GO NO-GO gage to check Profile

[bxbzq]

I don't know too much about inspection. To inspect a part as shown in attached, is it good practice to build and use GO NO-GO gages? The gages will have internal contour 0.4 offset from true profile. One larger and the other one smaller.

 

[pmarc]

GO gage can be built and used - this will verify whether the contour has or has not violated the outer boundary of profile tolerance zone.

However NO-GO gage (for verification of violation of the inner boundary of profile tolerance zone) is of no use here. Why? Imagine 2 scenarios:
1. Entire contour is not violating the inner boundary -- the part meets print requirements and will not fit into NO-GO gage;
2. Almost entire contour is not violating the inner boundary. Small portion of the part somewhere along the contour is falling "below" the inner bondary -- the part does not meet print requirements, yet will not fit into NO GO gage too.

Two different conditions of the part (one satisfying the print, second not) give you the same effect during inspection. This shall not happen.

 

[powerhound]

That is certainly one way to go. Using an optical comparator is another but what you propose will be fine.

John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[greenimi]

What about, using the GO gage designed and built (as pmarc suggested to check the outer boundary / profile) and then using 0.8mm gage pin in conjunction with the GO gage to check for the inner profile?
If the No-Go pin 0.8mm gage will go then the inner boundary has been violated.
The 0.8mm No-Go pin gage should not go between the part and the GO gage no matter what. If the 0.8mm pin goes, then there is no material where suppose to be material and then as I said before the inner profile is not in tolerance.

 

[pmarc]

greenimi,
As far as I imagine, the 0.8mm NO-GO pin would not be able to detect any actual errors "deeper" than 0.8 (in a direction normal to true profile) and "tighter" than 0.8 (in a direction along true profile). In such cases the NO-GO pin will not go, yet the part will not be satisfying profile requirement.

 

[greenimi]

pmarc,
You are right. I forgot about that. Thank you.
I wish to reach that day when I can successfully disagree about GD and T with pmarc

 

[CheckerHater]

Belive me, it's no fun