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tp20 madness!

i had a program giving bad data (.005 oot) for a length characteristic on a production floor cmm.  this was verified in the gage lab with an open setup.

i ran the program on the gage lab cmm and got good data (matched the open setup).

i swapped out the tp20 and tip on the production floor cmm, reran the same program and part, and got good data (matched the open setup and gage lab cmm).

i then ran the same program with the same part on the gage lab machine with the "bad" tp20 and tip and got good data.

its a 3x30 tip in 0,0 orientation.  no other orientations seem to be offering contrary data.

thoughts?

Parents
  • Make sure you clean the probe interfaces with the yellow renishaw CK200 goo. 
    Since magnets hold the tp20 module on, any little shard of debris (specifically metal shavings) will promote egregious & random erroneous data. 

    TP20's also have the shortest lifespan of all the renishaw product (25,000 changes per the manual, and unofficially, ~2 million hits).
    TP200's for example are spec'd to last >10 million hits.

    Swapping modules (with new to compare) is the formal method of affirming end of life for a tp20 module.

  • How often should we be cleaning them? We occasionally get overspeed errors in different Axes (once every 1-2 months), and probe unseated even at low speeds, but very rare. Not sure how old this TP20 module is we have.

  • -Overpseed is the CMM's drivetrain not keeping up with what it was commanded to do.  Not related to the probe sensor whatsoever.
    -Probe unseated is the result of potentially a dying probe sensor or noise in your drivetrain (probe vibrates when moving and triggers a hit).  You can (at increased risk of crashing with catastrophic results) get Hexagon to switch off probe sensor trigger detection while it's traversing. 

    From Renishaw: 

    Renishaw recommends that all kinematic coupling mechanisms incorporated in probing devices are cleaned before first use, and thereafter at regular intervals.

    Each kinematic cleaning kit comprises of strips of 'yellow tack' material which should be used to clean the precision ball seatings and permanent magnets found on the probe and probe heads. Sensors requiring cleaning include: REVO®, PH20, RSP2, RSP3, SFP, SP25M, SP25 modules, TP20 modules and TP200 modules.

    --We clean and calibrate our TP200's once a month, but we are in a non-production environment, and haven't discovered any contamination issues at this frequency.  your environment might justify more or less frequent cleaning.

  • This is a new Global S from July 2022, how likely  is it that we experiencing drivetrain issues already? These occur very very infrequently and seem to be random, like months to weeks apart and can't really be reproduced. This happens at low speeds more often than higher speeds like during Find Center. I am not sure of how rare/frequent drivetrain issues occur in CMMs.

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  • This is a new Global S from July 2022, how likely  is it that we experiencing drivetrain issues already? These occur very very infrequently and seem to be random, like months to weeks apart and can't really be reproduced. This happens at low speeds more often than higher speeds like during Find Center. I am not sure of how rare/frequent drivetrain issues occur in CMMs.

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