Gage Pin Gauge R&R - Our calibration guy said he doesn't know how to do one

Gage Pin R&R - Our calibration guy said he doesn't know how to do one

Please Help. The MSA doesn't explain how to do a pin gage R&R and we are being required by one of our customers (Yazaki) to provide this study.
Of course we do R&R's on other gages but our calibration guy said he didin't know how to do one on the pin gages.

I appreciate your help.
LMM

If you have access to the AIAG MSA manual. . .there are Attribute Gage study guides there.

Why they so stuffy on the R&R. . . narrow-limit your specs and gage away.

I agree with Taz on the "narrow limit" however there are times when that's not possible/feasible (tolerance of +/-.001" - which would lead me to ask why you would be using a pin gage in the first place). We tend to go the "easier" route - taking 20 parts and two operators - each measuring the 20 parts twice. If all 4 meaurements "agree" (OK or NOT OK), the Gage R&R is acceptable. One key is to have at least one part at each end of the tolerance and, at least, a couple of parts out of tolerance (it's just as, if not more, important to be able to identify "bad" parts as it is "good" ones). I've attached a form we use (from the MSA manual).



Hope that helps,

Bill

100% agreement Bill. . .

I remember a case when 2 Q-Techs called from a customer and told me that they had measured the hole diameter (.062") in a $0.02 rivet with their brand new $250,000 CMM and said that the diameter was small. . .

I politely excused myself and went to the gage pin case and got out a .062" dia. pin and checked the part. . . it was OK. . . pin fell in. .

The guys wouldn't buy my story. . .they got their boss on the phone. . . the guys went on about the new $250,000 CMM and their fixturing and such while the boss listened. . . I then simply told the boss that I just took my $1.75, .062" diameter gage pin and put it into the hole easily. . . she thanked me, and told the boys she wanted to see them in her office. . .

Point here, don't overkill the thing. . . simple is better. . .

Taz & Bill - on the question of using pin gages:

I've had customers require CMM print outs for all dimensions except holes and slots, where they specified pins. The problem is that the CMM gives you a "best fit". If you take three hits on the circle, the CMM calculates size, roundness and location off of those three hits. The more hits you take, the better the CMM's "picture" of the hole. Burrs and out of round conditions are best found with pins.

Cari Spears said:

Taz & Bill - on the question of using pin gages:

I've had customers require CMM print outs for all dimensions except holes and slots, where they specified pins. The problem is that the CMM gives you a "best fit". If you take three hits on the circle, the CMM calculates size, roundness and location off of those three hits. The more hits you take, the better the CMM's "picture" of the hole. Burrs and out of round conditions are best found with pins.

Click to expand...

The issue with a CMM measuring a hole size (at least in my experience) is that it will give you an average diameter - not a "functional" diameter. Probe size is very important but it can still distort the "functional" size by hitting in a low spot, for instance. We just purchased a new CMM form Zeiss and, supposedly, the new software can give functional size, runout, concentricity, etc. - I'm skeptical (but trying to be open-minded ). Once again, in my experience, the only way you will know if a hole is functional (regarding size) for whatever is to go into/through it, is with a pin gage.

I do question using a pin gage to check "out of roundness".

Bill

Cari Spears said:

Taz & Bill - on the question of using pin gages:

I've had customers require CMM print outs for all dimensions except holes and slots, where they specified pins. The problem is that the CMM gives you a "best fit". If you take three hits on the circle, the CMM calculates size, roundness and location off of those three hits. The more hits you take, the better the CMM's "picture" of the hole. Burrs and out of round conditions are best found with pins.

Click to expand...

The CMM is a great tool. . .but it, as all other tools, has it's strengths, weaknesses and limitations.

The Pin gage, has it's strengths and weaknesses also. . . try to measure too many burred-up holes, and you develop it into a straight reamer. . .

I have to disagree with you on one point though. . . Out-of-roundness is also a limitation. . . how do you measure the max condition of the hole with the pin gage?? I completely agree with using a pin gage for a "functional" fit. . . it is afterall a functional attribute gage.

and a heck of a lot less expensive that a CMM. . .

The Taz! said:

. . . try to measure too many burred-up holes, and you develop it into a straight reamer. . .

Click to expand...

Or your operators use them with (or as) a hammer from the get go

Bill

Splined Reamer

Bill. . .

I have to recant this to you. . .

In a past life I sold and installed turn-key SPC data collection systems. . .

At a gun manufacturer here in CT, I was on the shop floor reviewing the operation, and I witnesses an operator holding a grenade launcher barrel in her hand. . .in the end of the barrel was a splined gage. . .about 2" in diameter (and VERY expensive) . . . she was pounding the opposite end of the gage on a granite surface plate to try and deburr the barrel. . . I almost dropped my teeth. . . and they are original equipment and attached! :mg:

I showed this "practice" to the QE I was working with, and he merely commented, "What ya gonna do."

Lmccrary said:

Please Help. The MSA doesn't explain how to do a pin gage R&R and we are being required by one of our customers (Yazaki) to provide this study.
Of course we do R&R's on other gages but our calibration guy said he didin't know how to do one on the pin gages.

I appreciate your help.
LMM

Click to expand...

A gage R&R for pin gages? If you have an accredited (to ISO/IEC 17025) calibration lab calibrate them and provide a cert with readings and measurement uncertainty, there is no valid reason to do a gage R&R for the pins....unless that is what you manufacture.

Hershal