Thickness not exceeding 2?0.3 mm - Value1 < value2?Value3

L

Libnani

#1
Thickness not exceeding 2±0.3 mm - Value1 < value2±Value3

We have a customer which asks in his tender specification for a product which must have a thickness not exceeding 2±0.3 mm .

what should we offer in this case ?
is it acceptable that i will offer him a product with a thickness of 1.7 mm ?:confused:
 
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G

gereard_kgb

#2
Re: Value1 < value2±Value3

well, it seams the thickness of the product should be in the range 1,7 - 2,3mm.
any thickness in this range is OK.

I would prepare something in the middle just to be in the safe side...
yet if you materials are expensive and you can cut on the costs 1,75mm would be economically justified, IMHO.

:2cents:
 
#3
Re: Value1 < value2±Value3

Aiming for 1.7mm is not a good idea, as it is right on the tolerance limit.
yet if you materials are expensive and you can cut on the costs 1,75mm would be economically justified, IMHO.
You also need to know the thickness variation to play that game. The example given would work if it stays within +/- 0.05mm.

Also worth noting: 2±0.3 mm is a pretty wide tolerance but it may still be that the part works less well close to a tolerance limit, than close to the nominal thickness 2.00mm.

/Claes
 
L

Libnani

#4
Re: Thickness not exceeding 2±0.3 mm - Value1 < value2±Value3

If I reformulate the equation , i have

thickness < [1.7 mm - 2.3 mm] then a value of 1.7 mm and more will be inacceptable ,
I should take a value < 1.6 mm , non ?
 
B

Bill Ryan - 2007

#5
Re: Thickness not exceeding 2±0.3 mm - Value1 < value2±Value3

If I reformulate the equation , i have

thickness < [1.7 mm - 2.3 mm] then a value of 1.7 mm and more will be inacceptable ,
I should take a value < 1.6 mm , non ?
My feeling is that you have "reformulated" the equation incorrectly. I read the "not to exceed" requirement as needing to be 1.7/2.3 mm.

I agree with gereard and Claus that, without knowing the product and the variability of the manufacturing process, you should probably be targeting 2.0 mm. As with most replies to these types of questions, the safest bet is to ask the customer for clarification. We can theorize all we want at the Cove (and we normally come up with very good "theories":rolleyes:) but the customer has the correct answer.
 
G

gereard_kgb

#6
Re: Thickness not exceeding 2±0.3 mm - Value1 < value2±Value3

Taking the formula formally that should be true.
It seams the thickness of the material (taking into account only the requirements of the client) should be below this range. Depending on their understanding of the brackets the max thickness can be 1,6 if they condider the [-brackets to be 'open' - 1,6(9) to be very precise - anything below 1,7, or 1,7 if they find [-brackets to mean 'closed' range.

Any way, I would definitely contact them to check what do they mean exactly. What is the point in asking the thickness to be below some range instead of saying that it should be below some given thickness (here being 1,7mm).

Of course, technological issues need to be taken into account... :)
 

Tim Folkerts

Super Moderator
#7
Re: Thickness not exceeding 2±0.3 mm - Value1 < value2±Value3

My feeling is that you have "reformulated" the equation incorrectly. I read the "not to exceed" requirement as needing to be 1.7/2.3 mm....
I expect the customer meant "to fall within the range of 2.0 +/- 0.3", which is what the answers above seem to assume as well. The literal interpretation of "not to exceed 2.0 +/- 0.3" is that zero thickness would be OK, since it does not exceed the specs.
As with most replies to these types of questions, the safest bet is to ask the customer for clarification. We can theorize all we want at the Cove (and we normally come up with very good "theories":rolleyes:) ...
This may be a case of poor translation from one language to another, or just a poorly worded spec. Bill hit the nail on ther head - double-check with the customer.

... but the customer has the correct answer.
I've certainly known customers to be clueless about what they really want. :lol:

Tim F
 
L

Libnani

#8
Re: Thickness not exceeding 2±0.3 mm - Value1 < value2±Value3

the communication with this customer is not so easy ,
He requires that we follow the specification 100% (it seems that his
specification is a national standard and he cannot modify any word of it !)

then i am faced with a mute non understandable specification !
My decision is to offer my thickness in my datasheet in the format :
thickness = 2±0.3 mm
and i produce my product with a thickness 2±0.2 mm .

what do you think ?
 
G

gereard_kgb

#9
Re: Thickness not exceeding 2±0.3 mm - Value1 < value2±Value3

this seams reasonable but what if they've meant something else?

what is the country of origin of your client? perhaps you could find some co-national of your clients who could give you a hand with this issue and walk around the issue of translations...

:cool:

good luck any way!
 
#10
Re: Thickness not exceeding 2±0.3 mm - Value1 < value2±Value3

He requires that we follow the specification 100% (it seems that his specification is a national standard and he cannot modify any word of it !) ?
Oh, I do not think there is any need to modify the customers specification, but it is easier to get to grips with the customers needs if you know how the product will be used.

My decision is to offer my thickness in my datasheet in the format :
thickness = 2±0.3 mm
and i produce my product with a thickness 2±0.2 mm .

what do you think ?
If the requirement is 2±0.3 mm and you can stay within 2±0.2 mm, you should have no problems.

/Claes
 
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