JNieman
Aerospace
- Mar 26, 2014
- 1,128
I tried to search and find previous topics, but nothing that answered my issue came up. If you know of a thread, I'd be happy to know of it.
Goal: to be able to send machine programs to the machinists/machines that allow for coordinate variations to accommodate expected thermal expansion of the part. I have a proposed solution I would like feedback or alternate ideas to, if you please.
Problem:
1- Our inspection is to hold the room to 68 +/_ 1 degrees F. Our shop, while air conditioned and heated, may still fluctuate up to 20 degrees depending on environmental factors, if shipping has to have the roll-up doors open for extensive periods of time, etc.
2- Parts over 12" in length with tight tolerances for locations of features can often be hard to fight into tolerance when temperature differences get excessive.
3- With literally-written feature coordinate values, it does not allow for a machinist to /move/ holes or other features in any vector to accommodate expected fluctuations.
My Proposal: I have suggested to our programming department and to our Ops manager that during engineering review prior to production, I supply a "0.000x in per 10d F expected difference" or some such verbiage, and programming would insert a machine-variable rather than a coordinate value for such variables. I'm really only talking about hole locations with positional tolerances of .003 or less. On some parts, .003 (so, .0015 in any planar vector from nominal) can get shot to hell by .004 thermal expansion over 30" relative distance. I have programmed and set up HAAS machines where I was able to create semi-parametric programs based upon variable definitions. We do not have HAAS machines or controllers here, but rather the affected machines would be Okuma and Hurco VMCs. Hurco is it's own animal, but not a problem.
To me, this should be something that is always accounted for under normal circumstances as precision machinists, however this is my first job where our machinists are fed programs 100% and do not do any programming or modifying 'at the machine' so I must shift my normal expectations.
I would love to hear how others have solved this issue in your specific contexts. Thank you!
_________________________________________
NX8.0, Solidworks 2014, AutoCAD LT, Autocad Plant 3D 2013, Enovia DMUv5
Goal: to be able to send machine programs to the machinists/machines that allow for coordinate variations to accommodate expected thermal expansion of the part. I have a proposed solution I would like feedback or alternate ideas to, if you please.
Problem:
1- Our inspection is to hold the room to 68 +/_ 1 degrees F. Our shop, while air conditioned and heated, may still fluctuate up to 20 degrees depending on environmental factors, if shipping has to have the roll-up doors open for extensive periods of time, etc.
2- Parts over 12" in length with tight tolerances for locations of features can often be hard to fight into tolerance when temperature differences get excessive.
3- With literally-written feature coordinate values, it does not allow for a machinist to /move/ holes or other features in any vector to accommodate expected fluctuations.
My Proposal: I have suggested to our programming department and to our Ops manager that during engineering review prior to production, I supply a "0.000x in per 10d F expected difference" or some such verbiage, and programming would insert a machine-variable rather than a coordinate value for such variables. I'm really only talking about hole locations with positional tolerances of .003 or less. On some parts, .003 (so, .0015 in any planar vector from nominal) can get shot to hell by .004 thermal expansion over 30" relative distance. I have programmed and set up HAAS machines where I was able to create semi-parametric programs based upon variable definitions. We do not have HAAS machines or controllers here, but rather the affected machines would be Okuma and Hurco VMCs. Hurco is it's own animal, but not a problem.
To me, this should be something that is always accounted for under normal circumstances as precision machinists, however this is my first job where our machinists are fed programs 100% and do not do any programming or modifying 'at the machine' so I must shift my normal expectations.
I would love to hear how others have solved this issue in your specific contexts. Thank you!
_________________________________________
NX8.0, Solidworks 2014, AutoCAD LT, Autocad Plant 3D 2013, Enovia DMUv5