Flex Plugs - Gage R&R (GR&R) - Threaded plugs used to check location of tapped holes

[Grizz1345]

I am looking for information on how to do GR&R on Flex Plugs. These are threaded plugs that we use to check the location of tapped holes using a CMM. I am interested in the X and Y dimensions. Any info would be appreciated.

 

[noboxwine]

I'll get it started

I am looking for information on how to do GR&R on Flex Plugs. These are threaded plugs that we use to check the location of tapped holes using a CMM. I am interested in the X and Y dimensions. Any info would be appreciated.

Humm.... I have used a CMM for years in automotive and never done such a thing. But, nothing says you cant, especially if you see a benefit. I am assuming you are wanting to use the flex plugs, on different parts that contain the tapped holes to do the R & R. If that is the case then just pick a set of both X & Y dimensions on a part, measure 10 of those parts, 3 times, with 3 different operators--just pull the plugs after each part is measured and put them in the next one. Plug your data into a Gauge R & R program and look at the results. There is nothing different about this CMM measurement technique where an R & R is concerned. If you are unfamiliar with R & R as a whole, we'd all be glad to help. Let us know and have a day !

 

[howste]

I agree with Noboxwine. Remember that you're analyzing the measurement system (meaning the flex plugs used with the CMM), not just the flex plugs themselves.

 

[Grizz1345]

Humm.... I have used a CMM for years in automotive and never done such a thing. But, nothing says you cant, especially if you see a benefit. I am assuming you are wanting to use the flex plugs, on different parts that contain the tapped holes to do the R & R. If that is the case then just pick a set of both X & Y dimensions on a part, measure 10 of those parts, 3 times, with 3 different operators--just pull the plugs after each part is measured and put them in the next one. Plug your data into a Gauge R & R program and look at the results. There is nothing different about this CMM measurement technique where an R & R is concerned. If you are unfamiliar with R & R as a whole, we'd all be glad to help. Let us know and have a day !

Thanks for your reply and input. The issue we are trying to address is the validity of the flex plugs. I believe that putting them in the same hole ten times will have a detrimental effect on the threads. We are talking aluminum heads versus harden steel flex plugs. We thought of making a hardened steel plate with the desired threaded holes in it. Production has been telling QC that the flex plugs are not accurate enough for inspecting these holes.

Have a great day.

 

[chalapathi]

Plug gages is an attribute inspection and you need to use the attribute MSA.
In the last message, you are talking about accuracy problem. Are you using standard ring gages for calibration of the Plug's.

 

[Jim Wynne]

Plug gages is an attribute inspection and you need to use the attribute MSA.
In the last message, you are talking about accuracy problem. Are you using standard ring gages for calibration of the Plug's.

I think the OP was referring to plugs used in checking the location of threaded holes, and not the threads themselves. The plugs allow location on the pitch diameter of the threads, which is the proper way to gauge location.

 

[Dave Dunn]

Thanks for your reply and input. The issue we are trying to address is the validity of the flex plugs. I believe that putting them in the same hole ten times will have a detrimental effect on the threads. We are talking aluminum heads versus harden steel flex plugs. We thought of making a hardened steel plate with the desired threaded holes in it. Production has been telling QC that the flex plugs are not accurate enough for inspecting these holes.

Have a great day.

Assuming these were purchased commercially and not manufactured in-house, they should hopefully have a certification listing the accuracy of the positional relationship between the thread pitch and the straight cylinder portion of each plug. You could always send them out for calibration if needed as well.

What sort of part tolerances are you working with regarding the tapped hole positions?

 

[Russ]

Re: Flex Plugs - Gage R&R (GR&R) - Threaded plugs used to check location of tapped ho

Does anyone have any directions for calibrating flex-plugs? We are having some differences here with those that like them and those that don't. I think they may be helpful but need a way to be sure they are not damaged other than what you can see. Any ideas?

 

[Stijloor]

Re: Flex Plugs - Gage R&R (GR&R) - Threaded plugs used to check location of tapped ho

Does anyone have any directions for calibrating flex-plugs? We are having some differences here with those that like them and those that don't. I think they may be helpful but need a way to be sure they are not damaged other than what you can see. Any ideas?

Hello Russ,

Have you talked to the manufacturer of the flex plugs?

Otherwise, look at this company's web page: "True Position Locators."

Disclaimer: I have no connection with this organization.

Stijloor.

 

[True Position]

Re: Flex Plugs - Gage R&R (GR&R) - Threaded plugs used to check location of tapped ho

Thanks for your reply and input. The issue we are trying to address is the validity of the flex plugs. I believe that putting them in the same hole ten times will have a detrimental effect on the threads. We are talking aluminum heads versus harden steel flex plugs. We thought of making a hardened steel plate with the desired threaded holes in it. Production has been telling QC that the flex plugs are not accurate enough for inspecting these holes.

Have a great day.

What method would production like done more accurate then flux plugs? Special made to pitch pin sized silicon nitride balls? (which honestly seems worse)

If you just want to make a point, show them repeatability of a few different methods and assuming the flex plugs are best you can show them data.

I'd recommend flex plugs, straight pins, probing a circle inside the tapped hole(worst method possible), helix WITH the pitch, helix across the pitch, and straight lines across the minor diameters.

The Zeiss forum guru on this topic spelled out his results when he did this testing(if my memory if accurate):
Best - Flex Plugs
Almost always fine - Helical With Pitch, Helical across pitch, Straight lines.

I've always used helical across the pitch and I've always repeated well enough with other CMM operators who've used flex plugs and straight pins for me to think it usually won't matter.