Tolerance block on customer drawing - Major interpretation problem with customer

QMMike

Involved In Discussions
#1
Here is the scenerio. The tolerance block on my customer's drawing is +/- .010.
The dimension in question is .460min

What is your interpretation?
 
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GStough

Staff member
Super Moderator
#2
Re: Major interpretation problem w/ customer

How can there be a tolerance of +/- .010 when they only require a minimum? :confused:
 

Jim Wynne

Staff member
Admin
#3
Re: Major interpretation problem w/ customer

Here is the scenerio. The tolerance block on my customer's drawing is +/- .010.
The dimension in question is .460min

What is your interpretation?
Does the block tolerance have the disclaimer, "Unless otherwise noted"? If it does, there's your answer--the "min" callout supersedes the block tolerance. If not, I would still say that specifying "min" without an associated "max" leaves the door open on the high side. What is your measurement, and what does the customer say?

Once again, for those just tuning in, this is yet another example of why careful review of drawings at the quotation stage (contract review) is important.
 

RoxaneB

Super Moderator
Super Moderator
#4
Re: Major interpretation problem w/ customer

Here is the scenerio. The tolerance block on my customer's drawing is +/- .010.
The dimension in question is .460min

What is your interpretation?
What does the Customer say? I mean, we can tell you our interpretation, but in the end, isn't it about meeting the Customer's requirements? I'd love to say fix the drawing, but what does the Customer need?
 

SteelMaiden

Super Moderator
Super Moderator
#5
Re: Major interpretation problem w/ customer

I'm with Gidget. You cannot have a +/- tolerance with a minimum required dimension. I would contact the customer for clarification before accepting the order.
 

QMMike

Involved In Discussions
#6
Re: Major interpretation problem w/ customer

Does the block tolerance have the disclaimer, "Unless otherwise noted"? If it does, there's your answer--the "min" callout supersedes the block tolerance. If not, I would still say that specifying "min" without an associated "max" leaves the door open on the high side. What is your measurement, and what does the customer say?

Once again, for those just tuning in, this is yet another example of why careful review of drawings at the quotation stage (contract review) is important.
Any idea where to find a hard copy of this interpretation? My problem lies in drawing states .460 min. marked as a critical. This customer is typically "quirky" (for lack of a better term) with their drawings. Parts were made and readings reached .490-.525. All other critical dimensions were fine. Our customer received the parts, packed them into kits and then THEIR customer rejected them.....
 

Jim Wynne

Staff member
Admin
#7
Re: Major interpretation problem w/ customer

Any idea where to find a hard copy of this interpretation? My problem lies in drawing states .460 min. marked as a critical. This customer is typically "quirky" (for lack of a better term) with their drawings. Parts were made and readings reached .490-.525. All other critical dimensions were fine. Our customer received the parts, packed them into kits and then THEIR customer rejected them.....
You didn't say whether there was an "Unless otherwise specified" disclaimer. Nonetheless, you can't logically apply a bilateral tolerance to a unilateral specification. ".460 min" allows for unlimited variation above .460. Even if this were codified somewhere--and I don't know that it is--it wouldn't make any difference unless the customer had explicitly named the controlling standard (ASME Y14.5M, for example).

This is a matter of negotiation with the customer, and in order to avoid complications you might well end up having to eat the "nonconforming" parts. This doesn't mean that the customer shouldn't be put on notice that you are making a concession in order to maintain their happiness, and that the drawing (and any others like it) need to be changed.
 

Helmut Jilling

Auditor / Consultant
#8
Re: Major interpretation problem w/ customer

Here is the scenerio. The tolerance block on my customer's drawing is +/- .010.
The dimension in question is .460min

What is your interpretation?

My interpretation as an auditor is it is a conflicting dimensional statement. It is not clear. Therefore, it should have been noted during the Contract review/APQP Print review process, and resolved then. You might have had some traction to get agreement from the customer at the time.

Since you did not, there has been a glitch (almost predictable), and now you may have an issue with a customer. Now, at this juncture, you have very little traction.

Now, you still have to resolve the conflict before you move on, but you missed the opportunity to be proactive, and may have some parts to eat, as well.

This is a good real world example of why this requirement is in the standard.
 
D

D.Scott

#9
Re: Major interpretation problem w/ customer

This is a good real world example of why this requirement is in the standard.
What has been said is certainly true. We should also acknowledge that clarity is a requirement of purchasing as well. It was stated a couple of times here that there needs to be an up-front agreement and nobody can argue with that. Those of us on the purchasing side should take a lesson from this as well. We need to be clear about what we expect from a supplier.

That aside, why was the stated tolerance disregarded? Was there no thought to requirements of 0.470 +/- 0.010? The identification of a critical minimum requirement is, or certainly could be interpreted as, consistent with those requirements. I will be interested in what the customer actually thought they would get.

Dave
 

Wes Bucey

Quite Involved in Discussions
#10
Re: Major interpretation problem w/ customer

Yep. The horse [Contract Review was missing] is dead - we can stop beating it.

FYI:
Typically, my experience with job shops and contract manufacturers is that they do not take an ambiguous note or dimension as carte blanche approval to FAR EXCEED the standard tolerances for the drawing. Thus said, I would have expected most shops to have interpreted the dimension (assuming no other customer interaction during Contract Review) as 0.460 +0.020/-0.000. This means the maximum part sent to the customer would have been 0.480.
 
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