I would so appreciate your suggestions on how to get all 3 to cooperate in correcting the problem.

As an aside: If we did not have the ability to test up to 60,000Lb we would never have found this fundamental defect. It also shows us as a company you can never just trust what walks in the door. Examination is the key to our business. The system works.

Oh….and the whole system was scraped and reengineered using another method.
We lost a lot of money but we keep our reputation for honesty and quality.

Thank you for any advice you have I was under the impression you worked for a calibration lab.

Is it your contention weighing devices provided by supplier are off by 200# in 10,000# versus expected 5# in 10,000#?

If so, I can see where some chemical mixing processes where component chemicals are measured in process would or could result in highly uneven end product (consider pigment in paint or garlic in spaghetti sauce!)

Obviously, you need to get the attention of top executives at your company and ALL suppliers to emphasize the seriousness of the problem for your application if your evaluation of the nonconformance is correct.

Once parties agree on seriousness of issue, you can work together to confirm or deny your finding. If confirmed, then work on a solution. If not confirmed, . . .

I can't add much to Wes's advice, but it seems to me that the sort of tolerance you're referring to is usually tied to a range or limit of capacity of some sort, above (or below) which all bets are off. I know that hindsight is 20-20, but if I were told that the accuracy was .05%, I would ask "Across what range?" before signing anything.

Thanks Wes,

Yes, I do work for a calibration lab.
We also provide service, repair and product for various applications from analytical balances to Rail Road Scales, high speed applications, batching, etc.
Our scope is therefore up to 200,000Lbs.
We are distributors/ factory reps. for various brands of weighing equipment.
We do not supply the vessels, only the weighing mechanics of a project.
Our resident applications engineer is most excellent in his field.

You are correct in your assessment of the problem.

I fear I have an up hill battle getting C to understand they have to buy the tools they need in order to manufacture this particular (and maybe others I don’t know) product.

Jim, I just saw your post.
answer is @30,000Lb. according to written specifications confirmed with manufacturer.
error expands continually after 10,000Lb.

Thanks Wes,

Yes, I do work for a calibration lab.
We also provide service, repair and product for various applications from analytical balances to Rail Road Scales, high speed applications, batching, etc.
Our scope is therefore up to 200,000Lbs.
We are distributors/ factory reps. for various brands of weighing equipment.
We do not supply the vessels, only the weighing mechanics of a project.
Our resident applications engineer is most excellent in his field.

You are correct in your assessment of the problem.

I fear I have an up hill battle getting C to understand they have to buy the tools they need in order to manufacture this particular (and maybe others I don’t know) product.

Jim, I just saw your post.
answer is @30,000Lb. according to written specifications confirmed with manufacturer.
error expands continually after 10,000Lb.
I suspect we are dealing with transducers which send a variable electric current as a metal membrane containing a wheatstone bridge is deformed. The current drives a gage giving a weight reading.
What appears to be happening is deformation beyond the elastic limit of the specific metal membrane.

This is why various transducer operated scales have different weight ranges and greater or lesser discrimination within those ranges. (the difference between a pharmacy lab digital scale that reads in micrograms and a railroad scale that reads in 100 pound increments) I don't know enough about the practical application - if my surmise is correct, what would the solution be?

I fear I have an up hill battle getting C to understand they have to buy the tools they need in order to manufacture this particular (and maybe others I don’t know) product.

Is the problem that the scale doesn't read enough digits, or that the digits that are displayed are incorrect?

Assuming the later, would it be possible to recalibrate the instruments yourself (since you seem to be a calibration lab and better equipt to do this yourself than the manufacturese are :frust:)? Perhaps just adjusting a trim pot somewhere will bring the scales back into calibration? Or even just a conversion table that tells you that a reading of 20,000 lb really means 20,130 lb. Granted either of these are extra work, but it might be cheaper for you and the supplier - perhaps negitiotiate a price reduction for not meeting the specs they quoted. Or perhaps you could start offering this calibration service to them so that their scales really do match their claims. :lol:

Jim, I just saw your post.
answer is @30,000Lb. according to written specifications confirmed with manufacturer.
error expands continually after 10,000Lb.Being a little cynical, is the 0.05% specification at 30,000 lb, or anything up to 30,000 lb? I could imagine adjusting the scale to read properly at 1 specific value, but not being linear so the reading gets progressively farther off either above or below this value. Perhaps by the time it is down to 20,000 lbs, it is off by 2%.

Tim F

Thanks to you all,
I do appreciate your interest in what we do.

Wes, we believe the defect is in the grind of the spherical washers contained in the cell.
They fit kind of like a contact lens. If the grind is off it caused distortions. No amount of recalibration will correct this. On testing, ascending is bad, and descending is atrocious.
Put 4 of these on a tank and the errors go from the sublime to the ridiculous.
This is even worse because the customer wanted to also batch out product.

The long and short of it is we have found a work around that will satisfy the customer’s needs.

The question still remains as to the issue of suppliers that either refuse to acknowledge a problem and/or refuse to acknowledge their own supplier problem (A). I am confident B will at the very least investigate the evidence I will provide them including our data and that supplied by C after pulling teeth to get. The statement (verbally) I got form C was it was only a couple of hundred pounds.:mad: I do intend to go as close to the top of all three companies as I can get.:mad:
And what about C? I use these people for many rebuilds. While we have had issues with them in the past ( no one is perfect all the time especially us) they have corrected them in a timely fashion.
Just not using them is not an option.

Well, thanks for letting me vent!

Update on our dilemma.

Well, as I presumed, manufacturer A has basically washed their hands of the issue.:mad:
Also as I presumed, manufacturer B has sent a rep to us to personally take one of the load cells to a third party for retesting, as manufacturer C said there was something wrong with our equipment and or methods. This third party (yes, a competitor) has the only other machine capable of performing the same tests to the same capacities in our area.
Lo and Behold, the errors are the same as we found.:applause:
As far as I am concerned, this only serves to show the competency and diligence of our technicians in examining new equipment “according to our procedures” :notme:
Manufacturer B will now continue the quest along with us.

Now the real fun begins……

I will let you know what happens, if you are interested.

Update on our dilemma.

. . . . . .
Now the real fun begins……

I will let you know what happens, if you are interested.Interested? Heck, I'm fascinated! By all means, let us hear "the rest of the story"