Different types of thread gages, how many uses before calibration?
Close
Login to Your Account
Page 1 of 2 12 LastLast
Results 1 to 20 of 29
  1. #1
    Join Date
    Feb 2015
    Country
    CANADA
    State/Province
    Alberta
    Posts
    82
    Post Thanks / Like
    Likes (Given)
    65
    Likes (Received)
    8

    Default Different types of thread gages, how many uses before calibration?

    I've been asked to develop a system to track thread gauge usage so when our yearly calibration interval for thread gages is up we can compare to the amount of uses and determine if an extension is required or if we should send the gage for calibration. I was just wondering for Standard UN threads , NPT threads and both API 7-2 and 5B threads what a approperiate amount of uses before calibration would be. I do realize that realistically the number of passes has something to do with it (the smaller the diameter the more times the gage goes around ) but i was hoping to just to establish a guide line for each of these catigories. So i guess the question is what are some of your shops standard guidlines for gage recalibration intervals, either time or amount of uses?

  2. #2
    Join Date
    Nov 2005
    Location
    Maryland
    Posts
    8,201
    Post Thanks / Like
    Likes (Given)
    746
    Likes (Received)
    1103

    Default

    I've never encountered a calibration system that allowed the user to "extend" the certification's period of validity.

    Every cal sticker bears an expiration date. After that date it is no longer valid.

    Changing that date in any way voids the sticker.

    Thread gages are very robust items. They should last for a long time as long as you don't torque them with a pipe wrench.

    Your cal lab will determine if a gage has worn to the point that it can no longer be certified.

    - Leigh

  3. Likes drgnrider, TeachMePlease liked this post
  4. #3
    Join Date
    Jul 2012
    Country
    UNITED STATES
    State/Province
    Kansas
    Posts
    110
    Post Thanks / Like
    Likes (Given)
    86
    Likes (Received)
    43

    Default

    Quote Originally Posted by Quality Josh View Post
    ... I do realize that realistically the number of passes has something to do with it (the smaller the diameter the more times the gage goes around ) but i was hoping to just to establish a guide line for each of these catigories. ...
    Other factors that will also affect the gage, are:
    - material used in (steel, cast, stainless, etc.)
    - user (light touch, pulls to side when used, etc.)
    - condition of hole (clean, off-center, dry/amount of lubrication, etc.)
    - tool used to make the hole (sharp, worn, off-center, etc.)
    so saying X-amount of holes or times into holes is very hard to guess.

    Agree with Leigh: cal sticker date is absolute. Now, you can use the data (history) from the cal lab to extend/reduce the time the calibration is valid.

    my two-cents...

    drgnrider
    Calibration & ISO Coordinators

  5. Likes Eric M, yanshi liked this post
  6. #4
    Join Date
    Dec 2009
    Location
    Louisiana
    Posts
    425
    Post Thanks / Like
    Likes (Given)
    141
    Likes (Received)
    240

    Default

    The only way I think you could get away with this is if your gages were to come back from calibration dipped in protective wax/plastic (that would prevent use unless removed) and your one year interval began from the first use of the gage after calibration instead of the calendar date of calibration. The argument for this is that when you purchase any gage with a certificate of calibration that calibration is performed directly after manufacture not immediately prior to shipping. So a well packaged and protected, calibrated/verified gage sitting on your shelf is no diffrent than a well packaged and protected, calibrated/verified gage sitting on someone else's shelf. There are many here (myself included) however that never trust a factory calibration cert and have their new gages calibrated/verified by a local, trusted lab before their first use. It all comes down to what you customers and auditors feel is appropriate, I wouldn't do it.

  7. Likes Eric M, Paolo_MD liked this post
  8. #5
    Join Date
    Nov 2005
    Location
    Maryland
    Posts
    8,201
    Post Thanks / Like
    Likes (Given)
    746
    Likes (Received)
    1103

    Default

    Quote Originally Posted by drgnrider View Post
    you can use the data (history) from the cal lab to extend/reduce the time the calibration is valid.
    Certainly the cal lab can recommend a change in the calibration interval if they see historic data to support such a change.

