huangyhg

asme y14.5 for inspection?
hi all,
is there a standard for inspection of parts made to drawings produced using asme y14.5?
example. i produce the drawing but is my inspector working to a standard for checking the parts?
thanks,
---solidworks 2008 sp3.0---
eng-tips forums is member supported.
barm,
i think the answer is no. supposedly the y14.5 is a set of tools to apply geometric theory to the parts. it is left to the inspector as to how he goes about verifying that geometry.
in otherwords, he might use an open setup, special gages or a cmm for verification. whatever he might have available should be able to perform the task, that is with some effort on his part.
all that being said, if you know how the parts will be inspected, you can somewhat tailor the drawing to be a little more 'user friendly'.
fwiw

no there isn't and that is a great problem with the standard.
y14.5m - 94 does not really get into the application of gd&t and also does not get into the confirmation methods either. that is one of the reasons one might see a drawing that is completely covered with gd&t including having default symbols such as profile of a surface in notes. it doesn't help anyone. gd&t should be used if there is a function and relationship between the features or its mating parts. otherwise, it should not be used.
thanks for your input.
it's been my experience that inspection methods of products are born out of relationships/conversations and agreements between the producer and the customer. but what if there is none or the customer is not able to provide direction?
is this statement "gd&t should be used if there is a function and relationship between the features or its mating parts. otherwise, it should not be used." from the y14.5m standard?
i've designed checking fixtures and attribute gauges. this is a whole new ballgame and in my opinion has some big weakness'. now having just said that, i do know there exists a asme standard but i haven't seen it or even heard of it's use in this industry of checking fixtures.

---solidworks 2008 sp3.0---
inspection needs to inspect per the standards stated on the dwg.
chris
solidworks/pdmworks 08 3.1
autocad 06/08
chris:
usually the drawings states "complies with asme y14.5m-94" but i have never seen standards for inspection on the drawing -ever!
barm:
i learned gd&t so many years ago using a book by lowell foster and i always re
asme y14.5m-94 is the standard for inspection to follow.
chris
solidworks/pdmworks 08 3.1
autocad 06/08
most of the figures you see in the standard that have "means this" in the upper left corner are an illustration for inspection. it doesn't say "use cmm" or "starrett calipers only" but it tells you the theoretical condition that the limits of size and condition must not exceed. the way you get there is up to the inspector. chris said it twice and i concur, you use specified standard to determine the inspection method. if you're asking if there is a standard that says how to inspect to y14.5m-1994 then i concur with dave...no.
the problem that you can run into using coordinate dimensioning (non-gd&t) is that there is ambiguity in inspection. gd&t will eliminate this. an example would be a square plate with a series of holes called out 1" from one edge. is the intent that the holes be 1" from the edge or are they really supposed to be aligned perpendicular to the bottom edge. if the part is out of square, should the holes follow the edge or should they be perpendicular to the bottom edge? while an inspector would probably make sure the holes are 1" from the edge, there is still a chance that the part wouldn't actually work because the designer may have needed the perp requirement but didn't think about the fact that the od of the part could actually be out of square by as much as the default angular tolerance per the implied 90 rule.

powerhound, gdtp t-0419
production supervisor
inventor 2008
mastercam x2
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ssg, u.s. army
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as far as i am aware there is no standard on how you measure anything. for example take something as simple as a hole size, a go/no gauge will do this but it gives no indication of what is happening purely if it is in or out of limit. the inspector may wish to actually measure parts to use spc, in nearly all cases holes get smaller as the cutting or forming tool wears and by doing this you can get (or very close too) zero rejects by replacing tooling as it becomes worn or blunt. as far as i am aware no standard tells you which route you have to go down.
as for fixture design this will depend greatly on what you are measuring, but this site gives a good general idea of some principles.
i would hope this might have some relevance. i can think of gd and t as a roadmap. the inspection is the means of getting to the intended target, (feature). you have several methods of getting there; land, sea, or air. even then you have different vehicles to utlilize.
powerhound:
i agree that your example with 4 holes can be closely controlled using positional tolerances rather than co-ordinate tolerances as long as there is a function and relationship of the holes to the mating part or within the part. if the holes are to lighten the product or have no relationship, then co-ordinate tolerancing, in my opinion, is adequate.
chris:
yes the standard does reflect dotted lines showing what the symbols means but not how to measure it. on flatness, as an example, should we use a cmm and 24 points, 12 points or scan the surface. we could also use a granite table, height gauge with dial indicator and 3 point set up. we would then sweep the surface. the standard does not help here.
a great example is concentricity. the standard would shows dotted lines around the datum center line but most people cannot figure this out. they usually perform a positional tolerance inspection rather than finding the median points of diametrically opposing elements.
dave d.

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