Help! Can't find English term for GD&T concept.

[supergee]

Hello All,

I am pulling my hair right now trying to find documentation on a concept for which I do not know the English term. As you can guess, English is not my first, nor my second language. In French, the term is "transfert de cotes géométrique" which litterally translate to geometrical dimensions transfering.
I tried searching the web and can't find any document on the subject.

I will summerize the topic here hoping someone will understand and give me the English term for that concept and if possible a reliable source so I can learn more on the subject.

This concept is the one where one converts a dimension from one Datum face to an other face. It is used by methods engineering in order to have dimensions from a more pratical Datum for manufacturing puposes and still respect the original design tolerances. Ususally, this process makes the new tolerance tighter than needed but that aspect might be compensated by the fact that the part doesn't need to have multiple jigs to be manufactured.

here is a link about this subject in French. hopefully, the drawing will help understand the subject [URL unfurl="true"]https://analyse-fabrication.univ-lille.fr/co/ch4_1_2.html#:~:text=transfert%20de%20cotes%20%C2%BB.-,D%C3%A9finition,cotes%20utiles%20%C3%A0%20la%20fabrication[/url]

Thank you all for your help.

 

[AndrewTT]

At my company we have the part drawing and sometimes there is an accompanying drawing that we call the "process print". The process print can have different dimensions/notes than the part print. The process print dimensions/notes are based around measurements that can be taken quickly (calipers, micrometers, etc.) at the location where the part is being made (press, lathe, mill, grinding station, etc.). It is understood that the final inspection of the parts is always to the part drawing.

 

[3DDave]

Odd -

I get

https://ttu-ir.tdl.org/bitstream/handle/2346/15557/31295015251746.pdf?sequence=1

https://www.researchgate.net/publication/229145886_In-process_dimensional_inspection_sensors

https://www.mdpi.com/2071-1050/14/12/7472/htm

http://kth.diva-portal.org/smash/get/diva2:660817/FULLTEXT09.pdf

(page 305 of the pdf.) <- most helpful.

https://www.academia.edu/5653579

but I used the entire term

manufacturing tolerance analysis "technological dimension"

 

[Burunduk]

supergee,
If it's in ISO documentation, maybe it has an English version with the words you are looking for? There should be if it is part of an international standard. If it has an English term used in ISO it may be easier to find out what is the equivalent ASME term.

And, is the practice you describe only intended for inspection of workpieces "in process" or can it be considered an alternative to inspect the finished part more conveniently (of course with some calculated risk + tighter tolerances as you indicated)?

 

[3DDave]

Here's an English version (from French researchers) on the topic:

https://www.researchgate.net/profil...mensions-in-an-interactive-design-context.pdf

The following are "dimension" types in that paper:

functional dimension
condition-dimension (this is also in the French language paper in the original question)
manufacturing dimension
mechanism–dimension
part dimension
Wade dimension
tool or adjustment dimension

Since the basis of the above is the work of Wade, a search for related literature show that Wade simply evaluated process plans to see if they would result in parts that complied with the requirements of their respective engineering drawing. In short checking to see if process steps in in-process dimensions would create an acceptable part.

For the most part the process is seen as a tolerance allocation problem not a dimension transfer problem. The difference is that the goal is to control tolerances - variation from nominal dimensions which is a higher order process than calculating the alternative dimension values for an alternate dimension scheme.

For example:

ABSTRACT
Process planning is an activity within the production process that translates design
requirements into a detailed description of instructions for transforming a raw stock of
material into a completed product. Instructions contain a sequence of operations that
should be followed in order to arrive at a final product that satisfies design requirements.

from

https://soar.wichita.edu/bitstream/handle/10057/794/d05023.pdf?sequence=3&isAllowed=y

, "OPERATIONAL TOLERANCE ALLOCATION AND MACHINE ASSIGNMENT UNDER PROCESS CAPABILITY AND PRODUCT VALUE CONSTRAINTS" by Safwan A. Altarazi

Also, helpfully:

resultant dimensions