    However, understand that some customers have their own requirements, as in all vendors having a 12-month calibration cycle.
    This is a cost-effective specification for the customer, since it reduces their incoming inspection requirements.

    Maintaining verifiable and traceable accuracy certification that's acceptable to all customers is not as simple as it would seem.

    - Leigh

  9. #6
    Join Date
    Nov 2014
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    35
    Post Thanks / Like
    Likes (Given)
    24
    Likes (Received)
    2

    Default

    Quote Originally Posted by The real Leigh View Post
    Certainly the cal lab can recommend a change in the calibration interval if they see historic data to support such a change.

    However, understand that some customers have their own requirements, as in all vendors having a 12-month calibration cycle.
    This is a cost-effective specification for the customer, since it reduces their incoming inspection requirements.

    Maintaining verifiable and traceable accuracy certification that's acceptable to all customers is not as simple as it would seem.

    - Leigh
    Like you said unless specified by a customer a calibration cycle can (depending on what you are conforming to, I am following TS-16949) be as long or short as you want I have certain fixtures I run R&R's on every 6 months and others that are every 3 years it all depends on what the Calibration Tech feels necessary.

  10. #7
    Join Date
    Nov 2005
    Location
    Maryland
    Posts
    8,201
    Post Thanks / Like
    Likes (Given)
    746
    Likes (Received)
    1103

    Default

    Yep. There are no laws mandating any particular cal interval.

    The choice depends on many factors.

    12 months seems to be a pretty universal interval in most business sectors, not just mechanical measurements.

    That's probably too long for any gauge in a production environment measuring every part as it comes off the machine.

    - Leigh

  11. Likes TWiltonIV, Quality Josh, Paolo_MD liked this post
  12. #8
    Join Date
    Feb 2015
    Country
    CANADA
    State/Province
    Alberta
    Posts
    82
    Post Thanks / Like
    Likes (Given)
    65
    Likes (Received)
    8

    Default

    So what you are saying no matter if the gauge has been used 3 time over the course of the year it should still be sent for calibration? that could get really expensive...

    On the flip side what if a gauge is used enough over the course of 3 months to warrent a calibration? I've been told to tally the uses at the end of each month as well as when the 1 year calibration is up and then we can determine if it need a calibration. Does it not make any sence to do this and stick with all the calibrations be at 1 year and that is that?

    Basicly I would keep track of the one year to have a look at the gauge, determine if there is damage and write the extension form that we have developed and replace the sticker if we dont send it or send it if need be and then at the end of every month do a tally to determine use and send it if need be or not (no new sticker required because they are all 1 year according to company policy)... i guess i am just asking if this procedure could be used or if it is ass backward

  13. #9
    Join Date
    Nov 2005
    Location
    Maryland
    Posts
    8,201
    Post Thanks / Like
    Likes (Given)
    746
    Likes (Received)
    1103

    Default

    Quote Originally Posted by Quality Josh View Post
    Basicly I would keep track of the one year to have a look at the gauge, determine if there is damage and write the extension form that we have developed and replace the sticker
    YOU cannot make any changes to the calibration sticker on any instrument unless you are a certified and traceable calibration laboratory.
    There is no such thing as an "extension form" that's acceptable in the industry.

    YOU cannot certify anything to anything other than house standards. That's circular and unacceptable in the business world.

    Many large companies do maintain their own traceable cal labs. Think GM, Ford, Boeing, etc.

    You think getting your tools calibrated is expensive... wait til you budget setting up, maintaining, and certifying a traceable cal lab.

    - Leigh

  14. Likes TeachMePlease liked this post
  15. #10
    Join Date
    Feb 2014
    Location
    Sunny South West Florida, USA
    Posts
    2,497
    Post Thanks / Like
    Likes (Given)
    10017
    Likes (Received)
    2937

    Default

    Depends on what kind of certification your customers expect.

    Do you make stuff from cocktail napkin drawings, and the tolerances are "Make it work"?

    Or are you making aerospace parts with tolerances of .0005 or less, and thread callouts like 3/4-16 UNF 3A?

    Minimum should be once a year. Period. What's more expensive, sending a gage out for calibration, or getting a whole batch of parts back because the threads are f*cked?

