Interpretation problem

1. ## Interpretation problem

Please some one guide me how to interpret this drawing call off.. please check attached JPEG

Regards
Fss

2. ## Re: Interpretation problem

top face (A) must be flat within 0.5mm
..... same with opposite face but opp. face must also be parallel to A within 0.02mm.... and thickness must end up to be between 32.10/32.00mm
3.2mu surface finish is a little coarse but should be easily achieved

3. ## Re: Interpretation problem

4. Originally Posted by Superman
top face (A) must be flat within 0.5mm
..... same with opposite face but opp. face must also be parallel to A within 0.02mm.... and thickness must end up to be between 32.10/32.00mm
3.2mu surface finish is a little coarse but should be easily achieved
Thanks superman for reply..I am confused between 32+0.1mm and parallelism 0.02 with respect to datum A.and flatness..don't you think these callout conflict each other... need assistance....

5. Originally Posted by fsa
Thanks superman for reply..I am confused between 32+0.1mm and parallelism 0.02 with respect to datum A.and flatness..don't you think these callout conflict each other... need assistance....
It would seem that there is conflicting GD&T controls
.... but it basically needs both faces to be very parallel AND the 32.1/32.0 size maintained ( just to put it into easy language )
There is a lot more to what is implied in the dwg
... the 0.5 flatness allows a bit of wave form the machining of either face, or even a little bit of slope
... the 0.02 parallelism controls the wave/slope to be in-sync to each other
... the controlled thickness - obviously to fit a defined gap ( measured across faces using a micrometer )

(how's that for a breakdown explanation)

6. ## Re: Interpretation problem

sir you are right..but my concern is flatness 0.5mm on both faces and parallelism 0.02 with respect to Datum A..they both are conflicting each other ..if i maintain flatness 0.1mm on one face and 0.2mm on other face,,then the parallelism 0.02mm is automatically out of range..am i right ???

7. The datum face for the parallelism is the opposite face of the part. Therefore the smaller parallel tolerance could be maintained if the part faces were out-of-flat in the same direction. Sort of as if the part was a bent sheet.

8. ## Re: Interpretation problem

I do agree that the opp. face flatness is a redundant control as the parallelism & size is dictated by the A datum face machining

..... a sheet was a good example of the tolerance usage... the waviness cannot exceed 0.5mm over the face extents

9. ## Re: Interpretation problem

Originally Posted by Superman
I do agree that the opp. face flatness is a redundant control as the parallelism & size is dictated by the A datum face machining

..... a sheet was a good example of the tolerance usage... the waviness cannot exceed 0.5mm over the face extents
still some questions please check jpeg for details

10. Originally Posted by fsa
still some questions please check jpeg for details
IMO... flatness (when measured in free state) is less than 0.5mm TIR by dial... pass (or a feeler gauge check underneath)
... parallelism of one side to another... equal to or less than 0.02mm... pass (on maximum)
... thickness... size within tolerance... pass (on minimum)

You've done well for a 300x200 piece... hope you only need to do one.
( looks a real pr!ck of a job )

11. ## Re: Interpretation problem

oh really superman you mean my measuring method is right ..also just for confirmation that on different points when i measure from micrometer is actually measure parallelism...am i right???...i have to make 3000 parts a months..this is aluminium casting parts ..i have to machine just 2 faces as as per drawing.. also experience the material deformation or twisting after machining ...which is the cause of more then 0.09mm value if i check my part under dail tip ..my dail setup is fixed and i move the part along part profile ....

regards

fsa

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