    Certainly assess the wear, use this to determine the maximum life for your most used gages. These might need certification every 3-6 months, or even less, depending on how you use them.

    But "Well, average wear for this gage is xx/year, so we only calibrate it every 3 years" is a really stupid system, IMHO.

    If you get into any sort of ISO certification, it won't even be a question, you WILL be calibrating gages yearly.

  16. Likes The real Leigh, Eric M, Paolo_MD liked this post
  17. #11
    Join Date
    Jun 2006
    Location
    Hawthorne, CA USA
    Posts
    195
    Post Thanks / Like
    Likes (Given)
    41
    Likes (Received)
    66

    Default

    We use a 1000 pass calibration cycle. Each thread gauge has a 3x5 card with 1,000 check boxes.
    Each time the gauge is put in a hole a box is checked, when the card is full it is sent to calibration.

    This method has been examined and accepted by different AS9102 auditors.
    From past experience a 10-32 plug gauge is good for about 3,000 times down the hole in our shop.

    The main reason for this method is to avoid the unnecessary cost of annual inspection of a extensive gauge library, most of which are rarely used.

    On a similar note all our surface plates, CMM's, gauge blocks, etc. calibrated by a outside lab are not allowed to put a expiration date on their calibration label,
    only date of calibration. It is our written procedures for each item based on historical data that state the calibration duration.

  18. Likes TeachMePlease, Quality Josh, Paolo_MD liked this post
  19. #12
    Join Date
    Feb 2014
    Location
    Sunny South West Florida, USA
    Posts
    2,497
    Post Thanks / Like
    Likes (Given)
    10017
    Likes (Received)
    2937

    Default

    Funny, every item we have that gets a calibration is required to have a "Last calibrated" date and a "Calibration due" date.

  20. #13
    Join Date
    Feb 2015
    Country
    CANADA
    State/Province
    Alberta
    Posts
    82
    Post Thanks / Like
    Likes (Given)
    65
    Likes (Received)
    8

    Default

    It funny cause 1 of the 2 engineers that is asking me to use this process use to be an iso auditor...

  21. #14
    Join Date
    Feb 2015
    Country
    CANADA
    State/Province
    Alberta
    Posts
    82
    Post Thanks / Like
    Likes (Given)
    65
    Likes (Received)
    8

    Default

    Quote Originally Posted by TeachMePlease View Post
    Funny, every item we have that gets a calibration is required to have a "Last calibrated" date and a "Calibration due" date.
    Yeah all the sticker we deal with do as well but the way this guy is looking at it is if the gauge has not been used then why send it, write a new sticker and with his "extension form" and and wait till there is is enough uses for a calibration. I am not saying this is correct thou its just what i am being asked to do.

    Quote Originally Posted by The real Leigh View Post
    Yep. There are no laws mandating any particular cal interval.- Leigh
    So leigh if this is the case could we specify to the choosen cal lab the interval we wanted? I know for a fact in the API Spec's that we deal with they leave calibration really open ended as far as an interval goes, specifically spec 5B and 7-2. How a bout standard UN thread gages and NPT? is it open ended as well?

  22. #15
    Join Date
    Feb 2015
    Country
    CANADA
    State/Province
    Alberta
    Posts
    82
    Post Thanks / Like
    Likes (Given)
    65
    Likes (Received)
    8

    Default

    I know im getting a bit off topic here but I also always was taught that ISO 9001 cerification was more of a guidline on how to plan your process and follow them (ie. Process maps). I didnt think that it dictated calibration intervals, that it just said that when you do decide on an interval you have to follow it? Is this not the case TeachMePlease?

  23. Likes Eric M liked this post
  24. #16
    Join Date
    Mar 2011
    Location
    Huron
    Posts
    1,351
    Post Thanks / Like
    Likes (Given)
    1881
    Likes (Received)
    845

    Default

    I think this is something you need to discuss at length with your calibration lab. As far as I know, the certification guarantees the tool is good right now, and nothing else. It is up to your discretion as to when and if the tool needs recalibration sooner. The one year recheck is simply a convention of the commonly accepted calibration system used around the world.

  25. Likes drgnrider, Paolo_MD liked this post
  26. #17
    Join Date
    Jul 2012
    Country
    UNITED STATES
    State/Province
    Kansas
    Posts
    110
    Post Thanks / Like
    Likes (Given)
    86
    Likes (Received)
    43

    Default

    I have many different gages with calibration ranging from 6-mo to 5-yrs, (and my ISO-9001 CB auditors have never written a "non-conformance" nor "observation"). These intervals are based on historical use and calibrations. Many of my 3-yr gages, (max interval for production gages), still have the wax from the last calibration when they get sent off... why, because the interval says 3-yr. We do not have any 'if not used, extend' allowances. My set plugs are on a 5-yr plan as they are used at most twice a year, depending on ring gage usage, and then only by me.

    I send gages to our outside cal lab and specify interval for each gage. They don't complain, just note in my records "customer specifications". The same is true for our gages that we have modified from "industry standard" on tolerances; the cal lab makes note of the deviation and they calibrate to that. Our QA Manager has to buy-off on all deviations from manufacturer/industry standards, and then, after a risk assessment and agreement with the appropriate production manager(s) and Factory Director (we have a 3.5"-6-UN plug gage that they allow +.0030", since part tolerance is +.0052", although industry standard says +.0004"). Any change I want to make to intervals, needs to be approved by the QA manager after presenting my justification/Risk-assessment to him.

    From an ISO view - ISO does not care too much about what the procedures say as long as that is what you do. If it says to soak your gages in the calibration room 48-hours before calibrating, then they had better soak for 48-hours. Customer and the industry might frown upon your "extension", but ISO doesn't as long as it is part of your written procedure and you can justify your reasoning and the Risk to your product (as an auditor, I will ask for this).

  27. #18
    Join Date
    Jul 2012
    Country
    UNITED STATES
    State/Province
    Kansas
    Posts
    110
    Post Thanks / Like
    Likes (Given)
    86
    Likes (Received)
    43

    Default

    Quote Originally Posted by Winterfalke View Post
    I think this is something you need to discuss at length with your calibration lab. As far as I know, the certification guarantees the tool is good right now, and nothing else. It is up to your discretion as to when and if the tool needs recalibration sooner. The one year recheck is simply a convention of the commonly accepted calibration system used around the world.
    Agree. The cal lab's certificate is only validating the gage, and ergo the product you have already checked with it, is good. Reason it is better to calibrate gages vs. just buying new ones.

  28. #19
    Join Date
    Nov 2005
    Location
    Maryland
    Posts
    8,201
    Post Thanks / Like
    Likes (Given)
    746
    Likes (Received)
    1103

    Default

    Quote Originally Posted by in2glamisgirl View Post
    We use a 1000 pass calibration cycle. Each thread gauge has a 3x5 card with 1,000 check boxes.
    Each time the gauge is put in a hole a box is checked, when the card is full it is sent to calibration.

    This method has been examined and accepted by different AS9102 auditors.
    From past experience a 10-32 plug gauge is good for about 3,000 times down the hole in our shop.

    The main reason for this method is to avoid the unnecessary cost of annual inspection of a extensive gauge library, most of which are rarely used.
    That's fine, but you cannot claim the gage to be certified beyond the expiration date on the cal label.

    Quote Originally Posted by in2glamisgirl View Post
    On a similar note all our surface plates, CMM's, gauge blocks, etc. calibrated by a outside lab are not allowed to put a expiration date on their calibration label, only date of calibration.
    I'm amazed you could find a cal lab that would agree to send out items with a blank expiration date.

    I expect they could lose their certification for doing so.

    - Leigh

  29. #20
    Join Date
    Nov 2005
    Location
    Maryland
    Posts
    8,201
    Post Thanks / Like
    Likes (Given)
    746
    Likes (Received)
    1103

    Default

    Quote Originally Posted by Quality Josh View Post
    So Leigh if this is the case could we specify to the chosen cal lab the interval we wanted?
    Yes, I believe you could do that.

    Some labs might question you on it, like wanting to see an in-house standard that supports your request.

    - Leigh

  30. Likes Quality Josh, Paolo_MD liked this post

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •